summaryrefslogtreecommitdiff
path: root/Master/texmf-dist/source/latex/tcldoc/dtxload.dtx
blob: f68a0ca3a8b9f64a416222d618dfe76d25c9e23a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
%
%
% \iffalse Meta-comment
%
%<*driver>
\documentclass{tcldoc}

\DeclareRobustCommand{\package}[1]{\textsf{#1}}
\newcommand{\Alpha}{\textit{Alpha}}
\newcommand{\AlphaTk}{\textit{Alphatk}}

\PageIndex
\setcounter{IndexColumns}{2}
\CodelineNumbered
\RecordChanges
\IndexPrologue{\section*{Index}\markboth{Index}{Index}%
   Numbers written in italic refer to the page where 
   the corresponding entry is described; numbers underlined refer 
   to the definition; numbers in roman refer to the pages where 
   the entry is used.}
\expandafter\def \expandafter\GlossaryParms \expandafter{\GlossaryParms
   \hbadness=10000\emergencystretch=2cm}

\begin{document}
\DocInput{dtxload.dtx}
\PrintChanges
\PrintIndex
\end{document}
%</driver>
% \fi
% 
% \title{\package{dtxload} --- loading \Tcllogo\ code directly from 
%    \texttt{.dtx} source files}
% \author{Lars Hellstr\"om^^A
%    \thanks{E-mail: \texttt{Lars.Hellstrom@math.umu.se}}}
% \date{December 20, 2000}
% \maketitle
% 
% \begin{abstract}
%   \package{dtxload} is a feature for the text editor \Alpha. It 
%   implements a command for loading a piece of \Tcllogo\ code directly 
%   from a \texttt{.dtx} file.
% \end{abstract}
% 
% \tableofcontents
% 
% \section{Usage}
% 
% \subsection{About \Alpha}
% 
% About \Alpha\ itself, the \Alpha~v\,7.3 manual says the following:
% \begin{quotation}
%   \Alpha\ is a very powerful, multi-purpose text editor.
%   \Alpha\ is multi-modal, which means it switches between different 
%   modes depending on which type of document you are editing. Everybody 
%   who has used Emacs knows about this concept. The idea with different 
%   modes is to change \Alpha's behaviour depending on which kind of text 
%   you're editing. For example if you're programming in C$^{++}$ or 
%   editing a \LaTeX\ document you want different features.
%   
%   \Alpha\ is very customizable. Much of \Alpha's functionality is 
%   implemented in `packages' or `extensions'. [\dots]
%   \Alpha\ uses Dr.~Ousterhout's \emph{Tool Command Language} (\Tcllogo) as 
%   an extension language. Many of the functions bound to keystrokes, 
%   as well as many of the functions in the menus, are written in \Tcllogo. 
%   All the `packages' or `extensions' just mentioned are all written 
%   in \Tcllogo. Anybody who wants can write new packages for \Alpha! 
%   
%   Of course, you don't have to learn \Tcllogo\ to use \Alpha. You can 
%   have lots of use of \Alpha\ without knowing anything about \Tcllogo. 
%   But if you want to become a real power user, you should consider 
%   trying it out. Then the possibilities of customizing \Alpha\ are 
%   unlimited.
% \end{quotation}
% Originally \Alpha\ only existed on the \mbox{MacOS} platform, but 
% recently the program was rewritten in Tk.\footnote{Tk is an extension of 
% \Tcllogo\ which includes GUI support.} In that form (which is called 
% \AlphaTk), \Alpha\ can be run on any platform for which there exists 
% a port of Tk!
% 
% \medskip
% 
% There are also some \Alpha-related URLs which should be mentioned. 
% \Alpha's official home page is~\cite{AlphaHome}, but it is currently 
% rather out-of-date. More recent information can be found on 
% e.g.~\cite{DocScriptingAlpha}, which also has links to many other 
% \Alpha-related sites. The home page for \AlphaTk\ is~\cite{Alphatk}.
% 
% 
% 
% \subsection{Installation}
% 
% To install \package{dtxload} as an \Alpha\ feature, you first \LaTeX\ 
% the file \texttt{dtxload.ins}---this will generate a file 
% \texttt{dtxload.tcl}, which contains the \Tcllogo\ code for the 
% package in a form that \Alpha\ understands. Then follow the normal 
% procedure for installing an \Alpha\ package, i.e., open 
% \texttt{dtxload.tcl}\footnote{Which should be somewhere outside 
% \Alpha's directory subtree.} in \Alpha---this will trigger the 
% automatic installation dialog for the package and you proceed as 
% usual.
% 
% 
% \subsection{Loading \Tcllogo\ code}
% \label{Ssec:Loading}
% 
% To load (evaluate) a piece of \Tcllogo\ code in a \texttt{.dtx} 
% document, simply select that code and press \marginpar{Loading code: 
% \textsf{Cmd--L}}Command--L. The commands are evaluated one by one and 
% the result of each command will be shown at the current log destination 
% (by default the status line, but that can be changed). In case one of 
% the commands return with an error, that error will be shown as well, 
% evaluation of further commands is cancelled, and the insertion point is 
% moved to the beginning of the erroneous command. Furthermore the mark 
% will be left at the end of the selection, so that the part of the 
% original selection which has not yet been successfully evaluated can 
% easily be reselected using the \textsf{Mark Hilite} command.
% 
% Loading \Tcllogo\ code does not necessary mean all text in the 
% selection will be evaluated; only extractable code will be passed on 
% to the \Tcllogo\ interpreter. There are several factors which affect 
% whether a piece of text is extractable code or not, but the foremost 
% is that text on \package{docstrip} comment lines (i.e., lines which 
% begin by a `|%|' that is not immediately followed by a `|<|') is 
% \emph{not} extractable code. Secondly, if the selection contains a 
% \package{docstrip} guard line which marks the start of a module then 
% \package{dtxload} will ask you whether you want the code in that 
% module to be loaded. If you answer no, it naturally won't be.
% 
% Thus far the factors which may restrict which text is extractable 
% code correspond exactly to what the \package{docstrip} 
% program~\cite{docstrip} might do when generating a file of extracted 
% code, but \package{dtxload} has two additional mechanisms which may 
% categorize text as ``not extractable code''. Both are however 
% controlled by preferences in the \Alpha\ \TeX\ mode, so they can be 
% switched off if you don't like them. 
