A Perl 6 method trait to turn indivdual get/set subroutines into a single read/write object attribute.
This module was initially designed to reduce the boiler plate code in a native library binding that became something like:
class Shout is repr('CPointer') {
sub shout_set_host(Shout, Str) returns int32 is native('libshout') { * }
sub shout_get_host(Shout) returns Str is native('libshout') { * }
method host() is rw {
Proxy.new(
FETCH => sub ($) {
shout_get_host(self);
},
STORE => sub ($, $host is copy ) {
explicitly-manage($host);
shout_set_host(self, $host);
}
);
}
...
}
That is the library API provides a sort of "object oriented" mechanism to set and get attributes on an opaque object instance that was returned by another "constructor" function. Because the object is an opaque CPointer it can only have subroutines and methods and not private data or attributes. The intent of the code is to provide fake "attributes" with rw methods (which is similar to how public rw attributes are provided.)
The above code will be reduced with the use of AccessorFacade to:
class Shout is repr('CPointer') {
sub shout_set_host(Shout, Str) returns int32 is native('libshout') { * }
sub shout_get_host(Shout) returns Str is native('libshout') { * }
method host() is rw is accessor-facade(&shout_set_host, &shout_get_host) { }
...
}
(The call to explicitly manage is omitted for simplicity but how this is achieved is described in the documentation.) Libshout has a significant number of these get/set pairs so there is a reduction of typing, copy and paste and hopefully programmer error.
Whilst this was designed primarily to work with a fixed native API, it is possible that it could be used to provide an OO facade to a plain perl procedural library. The only requirement that there is a getter subroutine that accepts an object as its first argument and returns the attribute value and a setter subroutine that accepts the object and the value to be set (it may return a value to indicate success - how this is handled is descibed in the documentation.)
Assuming you have a working perl6 installation you should be able to install this with ufo :
ufo
make test
make install
ufo can be installed with panda for rakudo:
panda install ufo
Or you can install directly with "panda":
# From the source directory
panda install .
# Remote installation
panda install AccessorFacade
Other install mechanisms may be become available in the future.
This should be considered experimental software until such time that Perl 6 reaches an official release. However suggestions/patches are welcomed via github at:
https://github.com/jonathanstowe/AccessorFacade
It may use features and behaviour of Perl 6 that aren't present in even slightly older builds (and which are anticipated to be in a release,) please check with a new build before reporting a bug.
Please see the LICENCE file in the distribution
(C) Jonathan Stowe 2015