diff options
| -rw-r--r-- | pod/perlsub.pod | 24 | ||||
| -rw-r--r-- | pp.c | 3 | ||||
| -rw-r--r-- | toke.c | 4 |
3 files changed, 29 insertions, 2 deletions
diff --git a/pod/perlsub.pod b/pod/perlsub.pod index 4329c161ff..efadf8f848 100644 --- a/pod/perlsub.pod +++ b/pod/perlsub.pod @@ -1194,6 +1194,30 @@ a properly written override. For a fully functional example of overriding C<glob>, study the implementation of C<File::DosGlob> in the standard library. +When you override a built-in, your replacement should be consistent (if +possible) with the built-in native syntax. You can achieve this by using +a suitable prototype. To get the prototype of an overridable built-in, +use the C<prototype> function with an argument of C<"CORE::builtin_name"> +(see L<perlfunc/prototype>). + +Note however that some built-ins can't have their syntax expressed by a +prototype (such as C<system> or C<chomp>). If you override them you won't +be able to fully mimic their original syntax. + +The built-ins C<do>, C<require> and C<glob> can also be overriden, but due +to special magic, their original syntax is preserved, and you don't have +to define a prototype for their replacements. (You can't override the +C<do BLOCK> syntax, though). + +C<require> has special additional dark magic: if you invoke your +C<require> replacement as C<require Foo::Bar>, it will actually receive +the argument C<"Foo/Bar.pm"> in @_. See L<perlfunc/require>. + +And, as you'll have noticed from the previous example, if you override +C<glob>, the C<E<lt>*E<gt>> glob operator is overriden as well. + +Finally, some built-ins (e.g. C<exists> or C<grep>) can't be overriden. + =head2 Autoloading If you call a subroutine that is undefined, you would ordinarily @@ -15,6 +15,7 @@ #include "EXTERN.h" #define PERL_IN_PP_C #include "perl.h" +#include "keywords.h" /* variations on pp_null */ @@ -365,6 +366,8 @@ PP(pp_prototype) I32 oa; char str[ MAX_ARGS_OP * 2 + 2 ]; /* One ';', one '\0' */ + if (code == -KEY_chop || code == -KEY_chomp) + goto set; while (i < MAXO) { /* The slow way. */ if (strEQ(s + 6, PL_op_name[i]) || strEQ(s + 6, PL_op_desc[i])) @@ -5330,12 +5330,12 @@ Perl_keyword(pTHX_ register char *d, I32 len) if (strEQ(d,"cos")) return -KEY_cos; break; case 4: - if (strEQ(d,"chop")) return KEY_chop; + if (strEQ(d,"chop")) return -KEY_chop; break; case 5: if (strEQ(d,"close")) return -KEY_close; if (strEQ(d,"chdir")) return -KEY_chdir; - if (strEQ(d,"chomp")) return KEY_chomp; + if (strEQ(d,"chomp")) return -KEY_chomp; if (strEQ(d,"chmod")) return -KEY_chmod; if (strEQ(d,"chown")) return -KEY_chown; if (strEQ(d,"crypt")) return -KEY_crypt; |