% The first is the \describestring[var.][]{onlyLoadDtxFiles}
% \textsf{Only Load Dtx Files} preference, which when on restricts 
% loading to files with suffix \texttt{.dtx}. For \TeX\ files with other 
% suffixes I suspect that Command--L is pressed more often by accident 
% than because there actually is some \Tcllogo\ code that should be 
% loaded \textellipsis\space The second mechanism is controlled by the 
% \describestring[var.][]{onlyLoadTclEnvs} \textsf{Only Load Tcl Envs} 
% preference, which when on adds the restriction that extractable code 
% must appear inside a \texttt{tcl} or \texttt{tcl*} environment 
% (defined by the \package{tcldoc} \LaTeX\ package~\cite{tcldoc}). This 
% is primarily useful when a \texttt{.dtx} file contains both \Tcllogo\ 
% code in \texttt{tcl} environments and code in some other language in 
% e.g.\ \texttt{macrocode} environments, since if the preference had been 
% off then \package{dtxload} would stop at the \package{docstrip} guard 
% that must appear at the beginning of each non-\Tcllogo\ code section 
% and ask whether the code should be included, whereas if it is on then  
% \package{dtxload} doesn't even have to ask whether the code in the 
% \texttt{macrocode} environments should be loaded.
% 
% \medskip
% 
% As an example of how the load \Tcllogo\ code command works, consider 
% the following code:
% \DontCheckModules\iffalse
%<*example>
%<<EXAMPLE
% \fi\begin{macrocode}
% Text text text text text
% \begin{tcl}
set a A
%<*andB>
append a B
%</andB>
append a C
%<*andD>
append a D
%</andB>
expr $a
string length $a
% \end{tcl}
% text text text.
%    \end{macrocode}\iffalse
%EXAMPLE
%</example>
% \fi \CheckModules
% If lines 1--7 above are selected and Command--L is pressed, 
% \package{dtxload} will display the message ``\texttt{Tcl eval OK}'' on 
% the status line and the following information will have been added to 
% the log.\footnote{This shows the window log format, but there are 
% other formats. Furthermore the `\texttt{<}' and `\texttt{>}' will 
% actually be guillemets in \Alpha\ (but not in \AlphaTk).}
% \begin{trivlist}\item\small
%   |<dtxload> set a A|\\
%   |A|\\[\medskipamount]
%   |<dtxload> append a B|\\
%   |AB|\\[\medskipamount]
%   |<dtxload> append a C|\\
%   |ABC|
% \end{trivlist}
% The |<dtxload>| lines show the commands that were evaluated and the 
% lines after these contain the respective results of these commands. 
% Before the |append a B| command is evaluated, \package{dtxload} will 
% stop and ask
% \begin{quote}
%   \textsf{Should \textless andB\textgreater\ modules be included?}
% \end{quote}
% In the case above the answer given was `Yes'; if it had been `No' then 
% the |append a B| command would neither be logged nor evaluated, and 
% the result of the |append a C| command would have been |AC|.
% 
% If one continues by selecting lines 9--12 and pressing Command--L 
% then \package{dtxload} will display the message ``\texttt{Tcl eval 
% error}'' on the status line, the insertion point will be moved to the 
% beginning of line 11, and the following information will be found in 
% the log:
% \begin{trivlist}\item\small
%   |<dtxload> append a D|\\
%   |ABCD|\\[\medskipamount]
%   |<dtxload> expr $a|\\
%   |Error: syntax error in expression "ABCD"|
% \end{trivlist}
% If then line 11 is changed to |expr {$a}| and lines 11--12 are again 
% selected (e.g. using \textsf{Mark Hilite}) and loaded then 
% \package{dtxload} will log:
% \begin{trivlist}\item\small
%   |<dtxload> expr {$a}|\\
%   |ABCD|\\[\medskipamount]
%   |<dtxload> string length $a|\\
%   |4|
% \end{trivlist}
% 
% Finally, if lines 3--12 are selected and loaded then these are the 
% questions \package{dtxload} will ask:
% \begin{itemize}
%   \item \textsf{Should \textless andB\textgreater\ modules be included?}
%     (Possible answers are `Yes' and `No'.)
%   \item \textsf{Should \textless andD\textgreater\ modules be included?}
%     (Possible answers are `Yes' and `No'.)
%   \item \textsf{Module nesting error: \textless*andD\textgreater\ 
%          module ended by \textless/andB\textgreater. For which 
%          guards should the positions be pushed?}
%     (Possible answers are `None', `Start', `End', and `Both'.)
% \end{itemize}
% In the last case, \package{dtxload} has noticed that the guard 
% expressions that began (\textsf{andD}) and ended (\textsf{andB}) a 
% module are not equal (which is an error). Answering `Both' here will 
% push the positions of (the beginning of) both guard lines (8 and 10) onto 
% the bookmark stack so that they can easily be jumped to and corrected 
% later, but \package{dtxload} will continue evaluating the rest of the 
% selection after you answer.
% 
% 
% \subsection{Selecting log destination}
% 
% At startup, \package{dtxload} is logging results on the status line, 
% i.e., after a command has been evaluated it either displays the message
% \begin{quote}
%   \texttt{Tcl eval OK:\ }\meta{result}
% \end{quote}
% or
% \begin{quote}
%   \texttt{Tcl eval error:\ }\meta{error message}
% \end{quote}
% depending on whether the command returned an error or not. The 
% evaluation log can however be sent to a window instead.
% 
% To set the destination for the log, one uses the procedure 
% \describestring[proc][dtxload]{logdest}|dtxload::logdest|. To set the 
% log destination to the window \word{win}, one gives the command
% \begin{quote}
%   |dtxload::logdest window| \word{win}
% \end{quote}
% When the log destination is a window, the log shows the commands 
% that were evaluated as well as their result. If there is no window 
% named \word{win} then it is created. A slight 
% variation on this is the command
% \begin{quote}
%   |dtxload::logdest shell| \word{win}
% \end{quote}
% which makes the \word{win} window a \Alpha\ \Tcllogo\ shell window if 
% it has to create it. When the log destination is a shell window, the 
% commands that are executed will be saved on the history list as well 
% as inserted in the window.
% 
% A short form which may be convenient is
% \begin{quote}
%   |dtxload::logdest here|
% \end{quote}
% which simply makes the current window the log destination. Finally, 
% the log destination is reset to the status line after the command
% \begin{quote}
%   |dtxload::logdest status|
% \end{quote}
% Evaluation will also be logged on the status line if the log 
% destination window is closed.
% 
% 
% \subsection{Other features and surprises}
% 
% If nothing is selected when Command--L is pressed, \package{dtxload} 
% will continue as if all text was selected.
