package indirect;
-use 5.008;
+use 5.008001;
use strict;
use warnings;
=head1 VERSION
-Version 0.15
+Version 0.21
=cut
our $VERSION;
BEGIN {
- $VERSION = '0.15';
+ $VERSION = '0.21';
}
=head1 SYNOPSIS
my $z = new Pineapple 'fresh'; # croaks 'You really wanted Pineapple->new at blurp.pm:13'
}
}
+ try { ... }; # warns
+
no indirect ':fatal';
if (defied $foo) { ... } # croaks, note the typo
=head1 DESCRIPTION
When enabled (or disabled as some may prefer to say, since you actually turn it on by calling C<no indirect>), this pragma warns about indirect object syntax constructs that may have slipped into your code.
+
This syntax is now considered harmful, since its parsing has many quirks and its use is error prone (when C<swoosh> isn't defined, C<swoosh $x> actually compiles to C<< $x->swoosh >>).
+In L<http://www.shadowcat.co.uk/blog/matt-s-trout/indirect-but-still-fatal>, Matt S. Trout gives an example of an indirect construct that can cause a particularly bewildering error.
-It currently does not warn when the object is enclosed between braces (like C<meth { $obj } @args>) or for core functions (C<print> or C<say>).
+It currently does not warn for core functions (C<print>, C<say>, C<exec> or C<system>).
This may change in the future, or may be added as optional features that would be enabled by passing options to C<unimport>.
This module is B<not> a source filter.
=cut
BEGIN {
- require XSLoader;
- XSLoader::load(__PACKAGE__, $VERSION);
+ if ($ENV{PERL_INDIRECT_PM_DISABLE}) {
+ *_tag = sub ($) { 1 };
+ *I_THREADSAFE = sub () { 1 };
+ *I_FORKSAFE = sub () { 1 };
+ } else {
+ require XSLoader;
+ XSLoader::load(__PACKAGE__, $VERSION);
+ }
}
=head1 METHODS
=item *
-If the key/value pair C<< hook => $hook >> comes first, C<$hook> will be called for each error with the object name as C<$_[0]>, the method name as C<$_[1]>, the current file as C<$_[2]> and the line number as C<$_[3]>.
+If the key/value pair C<< hook => $hook >> comes first, C<$hook> will be called for each error with a string representation of the object as C<$_[0]>, the method name as C<$_[1]>, the current file as C<$_[2]> and the line number as C<$_[3]>.
+If and only if the object is actually a block, C<$_[0]> is assured to start by C<'{'>.
=item *
=cut
-my $msg = sub {
- "Indirect call of method \"$_[1]\" on object \"$_[0]\" at $_[2] line $_[3].\n"
-};
-
sub unimport {
shift;
if ($arg eq 'hook') {
$hook = shift;
} elsif ($arg eq ':fatal') {
- $hook = sub { die $msg->(@_) };
+ $hook = sub { die msg(@_) };
}
last if $hook;
}
- $hook = sub { warn $msg->(@_) } unless defined $hook;
+ $hook = sub { warn msg(@_) } unless defined $hook;
$^H |= 0x00020000;
$^H{+(__PACKAGE__)} = _tag($hook);
();
}
+=head1 FUNCTIONS
+
+=head2 C<msg $object, $method, $file, $line>
+
+Returns the default error message generated by C<indirect> when an invalid construct is reported.
+
+=cut
+
+sub msg {
+ my $obj = $_[0];
+
+ join ' ', "Indirect call of method \"$_[1]\" on",
+ ($obj =~ /^\s*\{/ ? "a block" : "object \"$obj\""),
+ "at $_[2] line $_[3].\n";
+};
+
=head1 CONSTANTS
=head2 C<I_THREADSAFE>
True iff the module could have been built with thread-safety features enabled.
+=head2 C<I_FORKSAFE>
+
+True iff this module could have been built with fork-safety features enabled.
+This will always be true except on Windows where it's false for perl 5.10.0 and below .
+
+=head1 DIAGNOSTICS
+
+=head2 C<Indirect call of method "%s" on object "%s" at %s line %d.>
+
+The default warning/exception message thrown when an indirect call on an object is found.
+
+=head2 C<Indirect call of method "%s" on a block at %s line %d.>
+
+The default warning/exception message thrown when an indirect call on a block is found.
+
+=head1 ENVIRONMENT
+
+=head2 C<PERL_INDIRECT_PM_DISABLE>
+
+If this environment variable is set to true when the pragma is used for the first time, the XS code won't be loaded and, although the C<'indirect'> lexical hint will be set to true in the scope of use, the pragma itself won't do anything.
+In this case, the pragma will always be considered to be thread-safe, and as such L</I_THREADSAFE> will be true.
+This is useful for disabling C<indirect> in production environments.
+
+Note that clearing this variable after C<indirect> was loaded has no effect.
+If you want to reenable the pragma later, you also need to reload it by deleting the C<'indirect.pm'> entry from C<%INC>.
+
=head1 CAVEATS
The implementation was tweaked to work around several limitations of vanilla C<perl> pragmas : it's thread safe, and doesn't suffer from a C<perl 5.8.x-5.10.0> bug that causes all pragmas to propagate into C<require>d scopes.
With 5.8 perls, the pragma does not propagate into C<eval STRING>.
This is due to a shortcoming in the way perl handles the hints hash, which is addressed in perl 5.10.
+The search for indirect method calls happens before constant folding.
+Hence C<my $x = new Class if 0> will be caught.
+
=head1 DEPENDENCIES
-L<perl> 5.8.
+L<perl> 5.8.1.
L<XSLoader> (standard since perl 5.006).
Bram, for motivation and advices.
+Andrew Main and Florian Ragwitz, for testing on real-life code and reporting issues.
+
=head1 COPYRIGHT & LICENSE
-Copyright 2008-2009 Vincent Pit, all rights reserved.
+Copyright 2008,2009,2010 Vincent Pit, all rights reserved.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
projects / perl / modules / indirect.git / blobdiff