NAME

NAME
Syntax::Collector - collect a bundle of modules into one

SYNOPSIS
In lib/Example/ProjectX/Syntax.pm

package Example::ProjectX::Syntax;

use 5.010;
our $VERSION = 1;

use Syntax::Collector q/
use strict 0;
use warnings 0;
use feature 0 ':5.10';
use Scalar::Util 1.21 qw(blessed);
/;

1;
__END__

In projectx.pl:

#!/usr/bin/perl

use Example::ProjectX::Database;
use Example::ProjectX::Syntax 1;
# strict, warnings, feature ':5.10', etc are now enabled!

say "Welcome to ProjectX";

DESCRIPTION
Perl is such a flexible language that the language itself can be extended
from within. (Though much of the more interesting stuff needs XS hooks
like Devel::Declare.)

One problem with this is that it often requires a lot of declarations at
the top of your code, loading various syntax extensions. The syntax module
on CPAN addresses this somewhat by allowing you to load a bunch of
features in one line, provided each syntax feature implements the
necessary API:

use syntax qw/io maybe perform/;

However this introduces problems of its own. If we look at the code above,
it is non-obvious that it requires Syntax::Feature::Io,
Syntax::Feature::Maybe and Syntax::Feature::Perform, which makes it
difficult for automated tools such as Module::Install to automatically
calculate your code's dependencies.

Syntax::Collector to the rescue!

package Example::ProjectX::Syntax;
use 5.010;
use Syntax::Collector q/
use strict 0;
use warnings 0;
use feature 0 ':5.10';
use Scalar::Util 1.21 qw(blessed);
/;

When you `use Syntax::Collector`, you provide a list of modules to
"collect" into a single package (notice the `q/.../`). This list of
modules looks like a big string of Perl code that is going to be passed to
`eval`, but don't let that fool you - it is not.

Each line must conform to the following pattern:

(use|no) MODULENAME VERSION (OTHERSTUFF)? ;

(Actually hash comments, and blank lines are also allowed.) The semantics
of all that is pretty much what you'd expect, except that when MODULENAME
begins with "Syntax::Feature::" it's treated with some DWIMmery, and
`install` is called instead of `import`. Note that VERSION is required,
but if you don't care which version of a module you use, it's fine to set
VERSION to 0. (Yes, VERSION is even required for pragmata.)

Now, you ask... why stuff all that structured data into a string, and
parse it out again? Because to naive lexical analysis (e.g.
Module::Install) it really looks like a bunch of "use" lines, and not just
a single quoted string. This helps tools calculate the dependencies of
your collection; and thus the dependencies of other code that uses your
collection.

As well as providing an `import` method for your collection,
Syntax::Collector also provides a `modules` method, which can be called to
find out which modules a collection includes. Called in list context, it
returns a list. Called in scalar context, it returns a reference to a `{
module => version }` hash.

Exporting
Syntax::Collector will also make your class inherit from Exporter::Tiny so
that in addition to collecting up a bunch of features from other modules,
your syntax collection can also export its own functions.

package Example::ProjectX::Syntax;

use 5.010;
our $VERSION = 1;

use Syntax::Collector q/
use strict 0;
use warnings 0;
use feature 0 ':5.10';
use Scalar::Util 1.21 qw(blessed);
/;

our @EXPORT = qw( foo bar );

sub foo { ... }

1;
__END__

Import Options
Modules importing your syntax collection can suppress particular lines:

use Example::ProjectX::Syntax qw( -warnings );

Or provide alternative import options:

use Example::ProjectX::Syntax
'-Scalar::Util' => [qw/ blessed refaddr /];

See also Exporter::Tiny.

BUGS
Please report any bugs to
<http://rt.cpan.org/Dist/Display.html?Queue=Syntax-Collector>.

SEE ALSO
Exporter::Tiny.

AUTHOR
Toby Inkster <[email protected]>.

COPYRIGHT AND LICENCE
This software is copyright (c) 2012 by Toby Inkster.

This is free software; you can redistribute it and/or modify it under the
same terms as the Perl 5 programming language system itself.

DISCLAIMER OF WARRANTIES
THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.