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Eval::Closure(3)      User Contributed Perl Documentation     Eval::Closure(3)

NAME
       Eval::Closure - safely and cleanly create closures via string eval

VERSION
       version 0.08

SYNOPSIS
	 use Eval::Closure;

	 my $code = eval_closure(
	     source	 => 'sub { $foo++ }',
	     environment => {
		 '$foo' => \1,
	     },
	 );

	 warn $code->(); # 1
	 warn $code->(); # 2

	 my $code2 = eval_closure(
	     source => 'sub { $code->() }',
	 ); # dies, $code isn't in scope

DESCRIPTION
       String eval is often used for dynamic code generation. For instance,
       "Moose" uses it heavily, to generate inlined versions of accessors and
       constructors, which speeds code up at runtime by a significant amount.
       String eval is not without its issues however - it's difficult to
       control the scope it's used in (which determines which variables are in
       scope inside the eval), and it's easy to miss compilation errors, since
       eval catches them and sticks them in $@ instead.

       This module attempts to solve these problems. It provides an
       "eval_closure" function, which evals a string in a clean environment,
       other than a fixed list of specified variables. Compilation errors are
       rethrown automatically.

FUNCTIONS
   eval_closure(%args)
       This function provides the main functionality of this module. It is
       exported by default. It takes a hash of parameters, with these keys
       being valid:

       source
	   The string to be evaled. It should end by returning a code
	   reference. It can access any variable declared in the "environment"
	   parameter (and only those variables). It can be either a string, or
	   an arrayref of lines (which will be joined with newlines to produce
	   the string).

       environment
	   The environment to provide to the eval. This should be a hashref,
	   mapping variable names (including sigils) to references of the
	   appropriate type. For instance, a valid value for environment would
	   be "{ '@foo' => [] }" (which would allow the generated function to
	   use an array named @foo). Generally, this is used to allow the
	   generated function to access externally defined variables (so you
	   would pass in a reference to a variable that already exists).

       description
	   This lets you provide a bit more information in backtraces.
	   Normally, when a function that was generated through string eval is
	   called, that stack frame will show up as "(eval n)", where 'n' is a
	   sequential identifier for every string eval that has happened so
	   far in the program. Passing a "description" parameter lets you
	   override that to something more useful (for instance, Moose
	   overrides the description for accessors to something like "accessor
	   foo at MyClass.pm, line 123").

       line
	   This lets you override the particular line number that appears in
	   backtraces, much like the "description" option. The default is 1.

       terse_error
	   Normally, this function appends the source code that failed to
	   compile, and prepends some explanatory text. Setting this option to
	   true suppresses that behavior so you get only the compilation error
	   that Perl actually reported.

BUGS
       No known bugs.

       Please report any bugs through RT: email "bug-eval-closure at
       rt.cpan.org", or browse to
       <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Eval-Closure>.

SUPPORT
       You can find this documentation for this module with the perldoc
       command.

	   perldoc Eval::Closure

       You can also look for information at:

       ·   AnnoCPAN: Annotated CPAN documentation

	   <http://annocpan.org/dist/Eval-Closure>

       ·   CPAN Ratings

	   <http://cpanratings.perl.org/d/Eval-Closure>

       ·   RT: CPAN's request tracker

	   <http://rt.cpan.org/NoAuth/Bugs.html?Dist=Eval-Closure>

       ·   Search CPAN

	   <http://search.cpan.org/dist/Eval-Closure>

AUTHOR
       Jesse Luehrs <doy at tozt dot net>

       Based on code from Class::MOP::Method::Accessor, by Stevan Little and
       the Moose Cabal.

SEE ALSO
       ·   Class::MOP::Method::Accessor

	   This module is a factoring out of code that used to live here

COPYRIGHT AND LICENSE
       This software is copyright (c) 2012 by Jesse Luehrs.

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

perl v5.18.1			  2012-02-09		      Eval::Closure(3)
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