% 
% Like \Alpha's \Tcllogo\ shell, \package{dtxload} can send the commands 
% to evaluate to a remote \Tcllogo\ interpreter rather than \Alpha's 
% built-in interpreter. In both cases the choice of target interpreter is 
% controlled by the global \Alpha\ variable 
% \describestring[var.][]{evaluateRemotely}|evaluateRemotely|. The 
% easiest way of changing this variable is via the \Tcllogo-tk submenu 
% of \Alpha's \Tcllogo\ menu.
% 
% If the \textsf{Only Load Tcl Envs} preference is on and lines 4--6 in 
% the code example of Subsection~\ref{Ssec:Loading} are loaded then 
% \package{dtxload} will simply display the message
% \begin{quote}
%   \texttt{No extractable code found.}
% \end{quote}
% The reason for this is that the first character of the selection is 
% a |%|; when the first character in the interval to load is a percent 
% character then \package{dtxload} will guess that this position is not 
% in a \texttt{tcl} or \texttt{tcl*} environment, and therefore it won't 
% try to extract any code until it has seen a comment line that contains 
% |\begin{tcl}| or |\begin{tcl*}|. You can always avoid making a 
% \package{docstrip} guard the first thing in the selection to load.
% 
% 
% 
% \StopEventually{
%   \begin{thebibliography}{9}
%   \bibitem{Alphatk}
%     Vince Darley: \textit{Alphatk} ({\small WWW} page),
%     \texttt{http}://\texttt{www.santafe.edu}\slash
%    \texttt{\~{}vince}\slash \texttt{alphatk}\slash 
%    \texttt{about.html}
%   \bibitem{DocScriptingAlpha}
%     Donavan Hall: \textit{Alpha} ({\small WWW} page), 
%     \texttt{http}://\texttt{magnet.fsu.edu}\slash
%     \texttt{\~{}hall}\slash\texttt{docscripting}\slash
%     \texttt{alpha}/.
%   \bibitem{tcldoc}
%     Lars Hellstr\"om: 
%     \textit{The \package{tcldoc} package and class},
%     \texttt{ftp}:/\slash\texttt{ftp.tex.ac.uk}\slash
%     \texttt{tex-archive}\slash \texttt{macros}\slash 
%     \texttt{latex}\slash \texttt{contrib}\slash 
%     \texttt{supported}\slash \texttt{tcldoc.dtx}.
%   \bibitem{AlphaHome}
%     Pete Keleher: \textit{Alpha Home Page} ({\small WWW} page), 
%     \texttt{http}://\texttt{alpha.olm.net}/.
%   \bibitem{docstrip}
%     Frank Mittelbach, Denys Duchier, Johannes Braams, Marcin 
%     Woli\'nski, and Mark Wooding: \textit{The \textsf{DocStrip} 
%     program},  The \LaTeX3 Project; 
%     \texttt{ftp}:/\slash\texttt{ftp.tex.ac.uk}\slash
%     \texttt{tex-archive}\slash \texttt{macros}\slash 
%     \texttt{latex}\slash \texttt{base}\slash \texttt{docstrip.dtx}.
%   \end{thebibliography}  
% }
% 
% \section{Implementation}
% 
% 
% \subsection{Interface to \Alpha}
% 
% The package begins with an |alpha::feature| command to declare itself 
% to \Alpha. As it is hardly useful outside the \texttt{TeX} mode, it 
% declares itself as being specific to that mode.
% \begin{tcl}
%<*tcl>
alpha::feature dtxload 1.1 {TeX} {
% \end{tcl}
% 
% \begin{variable}{onlyLoadDtxFiles}
% \begin{variable}{onlyLoadTclEnvs}
%   Next comes the initialization script for the feature, which 
%   declares the two preference variables used by \package{dtxload}. 
%   Both variables are flags. |onlyLoadDtxFiles| is |1| if loading of 
%   code is restricted to files with suffix \texttt{.dtx} and |0| if 
%   there is no restriction. |onlyLoadTclEnvs| is |1| if only code 
%   surrounded by a \texttt{tcl} or \texttt{tcl*} environment is loaded 
%   and |0| if there is no such restriction. Both preferences are by 
%   default |1|.
%   \begin{tcl}
   # When set, the Load Tcl Code command will be disabled in
   # TeX files whose suffix is not dtx.
   newPref flag onlyLoadDtxFiles 1 TeX 
   # When set, the Load Tcl Code command will only extract code 
   # from code lines in tcl and tcl* environments.
   newPref flag onlyLoadTclEnvs 1 TeX 
%   \end{tcl}
% \end{variable}\end{variable}
% \begin{variable}{loadTclCode}
%   The initialization script also declares a keybinding preference (to 
%   the |dtxload::load| procedure), which is used for 
%   \package{dtxload}'s only command. The default value is Command--L 
%   and the binding is specific to the \texttt{TeX} mode.
%   \begin{tcl}
   # This is the key binding for dtxload's Load Tcl Code command.
   newPref binding loadTclCode <O/L TeX "" dtxload::load TeX
%   \end{tcl}
% \end{variable}
% 
% After the initialization script comes the activation and deactivation 
% scripts (which, if I understood things correctly, are called when 
% switching between modes), but these need not contain anything for 
% \package{dtxload}. Instead the arguments of |alpha::feature| continue 
% with the uninstallation procedure
% \begin{tcl}
} "" "" uninstall {this-file} \
% \end{tcl}
% the maintainer specification (|\x9a| is \texttt{\"{o}})
% \begin{tcl}
   maintainer {"Lars Hellstr\x9am" Lars.Hellstrom@math.umu.se} \
% \end{tcl}
% and a short help text
% \begin{tcl}
   help {The dtxload package implements a command for loading
      Tcl code that is embedded in a .dtx file without docstripping
      the file first. For more help, LaTeX the file dtxload.dtx.}
% \end{tcl}
% It is possible that the help should rather be |file dtxload.dtx|, but 
% then this file would have to be installed somewhere that \Alpha\ 
% would find it. I haven't studied the matter.
% 
% Next the |dtxload| namespace is declared to \Tcllogo.
% \begin{tcl}
namespace eval dtxload {}
% \end{tcl}
% \setnamespace{dtxload}
% 
% 
% \subsection{Code extraction}
% 
% 
% The code extraction algorithm of \package{dtxload} lack a few of the 
% features of proper \package{docstrip}, but I don't think any of them 
% are essential for the kind of work \package{dtxload} is designed for. 
% The differences to \package{docstrip} are:
% \begin{itemize}
%   \item The values of guard expressions are not determined from a 
%     base set of options, instead the user is inquired for the value of 
%     each guard expression.
%   \item Extraction of \package{docstrip} verbatim mode lines is not 
%     supported, but it isn't needed for \Tcllogo\ code either.
%   \item Metacomments aren't extracted, but they hardly contain any 
%     code of interest to the \Tcllogo\ interpreter anyway.
