diff options
Diffstat (limited to 'Master/tlpkg/tlperl.straw/lib/pods/perlclib.pod')
| -rwxr-xr-x | Master/tlpkg/tlperl.straw/lib/pods/perlclib.pod | 212 |
1 files changed, 212 insertions, 0 deletions
diff --git a/Master/tlpkg/tlperl.straw/lib/pods/perlclib.pod b/Master/tlpkg/tlperl.straw/lib/pods/perlclib.pod new file mode 100755 index 00000000000..39488f0fa67 --- /dev/null +++ b/Master/tlpkg/tlperl.straw/lib/pods/perlclib.pod @@ -0,0 +1,212 @@ +=head1 NAME + +perlclib - Internal replacements for standard C library functions + +=head1 DESCRIPTION + +One thing Perl porters should note is that F<perl> doesn't tend to use that +much of the C standard library internally; you'll see very little use of, +for example, the F<ctype.h> functions in there. This is because Perl +tends to reimplement or abstract standard library functions, so that we +know exactly how they're going to operate. + +This is a reference card for people who are familiar with the C library +and who want to do things the Perl way; to tell them which functions +they ought to use instead of the more normal C functions. + +=head2 Conventions + +In the following tables: + +=over 3 + +=item C<t> + +is a type. + +=item C<p> + +is a pointer. + +=item C<n> + +is a number. + +=item C<s> + +is a string. + +=back + +C<sv>, C<av>, C<hv>, etc. represent variables of their respective types. + +=head2 File Operations + +Instead of the F<stdio.h> functions, you should use the Perl abstraction +layer. Instead of C<FILE*> types, you need to be handling C<PerlIO*> +types. Don't forget that with the new PerlIO layered I/O abstraction +C<FILE*> types may not even be available. See also the C<perlapio> +documentation for more information about the following functions: + + Instead Of: Use: + + stdin PerlIO_stdin() + stdout PerlIO_stdout() + stderr PerlIO_stderr() + + fopen(fn, mode) PerlIO_open(fn, mode) + freopen(fn, mode, stream) PerlIO_reopen(fn, mode, perlio) (Deprecated) + fflush(stream) PerlIO_flush(perlio) + fclose(stream) PerlIO_close(perlio) + +=head2 File Input and Output + + Instead Of: Use: + + fprintf(stream, fmt, ...) PerlIO_printf(perlio, fmt, ...) + + [f]getc(stream) PerlIO_getc(perlio) + [f]putc(stream, n) PerlIO_putc(perlio, n) + ungetc(n, stream) PerlIO_ungetc(perlio, n) + +Note that the PerlIO equivalents of C<fread> and C<fwrite> are slightly +different from their C library counterparts: + + fread(p, size, n, stream) PerlIO_read(perlio, buf, numbytes) + fwrite(p, size, n, stream) PerlIO_write(perlio, buf, numbytes) + + fputs(s, stream) PerlIO_puts(perlio, s) + +There is no equivalent to C<fgets>; one should use C<sv_gets> instead: + + fgets(s, n, stream) sv_gets(sv, perlio, append) + +=head2 File Positioning + + Instead Of: Use: + + feof(stream) PerlIO_eof(perlio) + fseek(stream, n, whence) PerlIO_seek(perlio, n, whence) + rewind(stream) PerlIO_rewind(perlio) + + fgetpos(stream, p) PerlIO_getpos(perlio, sv) + fsetpos(stream, p) PerlIO_setpos(perlio, sv) + + ferror(stream) PerlIO_error(perlio) + clearerr(stream) PerlIO_clearerr(perlio) + +=head2 Memory Management and String Handling + + Instead Of: Use: + + t* p = malloc(n) Newx(id, p, n, t) + t* p = calloc(n, s) Newxz(id, p, n, t) + p = realloc(p, n) Renew(p, n, t) + memcpy(dst, src, n) Copy(src, dst, n, t) + memmove(dst, src, n) Move(src, dst, n, t) + memcpy(dst, src, sizeof(t)) StructCopy(src, dst, t) + memset(dst, 0, n * sizeof(t)) Zero(dst, n, t) + memzero(dst, 0) Zero(dst, n, char) + free(p) Safefree(p) + + strdup(p) savepv(p) + strndup(p, n) savepvn(p, n) (Hey, strndup