package indirect;
-use 5.008001;
+use 5.008_001;
use strict;
use warnings;
=head1 NAME
-indirect - Lexically warn about using the indirect object syntax.
+indirect - Lexically warn about using the indirect method call syntax.
=head1 VERSION
-Version 0.25
+Version 0.38
=cut
our $VERSION;
BEGIN {
- $VERSION = '0.25';
+ $VERSION = '0.38';
}
=head1 SYNOPSIS
- # In a script
- no indirect;
+In a script :
+
+ no indirect; # lexically enables the pragma
my $x = new Apple 1, 2, 3; # warns
{
- use indirect;
- my $y = new Pear; # ok
+ use indirect; # lexically disables the pragma
+ my $y = new Pear; # legit, does not warn
{
+ # lexically specify an hook called for each indirect construct
no indirect hook => sub {
die "You really wanted $_[0]\->$_[1] at $_[2]:$_[3]"
};
- # croaks 'You really wanted Pineapple->new at blurp.pm:13'
- my $z = new Pineapple 'fresh';
+ my $z = new Pineapple 'fresh'; # croaks 'You really wanted...'
}
}
- try { ... }; # warns
+ try { ... }; # warns if try() hasn't been declared in this package
- no indirect ':fatal'; # or 'FATAL', or ':Fatal' ...
+ no indirect 'fatal'; # or ':fatal', 'FATAL', ':Fatal' ...
if (defied $foo) { ... } # croaks, note the typo
- # Globally enabled from the command-line
+Global uses :
+
+ # Globally enable the pragma from the command-line
perl -M-indirect=global -e 'my $x = new Banana;' # warns
- # Or globally enabled each time perl is executed
- export PERL5OPT="-M-indirect=global"
- perl -e 'my $y = new Coconut;' # warns
+ # Globally enforce the pragma each time perl is executed
+ export PERL5OPT="-M-indirect=global,fatal"
+ perl -e 'my $y = new Coconut;' # croaks
=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.
+When enabled, this pragma warns about indirect method calls that are present in your code.
-This syntax is now considered harmful, since its parsing has many quirks and its use is error prone (when C<swoosh> is not 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.
+The indirect syntax is now considered harmful, since its parsing has many quirks and its use is error prone : when the subroutine C<foo> has not been declared in the current package, C<foo $x> actually compiles to C<< $x->foo >>, and C<< foo { key => 1 } >> to C<< 'key'->foo(1) >>.
+Please refer to the L</REFERENCES> section for a more complete list of reasons for avoiding this construct.
-
It currently does not warn for core functions (C<print>, C<say>, C<exec> or C<system>).
+
This pragma 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.
=head1 METHODS
-=head2 C<< unimport [ 'global', hook => $hook | 'fatal' ] >>
+=head2 C<unimport>
+
+ no indirect;
+ no indirect 'fatal';
+ no indirect hook => sub { my ($obj, $name, $file, $line) = @_; ... };
+ no indirect 'global';
+ no indirect 'global, 'fatal';
+ no indirect 'global', hook => sub { ... };
Magically called when C<no indirect @opts> is encountered.
Turns the module on.
=item *
-If it is a string that matches C</^:?fatal$/i>, the compilation will croak on the first indirect syntax met.
+If it is a string that matches C</^:?fatal$/i>, the compilation will croak when the first indirect method call is found.
+
+This option is mutually exclusive with the C<'hook'> option.
=item *
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<'{'>.
+This option is mutually exclusive with the C<'fatal'> option.
+
=item *
-If none of C<fatal> and C<hook> are specified, a warning will be emitted for each indirect construct.
+If none of C<fatal> and C<hook> are specified, a warning will be emitted for each indirect method call.
