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Devel::Hints - Access compile-time hints at runtime
This document describes version 0.21 of Devel::Hints, released November
10, 2010.
use Devel::Hints ':all';
print cop_label(); # 'LABEL'
# cop_label is only settable on Perl 5.8 or below
cop_label(0 => 'FOO'); # "goto FOO;" is valid after this point!
print cop_file(); # same as __FILE__
print cop_filegv(); # same as \$::{'_<' . __FILE__}
print cop_stashpv(); # same as __PACKAGE__
print cop_stash(); # same as \%{__PACKAGE__ . '::'}
print cop_seq(); # an integer
print cop_arybase(); # same as $[
print cop_line(); # same as __LINE__
# cop_warnings() is only available to Perl 5.8 or below
use warnings;
print cop_warnings(); # same as compile-time ${^WARNING_BITS}
# cop_io() is only available to Perl 5.7 and Perl 5.8
use open IO => ':utf8';
print cop_io(); # same as compile-time ${^OPEN}
use IO => ':raw';
print cop_io(1); # access one uplevel; still ":utf8\0:utf8"
This module exports the "cop" (code operator) struct as individual
functions; callers can call them to find out the lexical-scoped hints
that its block (or statement) is compiled under.
No functions are exported by default. Each function may take an optional
positive integer as argument, indicating how many blocks it should walk
upward to obtain the "cop" members.
Functions can also take another optional argument, which (if specified)
*becomes the new value* for the hint, affecting the current statement or
block's behaviour.
On perl 5.10 or greater, the first argument to these functions can also
be a coderef. In that case, they return the value for the first
statement in the coderef's body, and if an argument is passed, they set
the value for the entire coderef body. "cop_line" and "cop_file" are
slightly special here - #line directives within the coderef will still
be respected, and the line will be offset by the correct amount within
the sub.
Label for the current construct.
File name for the current source file.
Glob reference to the current source filehandle.
The current package name.
Hash reference to the current symbol table.
Parse sequencial number.
Array base the calling line was compiled with.
The line number.
Lexical warnings bitmask, a.k.a. "${^WARNING_BITS}". If no lexical
warnings are in effect, returns the global warning flags as an
Lexical IO defaults, a.k.a. "${^OPEN}". If no lexical IO layers are
in effect, an empty string is returned. Always returns "undef" under
pre-5.7 versions of Perl.
Thanks to Rafael Garcia-Suarez for demonstrating how to do this with the
elegant Inline::C code on p5p, which I adapted to this less elegant XS
唐鳳 <>
CC0 1.0 Universal
To the extent possible under law, 唐鳳 has waived all copyright and
related or neighboring rights to Devel-Hints.
This work is published from Taiwan.