doesn't exist!) + + strstr(big, little) instr(big, little) + strcmp(s1, s2) strLE(s1, s2) / strEQ(s1, s2) / strGT(s1,s2) + strncmp(s1, s2, n) strnNE(s1, s2, n) / strnEQ(s1, s2, n) + +Notice the different order of arguments to C<Copy> and C<Move> than used +in C<memcpy> and C<memmove>. + +Most of the time, though, you'll want to be dealing with SVs internally +instead of raw C<char *> strings: + + strlen(s) sv_len(sv) + strcpy(dt, src) sv_setpv(sv, s) + strncpy(dt, src, n) sv_setpvn(sv, s, n) + strcat(dt, src) sv_catpv(sv, s) + strncat(dt, src) sv_catpvn(sv, s) + sprintf(s, fmt, ...) sv_setpvf(sv, fmt, ...) + +Note also the existence of C<sv_catpvf> and C<sv_vcatpvfn>, combining +concatenation with formatting. + +Sometimes instead of zeroing the allocated heap by using Newxz() you +should consider "poisoning" the data. This means writing a bit +pattern into it that should be illegal as pointers (and floating point +numbers), and also hopefully surprising enough as integers, so that +any code attempting to use the data without forethought will break +sooner rather than later. Poisoning can be done using the Poison() +macros, which have similar arguments as Zero(): + + PoisonWith(dst, n, t, b) scribble memory with byte b + PoisonNew(dst, n, t) equal to PoisonWith(dst, n, t, 0xAB) + PoisonFree(dst, n, t) equal to PoisonWith(dst, n, t, 0xEF) + Poison(dst, n, t) equal to PoisonFree(dst, n, t) + +=head2 Character Class Tests + +There are two types of character class tests that Perl implements: one +type deals in C<char>s and are thus B<not> Unicode aware (and hence +deprecated unless you B<know> you should use them) and the other type +deal in C<UV>s and know about Unicode properties. In the following +table, C<c> is a C<char>, and C<u> is a Unicode codepoint. + + Instead Of: Use: But better use: + + isalnum(c) isALNUM(c) isALNUM_uni(u) + isalpha(c) isALPHA(c) isALPHA_uni(u) + iscntrl(c) isCNTRL(c) isCNTRL_uni(u) + isdigit(c) isDIGIT(c) isDIGIT_uni(u) + isgraph(c) isGRAPH(c) isGRAPH_uni(u) + islower(c) isLOWER(c) isLOWER_uni(u) + isprint(c) isPRINT(c) isPRINT_uni(u) + ispunct(c) isPUNCT(c) isPUNCT_uni(u) + isspace(c) isSPACE(c) isSPACE_uni(u) + isupper(c) isUPPER(c) isUPPER_uni(u) + isxdigit(c) isXDIGIT(c) isXDIGIT_uni(u) + + tolower(c) toLOWER(c) toLOWER_uni(u) + toupper(c) toUPPER(c) toUPPER_uni(u) + +=head2 F<stdlib.h> functions + + Instead Of: Use: + + atof(s) Atof(s) + atol(s) Atol(s) + strtod(s, &p) Nothing. Just don't use it. + strtol(s, &p, n) Strtol(s, &p, n) + strtoul(s, &p, n) Strtoul(s, &p, n) + +Notice also the C<grok_bin>, C<grok_hex>, and C<grok_oct> functions in +F<numeric.c> for converting strings representing numbers in the respective +bases into C<NV>s. + +In theory C<Strtol> and C<Strtoul> may not be defined if the machine perl is +built on doesn't actually have strtol and strtoul. But as those 2 +functions are part of the 1989 ANSI C spec we suspect you'll find them +everywhere by now. + + int rand() double Drand01() + srand(n) { seedDrand01((Rand_seed_t)n); + PL_srand_called = TRUE; } + + exit(n) my_exit(n) + system(s) Don't. Look at pp_system or use my_popen + + getenv(s) PerlEnv_getenv(s) + setenv(s, val) my_putenv(s, val) + +=head2 Miscellaneous functions + +You should not even B<want> to use F<setjmp.h> functions, but if you +think you do, use the C<JMPENV> stack in F<scope.h> instead. + +For C<signal>/C<sigaction>, use C<rsignal(signo, handler)>. + +=head1 SEE ALSO + +C<perlapi>, C<perlapio>, C<perlguts> + |