NAME

       Eval::TypeTiny - utility to evaluate a string of Perl code in a clean environment

STATUS

       This module is covered by the Type-Tiny stability policy.

DESCRIPTION

       This module is used by Type::Tiny to compile coderefs from strings of Perl code, and
       hashrefs of variables to close over.

   Functions
       By default this module exports one function, which works much like the similarly named
       function from Eval::Closure:

       "eval_closure(source => $source, environment => \%env, %opt)"

       Other functions can be imported on request:

       "set_subname( $fully_qualified_name, $coderef )"
           Works like the similarly named function from Sub::Util, but will fallback to doing
           nothing if neither Sub::Util nor Sub::Name are available. Also will cowardly refuse
           the set the name of a coderef a second time if it's already named it.

       "type_to_coderef( $type, %options )"
           Turns a Type::Tiny object into a coderef, suitable for installing into a symbol table
           to create a function like "ArrayRef" or "Int".  (Actually should work for any object
           which provides "is_parameterizable", "parameterize", and "qualified_name" methods,
           such as Type::Coercion.)

           $options{post_method} can be a string of Perl indicating a method to call on the type
           constraint before returning it. For example '->moose_type'.

           $options{description} can be a description of the coderef which may be shown in stack
           traces, etc.

           The coderef will be named using "set_subname" unless $options{anonymous} is true.

           If $type is undef, then it is assumed that the type constraint hasn't been defined yet
           but will later, yet you still want a function now.  $options{type_library} and
           $options{type_name} will be used to find the type constraint when the function gets
           called.

   Constants
       The following constants may be exported, but are not by default.

       "HAS_LEXICAL_SUBS"
           Boolean indicating whether Eval::TypeTiny has support for lexical subs.  (This feature
           requires Perl 5.18.)

       "ALIAS_IMPLEMENTATION"
           Returns a string indicating what implementation of "alias => 1" is being used.
           Eval::TypeTiny will automatically choose the best implementation.  This constant can
           be matched against the "IMPLEMENTAION_*" constants.

       "IMPLEMENTATION_NATIVE"
           If "ALIAS_IMPLEMENTATION eq IMPLEMENTATION_NATIVE" then Eval::TypeTiny is currently
           using Perl 5.22's native alias feature. This requires Perl 5.22.

       "IMPLEMENTATION_DEVEL_LEXALIAS"
           If "ALIAS_IMPLEMENTATION eq IMPLEMENTATION_DEVEL_LEXALIAS" then Eval::TypeTiny is
           currently using Devel::LexAlias to provide aliases.

       "IMPLEMENTATION_PADWALKER"
           If "ALIAS_IMPLEMENTATION eq IMPLEMENTATION_PADWALKER" then Eval::TypeTiny is currently
           using PadWalker to provide aliases.

       "IMPLEMENTATION_TIE"
           If "ALIAS_IMPLEMENTATION eq IMPLEMENTATION_TIE" then Eval::TypeTiny is using the
           fallback implementation of aliases using "tie". This is the slowest implementation,
           and may cause problems in certain edge cases, like trying to alias already-tied
           variables, but it's the only way to implement "alias => 1" without a recent version of
           Perl or one of the two optional modules mentioned above.

       "NICE_PROTOTYPES"
           If this is true, then type_to_coderef will give parameterizable type constraints the
           slightly nicer prototype of "(;$)" instead of the default "(;@)". This allows
           constructs like:

              ArrayRef[Int] | HashRef[Int]

           ... to "just work".

EVALUATION ENVIRONMENT

       The evaluation is performed in the presence of strict, but the absence of warnings. (This
       is different to Eval::Closure which enables warnings for compiled closures.)

       The feature pragma is not active in the evaluation environment, so the following will not
       work:

          use feature qw(say);
          use Eval::TypeTiny qw(eval_closure);

          my $say_all = eval_closure(
             source => 'sub { say for @_ }',
          );
          $say_all->("Hello", "World");

       The feature pragma does not "carry over" into the stringy eval. It is of course possible
       to import pragmas into the evaluated string as part of the string itself:

          use Eval::TypeTiny qw(eval_closure);

          my $say_all = eval_closure(
             source => 'sub { use feature qw(say); say for @_ }',
          );
          $say_all->("Hello", "World");

BUGS

       Please report any bugs to <https://github.com/tobyink/p5-type-tiny/issues>.

SEE ALSO

       Eval::Closure, Error::TypeTiny::Compilation.

AUTHOR

       Toby Inkster <tobyink@cpan.org>.

COPYRIGHT AND LICENCE

       This software is copyright (c) 2013-2014, 2017-2023 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.