NAME
- indirect - Lexically warn about using the indirect object syntax.
+ indirect - Lexically warn about using the indirect method call syntax.
VERSION
- Version 0.18
+ Version 0.33
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
{
- no indirect hook => sub { die "You really wanted $_[0]\->$_[1] at $_[2]:$_[3]" };
- my $z = new Pineapple 'fresh'; # croaks 'You really wanted Pineapple->new at blurp.pm:13'
+ # lexically specify an hook called for each indirect construct
+ no indirect hook => sub {
+ die "You really wanted $_[0]\->$_[1] at $_[2]:$_[3]"
+ };
+ 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';
+ no indirect 'fatal'; # or ':fatal', 'FATAL', ':Fatal' ...
if (defied $foo) { ... } # croaks, note the typo
- # From the command-line
- perl -M-indirect -e 'my $x = new Banana;' # warns
+ Global uses :
- # Or each time perl is ran
- export PERL5OPT="-M-indirect"
- perl -e 'my $y = new Coconut;' # warns
+ # Globally enable the pragma from the command-line
+ perl -M-indirect=global -e 'my $x = new Banana;' # warns
-DESCRIPTION
- When enabled (or disabled as some may prefer to say, since you actually
- turn it on by calling "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 "swoosh" isn't defined, "swoosh $x"
- actually compiles to "$x->swoosh").
+ # Globally enforce the pragma each time perl is executed
+ export PERL5OPT="-M-indirect=global,fatal"
+ perl -e 'my $y = new Coconut;' # croaks
- It currently does not warn for core functions ("print", "say", "exec" or
- "system"). This may change in the future, or may be added as optional
- features that would be enabled by passing options to "unimport".
+DESCRIPTION
+ When enabled, this pragma warns about indirect method calls that are
+ present in your code.
+
+ The indirect syntax is now considered harmful, since its parsing has
+ many quirks and its use is error prone : when the subroutine "foo" has
+ not been declared in the current package, "foo $x" actually compiles to
+ "$x->foo", and "foo { key => 1 }" to "'key'->foo(1)". In
+ <http://www.shadowcat.co.uk/blog/matt-s-trout/indirect-but-still-fatal>,
+ Matt S. Trout gives an example of an undesirable indirect method call on
+ a block that can cause a particularly bewildering error.
+
+ This pragma currently does not warn for core functions ("print", "say",
+ "exec" or "system"). This may change in the future, or may be added as
+ optional features that would be enabled by passing options to
+ "unimport".
This module is not a source filter.
METHODS
- "unimport [ hook => $hook | ':fatal' ]"
+ "unimport"
+ no indirect;
+ no indirect 'fatal';
+ no indirect hook => sub { my ($obj, $name, $file, $line) = @_; ... };
+ no indirect 'global';
+ no indirect 'global, 'fatal';
+ no indirect 'global', hook => sub { ... };
+
Magically called when "no indirect @opts" is encountered. Turns the
module on. The policy to apply depends on what is first found in @opts :
- * If it's the string ':fatal', the compilation will croak on the first
- indirect syntax met.
+ * If it is a string that matches "/^:?fatal$/i", the compilation will
+ croak when the first indirect method call is found.
+
+ This option is mutually exclusive with the 'hook' option.
* If the key/value pair "hook => $hook" comes first, $hook will be
called for each error with a string representation of the object as
line number as $_[3]. If and only if the object is actually a block,
$_[0] is assured to start by '{'.
- * Otherwise, a warning will be emitted for each indirect construct.
+ This option is mutually exclusive with the 'fatal' option.
+
+ * If none of "fatal" and "hook" are specified, a warning will be
+ emitted for each indirect method call.
+
+ * If @opts contains a string that matches "/^:?global$/i", the pragma
+ will be globally enabled for all code compiled after the current "no
+ indirect" statement, except for code that is in the lexical scope of
+ "use indirect". This option may come indifferently before or after
+ the "fatal" or "hook" options, in the case they are also passed to
+ "unimport".
+
+ The global policy applied is the one resulting of the "fatal" or
+ "hook" options, thus defaults to a warning when none of those are
+ specified :
+
+ no indirect 'global'; # warn for any indirect call
+ no indirect qw<global fatal>; # die on any indirect call
+ no indirect 'global', hook => \&hook # custom global action
+
+ Note that if another policy is installed by a "no indirect"
+ statement further in the code, it will overrule the global policy :
+
+ no indirect 'global'; # warn globally
+ {
+ no indirect 'fatal'; # throw exceptions for this lexical scope
+ ...
+ require Some::Module; # the global policy will apply for the
+ # compilation phase of this module
+ }
"import"
+ use indirect;
+
Magically called at each "use indirect". Turns the module off.
+ As explained in "unimport"'s description, an "use indirect" statement
+ will lexically override a global policy previously installed by "no
+ indirect 'global', ..." (if there's one).
+
FUNCTIONS
- "msg $object, $method, $file, $line"
- Returns the default error message generated by "indirect" when an
- invalid construct is reported.
+ "msg"
+ my $msg = msg($object, $method, $file, $line);
+
+ Returns the default error message that "indirect" generates when an
+ indirect method call is reported.
CONSTANTS
"I_THREADSAFE"
True iff the module could have been built with thread-safety features
enabled.
+ "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 .
+
DIAGNOSTICS
"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.
"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.
ENVIRONMENT
"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 'indirect'
lexical hint will be set to true in the scope of use, the pragma itself
- won't do anything. This is useful for disabling "indirect" in production
- environments.
+ won't do anything. In this case, the pragma will always be considered to
+ be thread-safe, and as such "I_THREADSAFE" will be true. This is useful
+ for disabling "indirect" in production environments.
Note that clearing this variable after "indirect" was loaded has no
- effect. If you want to reenable the pragma later, you also need to
+ effect. If you want to re-enable the pragma later, you also need to
reload it by deleting the 'indirect.pm' entry from %INC.
CAVEATS
The implementation was tweaked to work around several limitations of
- vanilla "perl" pragmas : it's thread safe, and doesn't suffer from a
+ vanilla "perl" pragmas : it's thread safe, and does not suffer from a
"perl 5.8.x-5.10.0" bug that causes all pragmas to propagate into
"require"d scopes.
- "meth $obj" (no semicolon) at the end of a file won't be seen as an
- indirect object syntax, although it will as soon as there is another
- token before the end (as in "meth $obj;" or "meth $obj 1").
+ Before "perl" 5.12, "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 "meth $obj;" or "meth $obj 1"). If
+ you use "perl" 5.12 or greater, those constructs are correctly reported.
With 5.8 perls, the pragma does not propagate into "eval STRING". This
is due to a shortcoming in the way perl handles the hints hash, which is
addressed in perl 5.10.
+ Indirect constructs that appear in code "eval"'d during the global
+ destruction phase of a spawned thread or pseudo-fork (the processes used
+ internally for the "fork" emulation on Windows) are not reported.
+
The search for indirect method calls happens before constant folding.
Hence "my $x = new Class if 0" will be caught.
DEPENDENCIES
- perl 5.8.
+ 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.
- XSLoader (standard since perl 5.006).
+ Carp (standard since perl 5), XSLoader (since perl 5.6.0).
AUTHOR
Vincent Pit, "<perl at profvince.com>", <http://www.profvince.com>.
reporting issues.
COPYRIGHT & LICENSE
- Copyright 2008-2009 Vincent Pit, all rights reserved.
+ Copyright 2008,2009,2010,2011,2012,2013,2014 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