%   \item \package{dtxload} may scan the comment lines for certain 
%     known markup elements (beginning and end of \texttt{tcl} and 
%     \texttt{tcl*} environments) and choose to enable or disable 
%     extraction based on that.
% \end{itemize}
% \package{dtxload} does however act on the guard modifiers and it also 
% looks for errors in the syntax of guards.
% 
% \begin{variable}{module_stack}
% \begin{variable}{next_module_idx}
%   The |dtxload::module_stack| variable is keeps track of how modules 
%   are nested around the currently considered line. The variable is a 
%   stack implemented as a list in which the last element corresponds to 
%   the innermost module. Each element in this list is itself a list 
%   with the structure
%   \begin{quote}
%     \word{expression} \word{start pos.} \word{previous}\regopt
%   \end{quote}
%   The \word{expression} is the guard expression, as a string. The 
%   \word{start pos.} is the position in the file where the module 
%   started. Finally, the \word{previous} is a boolean value which 
%   records the inclusion status (value of |dtxload::module_included|) 
%   that was in force before the module was entered.
%   
%   The |dtxload::next_module_idx| variable holds the index in the 
%   |dtxload:|\penalty\hyphenpenalty|:module_stack| list of the next 
%   module whose expression has not yet been evaluated; it is equal to 
%   |llength ${dtxload::module_stack}| if all module expressions have 
%   been evaluated. Those elements in the |dtxload::module_stack| list 
%   which have index $\geq$ |dtxload::next_module_idx| do not have a 
%   \word{previous} element.
% \end{variable}\end{variable}
% 
% \begin{arrayvar}{known_expressions}[expression]
%   The |dtxload::known_expressions| array records the values of all 
%   known expressions, i.e., those expressions about whose values the 
%   user has been inquired. The entries are either |0| (for ``don't 
%   include'') or |1| (for ``include'').
% \end{arrayvar}
% 
% \begin{proc}{eval_guard}
%   The |dtxload::eval_guard| procedure takes the string that is a guard 
%   expression as argument. It returns |1| if the expression evaluates 
%   to true and |0| if it evaluates to false.
%   
%   If the expression has an entry in the |dtxload::known_expressions| 
%   array then the |dtxload::eval_guard| procedure returns that value, 
%   and if it does not the user is inquired for the value.
%   \begin{tcl}
proc dtxload::eval_guard {e} {
   global dtxload::known_expressions
   if {![info exists dtxload::known_expressions($e)]} then {
      set dtxload::known_expressions($e)\
         [expr {"yes" ==\
         "[askyesno "Should <$e> modules be included?"]"}]
   }
   set dtxload::known_expressions($e)
}
%   \end{tcl}
% \end{proc}
% 
% \begin{proc}{push_module}
%   The |dtxload::push_module| procedure pushes a block module onto the 
%   module stack, but it does not modify the value of 
%   |dtxload::module_included|. The syntax of |dtxload::push_module| is
%   \begin{quote}
%     |dtxload::push_module| \word{expression} \word{position}
%   \end{quote}
%   where \word{expression} is the expression string and 
%   \word{position} is the position where the guard begins.
%   \begin{tcl}
proc dtxload::push_module {e p} {
   global dtxload::module_stack
   lappend dtxload::module_stack [list $e $p]
}
%   \end{tcl}
% \end{proc}
% 
% \begin{proc}{pop_module}
%   The |dtxload::pop_module| procedure pops a block module off the 
%   module stack and checks that the modules are properly nested. Its 
%   syntax is
%   \begin{quote}
%     |dtxload::pop_module| \word{expression} \word{position}
%   \end{quote}
%   where \word{expression} is the expression string of the module to 
%   pop and \word{position} is the position where the (end of module) 
%   guard begins.
%   
%   If the module nesting is incorrect then the user is presented with 
%   a dialog with buttons for pushing the positions of the incorrect 
%   modules. It is not an error if the module stack is empty, since it 
%   is perfectly reasonable that the beginning of the code to evaluate 
%   is in the middle of a module.
%   \begin{tcl}
proc dtxload::pop_module {e p} {
   global dtxload::module_stack dtxload::module_included\
      dtxload::next_module_idx
   set len [llength ${dtxload::module_stack}]
   if {$len==0} then {return}
   set L [lindex ${dtxload::module_stack} [expr {$len-1}]]
   if {[lindex $L 0] != $e} then {
      switch [buttonAlert "Module nesting error: <*[lindex $L 0]>\
         module ended by </$e>. For which guards should the positions\
         be pushed?" None Start End Both]\
      {
         Start {dtxload::push_bookmarks [lindex $L 1]}
         End {dtxload::push_bookmarks $p}
         Both {dtxload::push_bookmarks [lindex $L 1] $p}
      }
   }
   set dtxload::module_stack\
      [lreplace ${dtxload::module_stack} end end]
   if {$len>=${dtxload::next_module_idx}} then {
      incr dtxload::next_module_idx -1
   }
   if {[llength $L]>2} then {
      set dtxload::module_included [lindex $L 2]
   }
}
%   \end{tcl}
% \end{proc}
% 
% \begin{proc}{push_bookmarks}
%   The |dtxload::push_bookmarks| procedure pushes one or several 
%   positions in the current window onto the bookmarks stack. The 
%   arguments are the positions to push.
%   \begin{tcl}
proc dtxload::push_bookmarks {args} {
   global markStack markName
   foreach pos $args {
      set name mark$markName
      incr markName
      createTMark $name $pos
      set fileName [win::Current]
      set markStack [linsert $markStack 0 [list $fileName $name]]
   }
}
%   \end{tcl}
% \end{proc}
% 
% \begin{variable}{module_included}
% \begin{variable}{in_tcl_env}
%   The |dtxload::module_included| variable keeps track of whether the 
%   current position is in an included module. It is |1| if the current 
%   position should be included and |0| if it shouldn't. 
%   The |dtxload::in_tcl_env| variable is used for keeping track of 
%   what markup context surrounds the currently considered line in the 
%   file. It is set to |1| when a |\begin{tcl}| or |\begin{tcl*}| is 
%   scanned, and set to |0| when a |\end{tcl}| or |\end{tcl*}| is scanned.
% \end{variable}\end{variable}
% 
% \begin{proc}{update_included}
%   Simply pushing a module onto the module stack does not update the 
%   |dtxload:|\penalty\hyphenpenalty|:module_included| variable; that is 
%   instead done by the |dtxload::update_included| procedure, which 
%   should be called right before the value of |dtxload::module_included| 
%   is used. The reason for this arrangement is that it avoids evaluating 
%   guard expressions whose values do not matter.
