README

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 => {
          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" is defined in 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.

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

AUTHORS

    Steffen Mueller <smueller@cpan.org>
    chocolateboy <chocolate@cpan.org>

COPYRIGHT AND LICENSE

    Copyright (C) 2008-2020 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.