=item *
=cut
+sub _no_hook_and_fatal {
+ require Carp;
+ Carp::croak("The 'fatal' and 'hook' options are mutually exclusive");
+}
+
sub unimport {
shift;
- my $hook;
- my $global;
+ my ($global, $fatal, $hook);
+
while (@_) {
my $arg = shift;
if ($arg eq 'hook') {
- last if $hook;
+ _no_hook_and_fatal() if $fatal;
$hook = shift;
} elsif ($arg =~ /^:?fatal$/i) {
- last if $hook;
- $hook = sub { die msg(@_) };
+ _no_hook_and_fatal() if defined $hook;
+ $fatal = 1;
} elsif ($arg =~ /^:?global$/i) {
$global = 1;
}
}
- $hook = sub { warn msg(@_) } unless defined $hook;
+
+ unless (defined $hook) {
+ $hook = $fatal ? sub { die msg(@_) } : sub { warn msg(@_) };
+ }
$^H |= 0x00020000;
if ($global) {
=head2 C<import>
+ use indirect;
+
Magically called at each C<use indirect>. Turns the module off.
As explained in L</unimport>'s description, an C<use indirect> statement will lexically override a global policy previously installed by C<no indirect 'global', ...> (if there's one).
=head1 FUNCTIONS
-=head2 C<msg $object, $method, $file, $line>
+=head2 C<msg>
+
+ my $msg = msg($object, $method, $file, $line);
-Returns the default error message generated by C<indirect> when an invalid construct is reported.
+Returns the default error message that C<indirect> generates when an indirect method call is reported.
=cut
=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.
+The default warning/exception message thrown when an indirect method 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.
+The default warning/exception message thrown when an indirect method call on a block is found.
=head1 ENVIRONMENT
The implementation was tweaked to work around several limitations of vanilla C<perl> pragmas : it's thread safe, and does not suffer from a C<perl 5.8.x-5.10.0> bug that causes all pragmas to propagate into C<require>d scopes.
-Before C<perl> 5.12, C<meth $obj> (no semicolon) at the end of a file is not seen as an indirect object syntax, although it is as soon as there is another token before the end (as in C<meth $obj;> or C<meth $obj 1>).
+Before C<perl> 5.12, C<meth $obj> (no semicolon) at the end of a file is not seen as an indirect method call, although it is as soon as there is another token before the end (as in C<meth $obj;> or C<meth $obj 1>).
If you use C<perl> 5.12 or greater, those constructs are correctly reported.
With 5.8 perls, the pragma does not propagate into C<eval STRING>.
The search for indirect method calls happens before constant folding.
Hence C<my $x = new Class if 0> will be caught.
+=head1 REFERENCES
+
+Numerous articles have been written about the quirks of the indirect object construct :
+
+=over 4
+
+=item *
+
+L<http://markmail.org/message/o7d5sxnydya7bwvv> : B<Far More Than Everything You've Ever Wanted to Know about the Indirect Object syntax>, Tom Christiansen, 1998-01-28.
+
+This historical post to the C<perl5-porters> mailing list raised awareness about the perils of this syntax.
+
+=item *
+
+L<http://www.shadowcat.co.uk/blog/matt-s-trout/indirect-but-still-fatal> : B<Indirect but still fatal>, Matt S. Trout, 2009-07-29.
+
+In this blog post, the author gives an example of an undesirable indirect method call on a block that causes a particularly bewildering error.
+
+=back
+
=head1 DEPENDENCIES
L<perl> 5.8.1.
A C compiler.
This module may happen to build with a C++ compiler as well, but don't rely on it, as no guarantee is made in this regard.
-L<XSLoader> (standard since perl 5.006).
+L<Carp> (standard since perl 5), L<XSLoader> (since perl 5.6.0).
=head1 AUTHOR
perldoc indirect
-Tests code coverage report is available at L<http://www.profvince.com/perl/cover/indirect>.
-
=head1 ACKNOWLEDGEMENTS
Bram, for motivation and advices.
=head1 COPYRIGHT & LICENSE
-Copyright 2008,2009,2010,2011 Vincent Pit, all rights reserved.
+Copyright 2008,2009,2010,2011,2012,2013,2014,2015,2016,2017 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