%   
%   |dtxload::update_included| has no arguments.
%   \begin{tcl}
proc dtxload::update_included {} {
   global dtxload::module_included dtxload::module_stack\
      dtxload::next_module_idx
   while {${dtxload::module_included} &&\
      ${dtxload::next_module_idx}<[llength ${dtxload::module_stack}]}\
   {
      set L [lindex ${dtxload::module_stack} ${dtxload::next_module_idx}]
      lappend L ${dtxload::module_included}
      set dtxload::module_stack [lreplace ${dtxload::module_stack}\
         ${dtxload::next_module_idx} ${dtxload::next_module_idx} $L]
      incr dtxload::next_module_idx
      set dtxload::module_included [dtxload::eval_guard [lindex $L 0]]
   }
}
%   \end{tcl}
% \end{proc}
%   
% 
% \begin{proc}{extract_line}
%   The |dtxload::extract_line| procedure steps forward in the file one 
%   line at a time until it has found a codeline that can be extracted or 
%   it reaches the end of the part of the file from which code is to be 
%   extracted. Its syntax is
%   \begin{quote}
%     |dtxload::extract_line| \word{startpos} \word{endpos}
%   \end{quote}
%   Here \word{startpos} is the position at which it should start to 
%   look for an extractable code line, and \word{endpos} is the 
%   position at which the search should stop if no such line is found. 
%   \word{startpos} is assumed to be at the beginning of a line (for 
%   identification of code, comment, and guard line purposes) but no 
%   test for this is made.
%   
%   The return value of |dtxload::extract_line| is a list with the 
%   structure
%   \begin{quote}
%     \word{nextpos} \word{line}\regopt\ \word{foundpos}\regopt
%   \end{quote}
%   \word{nextpos} is the first position in the file after the part that 
%   was searched. \word{line} is the extracted codeline and 
%   \word{foundpos} is the position at which it began, but these two items 
%   are missing if there was no more codeline.
%   
%   The overall structure of |dtxload::extract_line| is a loop 
%   which steps through the lines until it reaches the |endpos|. When a 
%   line to extract is actually found the procedure returns from within 
%   the loop using the |return| command. The local variable |pos| 
%   stores the current position, and |pos2| stores the position of the 
%   beginning of the next line.
%   \begin{tcl}
proc dtxload::extract_line {startpos endpos} {
   global dtxload::in_tcl_env onlyLoadTclEnvs dtxload::module_included
   for {set pos $startpos} {[pos::compare {$pos<$endpos}]}\
     {set pos $pos2} {
%   \end{tcl}
%   Inside the loop, the next line is extracted and stored in the local 
%   variable |line|. Then |switch| is used for classifying the line and 
%   taking appropriate actions.
%   \begin{tcl}
      set pos2 [nextLineStart $pos]
      if {$pos2>$endpos} then {set pos2 $endpos}
      set line [getText $pos $pos2]
      switch -regexp -- $line {
%   \end{tcl}
%   \changes{v\,1.0}{2000/10/15}{Corrected regular expressions; only 
%      percents on the beginning of a line are significant. (LH)}
%   \changes{v\,1.1}{2000/12/03}{Guard lines will affect code extraction. 
%      (LH)}
%   \changes{v\,1.1}{2000/12/18}{The code extraction procedures can 
%      now handle \package{docstrip} verbatim mode guards, provided 
%      they do not appear in a block of extractable code. (LH)}
%   Lines that begin with |%<<| are \package{docstrip} guard lines that 
%   start verbatim mode. Extracting code from such lines is currently 
%   not supported by \package{dtxload}, so if such a guard is ever 
%   encountered the extraction is stopped, but \package{dtxload} can 
%   skip verbatim sections from which it shouldn't extract code.
%   \begin{tcl}
         {^%<<} {
            if {!$onlyLoadTclEnvs || ${dtxload::in_tcl_env}} then {
               dtxload::update_included
               if {${dtxload::module_included}} then {
                  alertnote "docstrip verbatim mode guard line\
                     encountered. Verbatim mode extraction is\
                     currently not supported, so I stop here."
                  goto $pos
                  return [list $endpos]
               }
            }
%   \end{tcl}
%   The part of the guard line which comes after the |%<<| is called an 
%   end-tag. Verbatim mode ends with the next line which consists of a 
%   percent character followed by this end-tag, and therefore all lines 
%   up to and including that one are skipped. A technical matter here 
%   is that spaces at the end of the line does not count (\TeX\ cannot 
%   see them), but spaces inside the end-tag do count!
%   \begin{tcl}
            set endtag %[string trimright [string trimright\
               [string range $line 3 end] \n\r] \ ]
            while {[string trimright [string trimright $line \n\r] \ ]\
                   != $endtag} {
               set pos $pos2
               if {[pos::compare {$pos>=$endpos}]}\
               then {return [list $pos]}
               set pos2 [nextLineStart $pos]
               if {$pos2>$endpos} then {set pos2 $endpos}
               set line [getText $pos $pos2]
            }
         }
%   \end{tcl}
%   Lines that begin with |%<*| or |%</| are \package{docstrip} guard 
%   lines that delimit block modules, but they do not contain any code 
%   themselves. The module is pushed onto or popped off the module stack 
%   when the guard line is encountered, but evaluating it is deferred 
%   until the first extractable code line.
%   \begin{tcl}
         {^%<[*/]} {
            if {![regexp {^%<(\*|/)([^>]+)>} $line foo modifier\
               expression]}\
            then {
               if {"[askyesno "Malformed guard line \"$line\"\
                  encountered. Push position?"]"=="yes"}\
%
               then {dtxload::push_bookmarks $pos}
            } elseif {$modifier=="*"} then {
               dtxload::push_module $expression $pos
            } else {
               dtxload::pop_module $expression $pos
            }
         }
%   \end{tcl}
%   
%   Other lines that begin with |%<| are also \package{docstrip} 
%   guard lines, but in these cases the lines (i) contain some code 
%   and (ii) the guard only affect the code on that line. There must be 
%   a |>| somewhere on the line, and the part of the line after the |>| 
%   is code that \package{docstrip} can extract.
