2 indirect - Lexically warn about using the indirect object syntax.
10 my $x = new Apple 1, 2, 3; # warns
13 my $y = new Pear; # ok
15 no indirect hook => sub { die "You really wanted $_[0]\->$_[1] at $_[2]:$_[3]" };
16 my $z = new Pineapple 'fresh'; # croaks 'You really wanted Pineapple->new at blurp.pm:13'
22 if (defied $foo) { ... } # croaks, note the typo
24 # From the command-line
25 perl -M-indirect -e 'my $x = new Banana;' # warns
27 # Or each time perl is ran
28 export PERL5OPT="-M-indirect"
29 perl -e 'my $y = new Coconut;' # warns
32 When enabled (or disabled as some may prefer to say, since you actually
33 turn it on by calling "no indirect"), this pragma warns about indirect
34 object syntax constructs that may have slipped into your code. This
35 syntax is now considered harmful, since its parsing has many quirks and
36 its use is error prone (when "swoosh" isn't defined, "swoosh $x"
37 actually compiles to "$x->swoosh").
39 It currently does not warn for core functions ("print", "say", "exec" or
40 "system"). This may change in the future, or may be added as optional
41 features that would be enabled by passing options to "unimport".
43 This module is not a source filter.
46 "unimport [ hook => $hook | ':fatal' ]"
47 Magically called when "no indirect @opts" is encountered. Turns the
48 module on. The policy to apply depends on what is first found in @opts :
50 * If it's the string ':fatal', the compilation will croak on the first
53 * If the key/value pair "hook => $hook" comes first, $hook will be
54 called for each error with a string representation of the object as
55 $_[0], the method name as $_[1], the current file as $_[2] and the
56 line number as $_[3]. If and only if the object is actually a block,
57 $_[0] is assured to start by '{'.
59 * Otherwise, a warning will be emitted for each indirect construct.
62 Magically called at each "use indirect". Turns the module off.
65 "msg $object, $method, $file, $line"
66 Returns the default error message generated by "indirect" when an
67 invalid construct is reported.
71 True iff the module could have been built with thread-safety features
75 True iff this module could have been built with fork-safety features
76 enabled. This will always be true except on Windows where it's false for
77 perl 5.10.0 and below .
80 "Indirect call of method "%s" on object "%s" at %s line %d."
81 The default warning/exception message thrown when an indirect call on an
84 "Indirect call of method "%s" on a block at %s line %d."
85 The default warning/exception message thrown when an indirect call on a
89 "PERL_INDIRECT_PM_DISABLE"
90 If this environment variable is set to true when the pragma is used for
91 the first time, the XS code won't be loaded and, although the 'indirect'
92 lexical hint will be set to true in the scope of use, the pragma itself
93 won't do anything. In this case, the pragma will always be considered to
94 be thread-safe, and as such "I_THREADSAFE" will be true. This is useful
95 for disabling "indirect" in production environments.
97 Note that clearing this variable after "indirect" was loaded has no
98 effect. If you want to reenable the pragma later, you also need to
99 reload it by deleting the 'indirect.pm' entry from %INC.
102 The implementation was tweaked to work around several limitations of
103 vanilla "perl" pragmas : it's thread safe, and doesn't suffer from a
104 "perl 5.8.x-5.10.0" bug that causes all pragmas to propagate into
107 "meth $obj" (no semicolon) at the end of a file won't be seen as an
108 indirect object syntax, although it will as soon as there is another
109 token before the end (as in "meth $obj;" or "meth $obj 1").
111 With 5.8 perls, the pragma does not propagate into "eval STRING". This
112 is due to a shortcoming in the way perl handles the hints hash, which is
113 addressed in perl 5.10.
115 The search for indirect method calls happens before constant folding.
116 Hence "my $x = new Class if 0" will be caught.
121 XSLoader (standard since perl 5.006).
124 Vincent Pit, "<perl at profvince.com>", <http://www.profvince.com>.
126 You can contact me by mail or on "irc.perl.org" (vincent).
129 Please report any bugs or feature requests to "bug-indirect at
130 rt.cpan.org", or through the web interface at
131 <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=indirect>. I will be
132 notified, and then you'll automatically be notified of progress on your
133 bug as I make changes.
136 You can find documentation for this module with the perldoc command.
140 Tests code coverage report is available at
141 <http://www.profvince.com/perl/cover/indirect>.
144 Bram, for motivation and advices.
146 Andrew Main and Florian Ragwitz, for testing on real-life code and
150 Copyright 2008-2009 Vincent Pit, all rights reserved.
152 This program is free software; you can redistribute it and/or modify it
153 under the same terms as Perl itself.