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diff --git a/Master/tlpkg/tlperl/lib/Tk/option.pod b/Master/tlpkg/tlperl/lib/Tk/option.pod new file mode 100644 index 00000000000..1214357d181 --- /dev/null +++ b/Master/tlpkg/tlperl/lib/Tk/option.pod @@ -0,0 +1,217 @@ +# Copyright (c) 1990 The Regents of the University of California. +# Copyright (c) 1994-1996 Sun Microsystems, Inc. +# See the file "license.terms" for information on usage and redistribution +# of this file, and for a DISCLAIMER OF ALL WARRANTIES. +# +# + +=head1 NAME + +option - Using the option database in Perl/Tk + +=for category Creating and Configuring Widgets + +=head1 SYNOPSIS + +S< >I<$widget>-E<gt>B<widgetClass>(B<Name>=E<gt>I<name>, B<-class>=E<gt>I<class>); + +S< >I<$widget>-E<gt>B<PathName>; + +S< >I<$widget>-E<gt>B<optionAdd>(I<pattern>=E<gt>I<value > ?,I<priority>?); + +S< >I<$widget>-E<gt>B<optionClear>; + +S< >I<$widget>-E<gt>B<optionGet>(I<name, class>); + +S< >I<$widget>-E<gt>B<optionReadfile>(I<fileName> ?,I<priority>?); + +=head1 DESCRIPTION + +The option database (also known as the I<resource database> or the +I<application defaults database>) is a set of rules for applying +default options to widgets. Users and system administrators can +set up these rules to customize the appearance of applications +without changing any application code; for example, a user might +set up personal foreground and background colors, or a site +might use fonts associated with visual or language preferences. +Different window managers (and implementations of them) have implemented +the database differently, but most Xt-based window managers use the +I<.Xdefaults> file or the I<xrdb> utility to manage user preferences; +some use both, and/or implement a more complex set of site, user and +application databases. Check your site documentation for these topics +or your window manager's B<RESOURCE_MANAGER> property. + +=head2 Being a good citizen + +For most applications, the option database "just works." The B<option...> +methods are for applications that need to do something unusual, such as +add new rules or test an option's default. Even in such cases, the +application should provide for user preferences. +Do not hardcode widget options without a B<very> good reason. +All users have their own tastes and they are all different. +They choose a special font in a special size and have often spend a +lot of time working out a color scheme that they will love until death. +When you respect their choices they will enjoy working with your +applications much more. Don't destroy the common look and feel of a +personal desktop. + +=head2 Option rules and widget identification + +All widgets in an application are identified hierarchically by I<pathname>, +starting from the B<MainWindow> and passing through each widget used to create +the endpoint. The path elements are I<widget names>, much like the elements +of a file path from the root directory to a file. The rules in the option +database are patterns that are matched against a widget's I<pathname> to +determine which defaults apply. +When a widget is created, the B<Name> option can be +used to assign the widget's name and thus create a distinctive path +for widgets in an application. If the B<Name> option isn't given, +Perl/Tk assigns a default name based on the type of widget; a +B<MainWindow>'s default name is the B<appname>. These defaults are fine +for most widgets, so don't feel you need to find a meaningful name for +every widget you create. +A widget must have a distinctive name to allow users to tailor its +options independently of other widgets in an application. For instance, +to create a B<Text> widget that will +have special options assigned to it, give it a name such as: + + $text = $mw->Text(Name => 'importantText'); + +You can then tailor the widget's attributes with a rule in the option +database such as: + + *importantText*foreground: red + +The I<class> attribute identifies groups of widgets, usually within an +application but also to group similar widgets among different applications. +One typically assigns a class to a B<TopLevel> or B<Frame> so that the +class will apply to all of that widget's children. To extend the example, +we could be more specific about the importantText widget +by giving its frame a class: + + $frame = $mw->Frame(-class => 'Urgent'); + $text = $frame->Text(Name => 'importantText'); + +Then the resource pattern can be specified as so: + + *Urgent*importantText*foreground: red + +Similarly, the pattern C<*Urgent*background: cyan> would apply to all +widgets in the frame. + +=head1 METHODS + +=over 4 + +=item I<$widget>-E<gt>B<widgetClass>(B<Name>=E<gt>I<name>, B<-class>=E<gt>I<class>); + +Identify a new widget with I<name> and/or I<class>. +B<Name> specifies the path element for the widget; names generally begin with a +lowercase letter. B<-class> specifies the class for the widget and its +children; classes generally begin with an uppercase letter. +If not specified, Perl/Tk will assign a unique default name to each widget. +Only B<MainWindow> widgets have a default class, made by uppercasing the +first letter of the application name. + +=item I<$widget>-E<gt>B<PathName>; + +The B<PathName> method returns the widget's I<pathname>, which uniquely +identifies the widget within the application. + +=item I<$widget>-E<gt>B<optionAdd>(I<pattern>=E<gt>I<value >?, I<priority>?); + +The B<optionAdd> method adds a new option to the database. +I<Pattern> contains the option being specified, and consists of +names and/or classes separated by asterisks or dots, in the usual +X format. I<Value> contains a text string to associate with +I<pattern>; this is the value that will be returned in calls to +the B<optionGet> method. If I<priority> is specified, it indicates +the priority level for this option (see below for legal values); +it defaults to B<interactive>. This method always returns an empty +string. + +=item I<$widget>-E<gt>B<optionClear>; + +The B<optionClear> method clears the option database. Default +options (from the B<RESOURCE_MANAGER> property or the B<.Xdefaults> +file) will be reloaded automatically the next time an option is +added to the database or removed from it. This method always returns +an empty string. + +=item I<$widget>-E<gt>B<optionGet>(I<name,class>); + +The B<optionGet> method returns the value of the option specified for +I<$widget> under I<name> and I<class>. To look up the option, +B<optionGet> matches the patterns in the resource database against +I<$widget>'s I<pathname> along with the class of I<$widget> +(or its parent if I<$widget> has no class specified). The widget's +class and name are options set when the widget is created (not +related to class in the sense of L<bless>); the B<MainWindow>'s name +is the B<appname> and its class is (by default) derived from the name +of the script. + +If several entries in the option database match I<$widget>'s I<pathname>, +I<name>, and I<class>, then the method returns whichever was created with +highest I<priority> level. If there are several matching +entries at the same priority level, then it returns whichever entry +was I<most recently entered> into the option database. If there are +no matching entries, then the empty string is returned. + +=item I<$widget>-E<gt>B<optionReadfile>(I<fileName>?,I<priority>?); + +The B<optionReadfile> method reads I<fileName>, which should have the +standard format for an X resource database such as B<.Xdefaults>, and +adds all the options specified in that file to the option database. +If I<priority> is specified, it indicates the priority level at which +to enter the options; I<priority> defaults to B<interactive>. + +The I<priority> arguments to the B<option> methods are +normally specified symbolically using one of the following values: + +=over 8 + +=item B<widgetDefault> + +Level 20. Used for default values hard-coded into widgets. + +=item B<startupFile> + +Level 40. Used for options specified in application-specific +startup files. + +=item B<userDefault> + +Level 60. Used for options specified in user-specific defaults +files, such as B<.Xdefaults>, resource databases loaded into +the X server, or user-specific startup files. + +=item B<interactive> + +Level 80. Used for options specified interactively after the application +starts running. If I<priority> isn't specified, it defaults to +this level. + +=back + +Any of the above keywords may be abbreviated. In addition, priorities +may be specified numerically using integers between 0 and 100, +inclusive. The numeric form is probably a bad idea except for new priority +levels other than the ones given above. + +=back + +=head1 BUGS + +The priority scheme used by core Tk is not the same as used by normal Xlib +routines. In particular is assumes that the order of the entries is defined, +but user commands like B<xrdb -merge> can change the order. + +=head1 SEE ALSO + +L<Tk::Xrm|Tk::Xrm> + +=head1 KEYWORDS + +database, option, priority, retrieve + +=cut |