%   \begin{tcl}
         {^%<} {
            if {![regexp {^%<(-|\+|)([^>]+)>(.*)$} $line\
               foo modifier expression code]}\
            then {
               if {"[askyesno "Malformed guard line \"$line\"\
                  encountered. Push position?"]"=="yes"}\
%
               then {dtxload::push_bookmarks $pos}
            } elseif {!$onlyLoadTclEnvs || ${dtxload::in_tcl_env}} then {
               dtxload::update_included
               if {${dtxload::module_included}} then {
                  if {[dtxload::eval_guard $expression] !=\
                     ($modifier=="-")}\
                  then {return [list $pos2 $code $pos]}
               }
            }
         }
%   \end{tcl}
%   Remaining lines that begin with |%| are considered comment lines, 
%   but they could technically be metacomment lines (begin with |%%|) or 
%   a line that \package{docstrip} would process in verbatim mode. In 
%   both these cases \package{docstrip} would copy the line, but as there 
%   is little point in using these \package{docstrip} features for lines 
%   that the \Tcllogo\ interpreter would miss, \package{dtxload} ignores 
%   those subtleties.
%   \begin{tcl}
         {^%} {
            while {[regexp -indices {\\(begin|end) *{tcl\*?}} $line\
               match type]} {
               set dtxload::in_tcl_env\
                  [expr {"[eval string range \$line $type]"=="begin"}]
               set line [string range $line\
                  [expr {[lindex $match 1]+1}] end]
            }
         }
%   \end{tcl}
%   Finally, all lines that do not begin with a |%| are code lines.
%   \begin{tcl}
         default {
            if {!$onlyLoadTclEnvs || ${dtxload::in_tcl_env}} then {
               dtxload::update_included
               if {${dtxload::module_included}}\
%
               then {return [list $pos2 $line $pos]}
            }
         }
      }
   }
   list $endpos
}
%   \end{tcl}
% \end{proc}
% 
% 
% 
% \subsection{Evaluating the code}
% 
% The code in this subsection is based on the \Alpha\ procedures 
% |Alpha::evaluate| and |tcltk::evaluate|, but |dtxload::evaluate| 
% tries to return a bit more information.
% 
% \begin{proc}{evaluate}
%   The |dtxload::evaluate| procedure takes a script as argument and 
%   evaluates it in the global variable context. Any errors that occur 
%   are caught. The returned value is a list with the structure
%   \begin{quote}
%     \word{code} \word{message} 
%     \begin{regexp}[\regopt]\word{errorInfo} 
%     \word{errorCode}\end{regexp}
%   \end{quote}
%   \word{code} is the \Tcllogo\ return code, as returned by |catch| 
%   when evaluating the script. \word{message} is the value returned by 
%   the script; it is an error message if an error occurred. 
%   \word{errorInfo} is the value that the global variable |errorInfo| 
%   got after the script was evaluated and \word{errorCode} is the 
%   corresponding value of |errorCode|.
%   
%   When the \Alpha\ global variable |evaluateRemotely| is |0| the 
%   evaluation is carried out by \Alpha\ itself, but when 
%   |evaluateRemotely| is |1| the script is instead sent to a separate 
%   \Tcllogo\ shell for evaluation. The current implementation does not 
%   return the values of the |errorInfo| and |errorCode| variables in 
%   that case, which is why they may be absent from the return value of 
%   |dtxload::evaluate|.
%   \changes{v\,1.0}{2000/10/17}{Moved \texttt{history} interaction to 
%      \texttt{dtxload::shell\_log}. (LH)}
%   \changes{v\,1.1}{2000/12/05}{Added code for remote evaluation. (LH)}
%   \begin{tcl}
proc dtxload::evaluate {t} {
   global errorInfo errorCode evaluateRemotely tcl_platform
   if {!$evaluateRemotely} then {
      if {[set code [catch {uplevel \#0 $t} msg]] == 1} then {
%   \end{tcl}
%   If there was an error, the last part of the value of |errorInfo| 
%   will be due to the |uplevel| command. As that command was not 
%   requested by the user, it would be confusing and it is therefore 
%   best to remove it.
%   \begin{tcl}
         set L [split $errorInfo \n]
         set errorInfo [join [lrange $L 0 [expr {[llength $L] - 4}]] \n]
      }
      list $code $msg $errorInfo $errorCode
   } elseif {$tcl_platform(platform) == "macintosh"} then {
%   \end{tcl}
%   On the \mbox{MacOS} platform, the script is sent to a remote 
%   \Tcllogo\ shell via AppleEvents.
%   \begin{tcl}
      global tclshSig
      app::ensureRunning $tclshSig
      list [catch {
            aebuild::result -t 30000 '${tclshSig}' misc dosc ----\
               [aebuild::TEXT $t]
         } res]\
         $res
   } else {
%   \end{tcl}
%   On the other platforms I don't really know what should be done. The 
%   following code is based on that in |tcltk::evaluate|, but I haven't 
%   been able to test it (help, please?).
%   \begin{tcl}
      global tclshInterp
      if {![info exists tclshInterp]} {
          if {[catch {tcltk::findTclshInterp}]} {
              return [list 1 "No shell selected"]
          }
      }
      if {$tcl_platform(platform) == "windows"} {
          if {[dde services Tk $tclshInterp] == ""} {
              alertnote "The remote shell has died, please select a new one."
              unset tclshInterp
              return [dtxload::evaluate $t]
          }
          list [catch {dde execute Tk $tclshInterp $t} res] $res
      } else {
          list [catch {send $tclshInterp $t} res] $res
      }
   }
}
%   \end{tcl}
% \end{proc}
% 
% 
% \subsection{Logging}
% 
% The code in this subsection is based on the \Alpha\ procedures 
% |Shel::carriageReturn| and |Alpha::evaluate|, but many details had to 
% be changed because, amongst other things, the window to which text is 
% written is not the frontmost one.
% 
% \begin{proc}{message_log}
%   The |dtxload::message_log| procedure handles logging a script 
%   evaluation on the status line. It takes one argument, which is the 
%   script to evaluate, and returns a boolean value that specifies whether 
%   an error occurred (|0| is no error, |1| is that there was an error).
%   
%   Since the status line is rather limited in size there isn't very 
%   much that can be logged on it. |dtxload::message_log| simply displays 
%   the result or error that occurred.
%   \begin{tcl}
proc dtxload::message_log {script} {
   set res [dtxload::evaluate $script]
   if {[lindex $res 0]==1} then {
      message "Tcl eval error: [lindex $res 1]"
      expr 1
   } else {
      if {[string length [lindex $res 1]] == 0} then {
         message "Tcl eval OK."
      } else {
         message "Tcl eval OK: [lindex $res 1]"
      }
      expr 0
   }
}
%   \end{tcl}
% \end{proc}
% 
% 
% \begin{proc}{window_log}
%   \changes{v\,1.1}{2000/12/05}{Renamed procedure (old name was 
%      \texttt{dtxload:\discretionary{}{}{}:shell\_log}). (LH)}
% \begin{variable}{log_window_name}
%   \changes{v\,1.1}{2000/12/05}{Renamed variable (old name was 
%      \texttt{dtxload:\discretionary{}{}{}:shell\_window\_name}). (LH)}
%   The |dtxload::window_log| procedure handles logging a script 
%   evaluation in a window, which must be open when this procedure is 
%   called. It takes one argument, which is the script to evaluate, and 
%   returns a boolean value that specifies whether an error occurred 
%   (|0| is no error, |1| is that there was an error).
