autovivification - Lexically disable autovivification.
VERSION
- Version 0.02
+ Version 0.10
SYNOPSIS
no autovivification;
METHODS
"unimport @opts"
- Magically called when "no autovivification" is encountered. Enables the
- features given in @opts, which can be :
+ Magically called when "no autovivification @opts" is encountered.
+ Enables the features given in @opts, which can be :
* 'fetch'
- Turn off autovivification for rvalue dereferencing expressions, such
- as "$value = $hashref->{key}[$idx]{$field}", "keys
- %{$hashref->{key}}" or "values %{$hashref->{key}}". When the
- expression would have autovivified, "undef" is returned for a plain
- fetch, while "keys" and "values" return 0 in scalar context and the
- empty list in list context.
+ Turns off autovivification for rvalue dereferencing expressions,
+ such as :
+
+ $value = $arrayref->[$idx]
+ $value = $hashref->{$key}
+ keys %$hashref
+ values %$hashref
+
+ Starting from perl 5.11, it also covers "keys" and "values" on array
+ references :
+
+ keys @$arrayref
+ values @$arrayref
+
+ When the expression would have autovivified, "undef" is returned for
+ a plain fetch, while "keys" and "values" return 0 in scalar context
+ and the empty list in list context.
* 'exists'
- Turn off autovivification for dereferencing expressions that are
- parts of an "exists", such as "exists
- $hashref->{key}[$idx]{$field}". '' is returned when the expression
- would have autovivified.
+ Turns off autovivification for dereferencing expressions that are
+ parts of an "exists", such as :
+
+ exists $arrayref->[$idx]
+ exists $hashref->{$key}
+
+ '' is returned when the expression would have autovivified.
* 'delete'
- Turn off autovivification for dereferencing expressions that are
- parts of a "delete", such as "delete $hashref->{key}[$idx]{$field}".
+ Turns off autovivification for dereferencing expressions that are
+ parts of a "delete", such as :
+
+ delete $arrayref->[$idx]
+ delete $hashref->{$key}
+
"undef" is returned when the expression would have autovivified.
* 'store'
- Turn off autovivification for lvalue dereferencing expressions, such
- as "$hashref->{key}[$idx]{$field} = $value". An exception is thrown
- if vivification is needed to store the value, which means that
- effectively you can only assign to levels that are already defined
- (in the example, this would require "$hashref->{key}[$idx]" to
- already be a hash reference).
+ Turns off autovivification for lvalue dereferencing expressions,
+ such as :
+
+ $arrayref->[$idx] = $value
+ $hashref->{$key} = $value
+ for ($arrayref->[$idx]) { ... }
+ for ($hashref->{$key}) { ... }
+ function($arrayref->[$idx])
+ function($hashref->{$key})
+
+ An exception is thrown if vivification is needed to store the value,
+ which means that effectively you can only assign to levels that are
+ already defined In the example, this would require $arrayref (resp.
+ $hashref) to already be an array (resp. hash) reference.
* 'warn'
- Emit a warning when an autovivification is avoided.
+ Emits a warning when an autovivification is avoided.
* 'strict'
- Throw an exception when an autovivification is avoided.
+ Throws an exception when an autovivification is avoided.
Each call to "unimport" adds the specified features to the ones already
in use in the current lexical scope.
- When @opts is empty, it defaults to "qw/fetch exists delete/".
+ When @opts is empty, it defaults to "qw<fetch exists delete>".
"import @opts"
- Magically called when "use autovivification" is encountered. Disables
- the features given in @opts, which can be the same as for "unimport".
+ Magically called when "use autovivification @opts" is encountered.
+ Disables the features given in @opts, which can be the same as for
+ "unimport".
Each call to "import" removes the specified features to the ones already
in use in the current lexical scope.
When @opts is empty, it defaults to restoring the original Perl
autovivification behaviour.
+CONSTANTS
+ "A_THREADSAFE"
+ True iff the module could have been built with thread-safety features
+ enabled. This constant only has a meaning with your perl is threaded ;
+ otherwise, it'll always be false.
+
+ "A_FORKSAFE"
+ True iff this module could have been built with fork-safety features
+ enabled. This will always be true except on Windows where it's false for
+ perl 5.10.0 and below .
+
+CAVEATS
+ The pragma doesn't apply when one dereferences the returned value of an
+ array or hash slice, as in "@array[$id]->{member}" or
+ @hash{$key}->{member}. This syntax is valid Perl, yet it's discouraged
+ as the slice is here useless since the dereferencing enforces scalar
+ context. If warnings are turned on, Perl will complain about one-element
+ slices.
+
DEPENDENCIES
- perl 5.8.
+ perl 5.8.3.
+
+ 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).
Matt S. Trout asked for it.
COPYRIGHT & LICENSE
- Copyright 2009 Vincent Pit, all rights reserved.
+ Copyright 2009,2010,2011 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 / autovivification.git / blobdiff