Class::XSAccessor(3pm)         User Contributed Perl Documentation         Class::XSAccessor(3pm)



NAME
       Class::XSAccessor - Generate fast XS accessors without runtime compilation

SYNOPSIS
         package MyClass;
         use Class::XSAccessor
           replace     => 1,   # Replace existing methods (if any)
           constructor => 'new',
           getters     => {
             get_foo => 'foo', # 'foo' is the hash key to access
             get_bar => 'bar',
           },
           setters => {
             set_foo => 'foo',
             set_bar => 'bar',
           },
           accessors => {
             foo => 'foo',
             bar => 'bar',
           },
           # "predicates" is an alias for "defined_predicates"
           defined_predicates => {
             defined_foo => 'foo',
             defined_bar => 'bar',
           },
           exists_predicates => {
             has_foo => 'foo',
             has_bar => 'bar',
           },
           lvalue_accessors => { # see below
             baz => 'baz', # ...
           },
           true  => [ 'is_token', 'is_whitespace' ],
           false => [ 'significant' ];

         # The imported methods are implemented in fast XS.

         # normal class code here.

       As of version 1.05, some alternative syntax forms are available:

         package MyClass;

         # Options can be passed as a HASH reference, if preferred,
         # which can also help Perl::Tidy to format the statement correctly.
         use Class::XSAccessor {
            # If the name => key values are always identical,
            # the following shorthand can be used.
            accessors => [ 'foo', 'bar' ],
         };

DESCRIPTION
       Class::XSAccessor implements fast read, write and read/write accessors in XS.
       Additionally, it can provide predicates such as "has_foo()" for testing whether the
       attribute "foo" exists in the object (which is different from "is defined within the
       object").  It only works with objects that are implemented as ordinary hashes.
       Class::XSAccessor::Array implements the same interface for objects that use arrays for
       their internal representation.

       Since version 0.10, the module can also generate simple constructors (implemented in XS).
       Simply supply the "constructor => 'constructor_name'" option or the "constructors =>
       ['new', 'create', 'spawn']" option.  These constructors do the equivalent of the following
       Perl code:

         sub new {
           my $class = shift;
           return bless { @_ }, ref($class)||$class;
         }

       That means they can be called on objects and classes but will not clone objects entirely.
       Parameters to "new()" are added to the object.

       The XS accessor methods are between 3 and 4 times faster than typical pure-Perl accessors
       in some simple benchmarking.  The lower factor applies to the potentially slightly obscure
       "sub set_foo_pp {$_[0]->{foo} = $_[1]}", so if you usually write clear code, a factor of
       3.5 speed-up is a good estimate.  If in doubt, do your own benchmarking!

       The method names may be fully qualified. The example in the synopsis could have been
       written as "MyClass::get_foo" instead of "get_foo". This way, methods can be installed in
       classes other than the current class. See also: the "class" option below.

       By default, the setters return the new value that was set, and the accessors (mutators) do
       the same. This behaviour can be changed with the "chained" option - see below. The
       predicates return a boolean.

       Since version 1.01, "Class::XSAccessor" can generate extremely simple methods which just
       return true or false (and always do so). If that seems like a really superfluous thing to
       you, then consider a large class hierarchy with interfaces such as PPI. These methods are
       provided by the "true" and "false" options - see the synopsis.

       "defined_predicates" check whether a given object attribute is defined.  "predicates" is
       an alias for "defined_predicates" for compatibility with older versions of
       "Class::XSAccessor". "exists_predicates" checks whether the given attribute exists in the
       object using "exists".

OPTIONS
       In addition to specifying the types and names of accessors, additional options can be
       supplied which modify behaviour. The options are specified as key/value pairs in the same
       manner as the accessor declaration. For example:

         use Class::XSAccessor
           getters => {
             get_foo => 'foo',
           },
           replace => 1;

       The list of available options is:

   replace
       Set this to a true value to prevent "Class::XSAccessor" from complaining about replacing
       existing subroutines.

   chained
       Set this to a true value to change the return value of setters and mutators (when called
       with an argument).  If "chained" is enabled, the setters and accessors/mutators will
       return the object. Mutators called without an argument still return the value of the
       associated attribute.

       As with the other options, "chained" affects all methods generated in the same "use
       Class::XSAccessor ..." statement.

   class
       By default, the accessors are generated in the calling class. The the "class" option
       allows the target class to be specified.

LVALUES
       Support for lvalue accessors via the keyword "lvalue_accessors" was added in version 1.08.
       At this point, THEY ARE CONSIDERED HIGHLY EXPERIMENTAL. Furthermore, their performance
       hasn't been benchmarked yet.

       The following example demonstrates an lvalue accessor:

         package Address;
         use Class::XSAccessor
           constructor => 'new',
           lvalue_accessors => { zip_code => 'zip' };

         package main;
         my $address = Address->new(zip => 2);
         print $address->zip_code, "\n"; # prints 2
         $address->zip_code = 76135; # <--- This is it!
         print $address->zip_code, "\n"; # prints 76135

CAVEATS
       Probably won't work for objects based on tied hashes. But that's a strange thing to do
       anyway.

       Scary code exploiting strange XS features.

       If you think writing an accessor in XS should be a laughably simple exercise, then please
       contemplate how you could instantiate a new XS accessor for a new hash key that's only
       known at run-time. Note that compiling C code at run-time a la Inline::C is a no go.

       Threading. With version 1.00, a memory leak has been fixed. Previously, a small amount of
       memory would leak if "Class::XSAccessor"-based classes were loaded in a subthread without
       having been loaded in the "main" thread. If the subthread then terminated, a hash key and
       an int per associated method used to be lost. Note that this mattered only if classes were
       only loaded in a sort of throw-away thread.

       In the new implementation, as of 1.00, the memory will still not be released, in the same
       situation, but it will be recycled when the same class, or a similar class, is loaded
       again in any thread.

SEE ALSO
       ·   Class::XSAccessor::Array

       ·   AutoXS

AUTHOR
       Steffen Mueller <smueller AT cpan.org>

       chocolateboy <chocolate AT cpan.org>

COPYRIGHT AND LICENSE
       Copyright (C) 2008, 2009, 2010, 2011, 2012, 2013 by Steffen Mueller

       This library is free software; you can redistribute it and/or modify it under the same
       terms as Perl itself, either Perl version 5.8 or, at your option, any later version of
       Perl 5 you may have available.



perl v5.20.2                                2013-11-22                     Class::XSAccessor(3pm)