%   
%   When it is set the |dtxload::log_window_name| variable holds the 
%   name of the window which is used in logging, and when it isn't set 
%   this means that logging should be in the status line. Initially it 
%   is unset.
%   \begin{tcl}
if {[info exists dtxload::log_window_name]} then {
   unset dtxload::log_window_name
}
%   \end{tcl}
% \end{variable}
%   
%   If the log window has mode |Shel| then the |script| is recorded in 
%   the history list, but since the shells have trouble handling history 
%   items that contain more than one line, all newlines in the recorded 
%   script will be replaced by semicolons. This \emph{can} change the 
%   meaning of the script, but hopefully that happens so rarely that one 
%   can live with it.
%   \changes{v\,1.0}{2000/11/01}{Scripts added to the history list are 
%      converted to one-liners. (LH)}
%   \begin{tcl}
proc dtxload::window_log {script} {
   upvar #0 dtxload::log_window_name win 
   global win::Modes Shel::startPrompt Shel::endPrompt
   if {[set win::Modes($win)] == "Shel"} then {
      global Shel::histnum
      regsub -all \n [string trimright $script] " ; " text 
      history add $text
      set Shel::histnum [history nextid]
   }
%   \end{tcl}
%   
%   Next the script is inserted into (at the end of) the log window. 
%   The lines on which logged scripts are written are marked out using 
%   a special \package{dtxload} prompt, which is constructed as
%   \begin{quote}
%     |"${Shel::startPrompt}dtxload${Shel::endPrompt} "|
%   \end{quote}
%   If the log window mode is |Shel| and the last thing in the window 
%   is the current prompt for the window, then that prompt is replaced 
%   by the \package{dtxload} prompt, otherwise a newline followed by a 
%   \package{dtxload} prompt will be appended to the window. The result 
%   of a logged script is put on the line after the last line of the 
%   script.
%   \begin{tcl}
   set pos [maxPos -w $win]
   select -w $win $pos $pos
   set dtxprompt "${Shel::startPrompt}dtxload${Shel::endPrompt} "
   if {[set win::Modes($win)] != "Shel"} then {
      insertText -w $win \r$dtxprompt
   } else {
      set stdprompt [Alpha::Prompt]
      set pos2 [pos::math $pos - [string length $stdprompt]]
      if {[getText -w $win $pos2 $pos] != $stdprompt} then {
         insertText -w $win \r$dtxprompt
      } else {
         replaceText -w $win $pos2 $pos $dtxprompt
         refresh
      }
   }
%   \end{tcl}
%   There currently is a bug (it is fixed in \Alpha~8) in 
%   |replaceText| which causes it to always draw in the current window. 
%   The |refresh| restores the proper window contents.
%   \changes{v\,1.0}{2000/10/16}{\texttt{refresh} inserted to overcome 
%      \texttt{replaceText} bug. (LH)}
%   
%   Inserting the actual script text is basically an |insertText|, but 
%   before the script is inserted all newlines in it (except the last) 
%   are replaced by newlines followed by a \package{dtxload} prompt. 
%   Since |dtxload::load| converts all newlines to linefeeds, it is 
%   sufficient to replace linefeeds. It seems that newlines in \Alpha\ 
%   are always carriage returns (regardless of the window's ``platform'' 
%   attribute), and I assume that the \package{dtxload} prompt doesn't 
%   contain any regexp metacharacter.
%   \changes{v\,1.0}{2000/10/16}{Assuming newlines in the script to log 
%      are linefeeds. (LH)}
%   \begin{tcl}
   regsub -all \n [string trimright $script] \r$dtxprompt text 
   insertText -w $win "$text\r"
%   \end{tcl}
%   After the script has been logged, it is time to evaluate it and log 
%   the result.
%   \begin{tcl}
   set res [dtxload::evaluate $script]
   if {[lindex $res 0]==1} then {
      insertText -w $win "Error: [lindex $res 1]\r"
      if {[llength $res]>2} then {
         global errorInfo
         set errorInfo [lindex $res 2]
      }
      message "Tcl eval error"
   } else {
      if {[string length [lindex $res 1]]>0}\
      then {insertText -w $win "[lindex $res 1]\r"}
      message "Tcl eval OK"
   }
%   \end{tcl}
%   If the window has mode |Shel| then the window's current prompt is 
%   inserted. It is necessary to call |Alpha::Prompt| again because 
%   evaluating the script might have changed the prompt. Then the return 
%   value is finally computed.
%   \begin{tcl}
   if {[set win::Modes($win)] == "Shel"}\
   then {insertText -w $win [Alpha::Prompt]}
   expr {[lindex $res 0]==1}
}
%   \end{tcl}
% \end{proc}
% 
% 
% 
% 
% \subsection{Putting it all together}
% 
% \begin{proc}{load}
%   The |dtxload::load| procedure implements the \package{dtxload} user 
%   command---it extracts and evaluates the code in the current 
%   selection (if something is selected) or the entire front window (if 
%   nothing is selected). The evaluation is logged a window or on the 
%   status line depending on the current value of 
%   |dtxload::log_window_name|.
%   
%   Code is extracted and evaluated one command (or as close as one gets) 
%   at a time. In case an error occurs the loading is stopped and the 
%   insertion point is moved to the beginning of the problematic script, 
%   whereas the mark is put at the end of the code to load. This way a 
%   simple \textsf{Mark Hilite} will select the part of the code that 
%   remains to be loaded.
%   
%   The very first thing |dtxload::load| does is to check whether it is 
%   allowed to load any code in this window.
%   \begin{tcl}
proc dtxload::load {} {
   global onlyLoadDtxFiles
   if {$onlyLoadDtxFiles && ![string match *.dtx [win::CurrentTail]]}\
   then {
      message "Not a .dtx file."
      return
   }
%   \end{tcl}
%   Then the interval from which code should be extracted is 
%   determined.
%   \begin{tcl}
   set startpos [getPos]
   set endpos [selEnd]
   if {[pos::compare {$startpos == $endpos}]} then {
      set startpos [minPos]
      set endpos [maxPos]
   }
%   \end{tcl}
%   Next it is determined what logging method should be used. The name 
%   of the procedure gets stored in the local variable |log|.
%   \begin{tcl}
   global dtxload::log_window_name
   if {
      [info exists dtxload::log_window_name] &&
      [lsearch -exact [winNames] ${dtxload::log_window_name}]!=-1
   } then {set log dtxload::window_log}\
   else {set log dtxload::message_log}
%   \end{tcl}
%   After that a couple of extraction-related variables are initialized. 
%   The idea behind how the |dtxload::in_tcl_env| variable is set is that 
%   if one is loading a short piece of code inside a \texttt{tcl} 
%   environment then the first line probably doesn't start with a |%|, 
%   whereas if one is loading an entire file (and thus starts in 
%   non-\texttt{tcl}-environment) the first character quite likely is a 
%   |%|.
%   \begin{tcl}
   global dtxload::in_tcl_env dtxload::module_stack\
      dtxload::next_module_idx dtxload::module_included
   set dtxload::in_tcl_env\
     [expr {[getText $startpos [pos::math {$startpos+1}]] != "%"}]
   set dtxload::module_stack {}
   set dtxload::next_module_idx 0
   set dtxload::module_included 1
%   \end{tcl}
%   The last piece of initialization concerns the |script| local 
%   variable, in which the extracted lines are collected until they 
%   make up an entire command. The |escaped| variable is a boolean 
%   which is true when the newline at the end of the last line of 
%   |script| was escaped. The |spos| variable stores the position at 
%   which the command currently being collected began, but it is 
%   initialized to |none| here to help distinguishing the case that no 
%   extractable code was found.
%   \begin{tcl}
   set script ""
   set escaped 0
   set spos none
   while {[pos::compare $startpos < $endpos]} {
      set extract [dtxload::extract_line $startpos $endpos]
      if {[llength $extract]>1} then {
%   \end{tcl}
%   When a line of code has been extracted, it must be appended to 
%   |script|. This isn't as easy as one might imagine, because \Tcllogo\ 
%   code being |source|d (which is what loading must function as) is fed 
%   through a few more conversion steps than code being |eval|ed. In 
%   particular all escaped newlines are converted to spaces and all 
%   other newlines are converted to linefeeds, so that must be done 
%   explicitly. A newline is considered to be escaped if is is preceded 
%   by an odd number of backslashes, and if it is then the last backslash 
%   and the newline are replaced by a single space. If the last line of 
%   |script| ended by an escaped newline then the script is considered 
%   incomplete and more code will be collected before evaluation is 
%   attempted. Evaluation of |script| is also conditioned by that |info\
%   complete $script| returns |1|.
%   \changes{v\,1.0}{2000/10/16}{Converting nonescaped newlines to 
%      linefeeds, since \Tcllogo\ doesn't consider carriage returns to 
%      be command separators. (LH)}
%   \begin{tcl}
         if {[string length $script]==0} then {
            set spos [lindex $extract 2]
         }
         set line [lindex $extract 1]
         if {$escaped} then {set line [string trimleft $line]}
         set escaped [regsub -all\
            "((^|\[^\\\\\])(\\\\\\\\)*)\\\\(\r|\n|\r\n)$" $line {\1 } line]
         if {!$escaped} then {regsub "\r\n?\$" $line \n line}
         append script $line
         if {!$escaped && [info complete $script]} then {
            if {[$log $script]} then {
               select $spos $endpos
               markHilite
               return
            } else {
               set script ""
            }
         }
      } elseif {$spos=="none"} then {
         message "No extractable code found."
      }
      set startpos [lindex $extract 0]
   }
%   \end{tcl}
%   If the |script| variable isn't empty, then try to evaluate whatever 
%   is in it before returning. If not even that causes an error the 
%   |dtxload:|\penalty\hyphenpenalty|:known_expressions| array is unset 
%   so that one can use other options for the next piece of code loaded.
%   \begin{tcl}
   if {[string length $script]>0 && [$log $script]} then {
      select $spos $endpos
      markHilite
   } else {
      global dtxload::known_expressions
      if {[info exists dtxload::known_expressions]}\
      then {unset dtxload::known_expressions}
   }
}
%   \end{tcl}
% \end{proc}
% 
% 
% \subsection{Setting the log destination}
% 
% \begin{proc}{logdest}
%   \changes{v\,1.0}{2000/10/16}{Procedure added. (LH)}
%   \changes{v\,1.1}{2000/12/07}{Procedure renamed from 
%      \texttt{dtxload::redirect} and the syntax was changed. (LH)}
%   The log destination is set using the |dtxload::logdest| procedure. 
%   The general syntax for this procedure is
%   \begin{quote}
%     |dtxload::logdest| \word{keyword} \word{window name}\regopt
%   \end{quote}
%   where the \word{keyword} (mainly) specifies the type of log 
%   destination and \word{window name} is the name of the target 
%   window (ignored for some \word{keyword}s).
%   \begin{tcl}
proc dtxload::logdest {type {win "dtxload log"}} {
   global dtxload::log_window_name
   switch -exact -- $type {
%   \end{tcl}
%   The first form of |dtxload::logdest| has the syntax
%   \begin{quote}
%     |dtxload::logdest status|
%   \end{quote}
%   It makes the status line the log destination.
%   \begin{tcl}
      status {
         if {[info exists dtxload::log_window_name]}\
         then {unset dtxload::log_window_name}
      }
%   \end{tcl}
%   The second form has the syntax
%   \begin{quote}
%     |dtxload::logdest here|
%   \end{quote}
%   It makes the current window the log destination, regardless of what 
%   may already be in it or which mode it has.
%   \begin{tcl}
      here {set dtxload::log_window_name [win::CurrentTail]}
%   \end{tcl}
%   The third form has the syntax
%   \begin{quote}
%     |dtxload::logdest window| \word{window name}
%   \end{quote}
%   It sets the log destination to the window named \word{window name}, 
%   regardless of what may already be in it or which mode it has. If 
%   the window does not already exist it is created.
%   \begin{tcl}
      window {
        if {[lsearch -exact [winNames] $win] == -1} then {
            new -n $win -shell 1 -text "This is a dtxload log window.\r"
        }
        set dtxload::log_window_name $win
      }
%   \end{tcl}
%   The fourth and final form has the syntax
%   \begin{quote}
%     |dtxload::logdest shell| \word{window name}
%   \end{quote}
%   It calls |Shel::start| to open a \Tcllogo\ shell window and sets the 
%   log destination to that window.
%   \begin{tcl}
      shell {
        Shel::start "Alpha" $win\
           "This is a dtxload log window (and Alpha Tcl shell).\r"
        set dtxload::log_window_name $win
      }
   }
}
%</tcl>
%   \end{tcl}
% \end{proc}
% 
% 
% \Finale
% 
\endinput