NAME

       Sub::HandlesVia::CodeGenerator - looks at a Handler and generates a string of Perl code
       for it

DESCRIPTION

       This module is part of Sub::HandlesVia's internal API.  It is mostly of interest to people
       extending Sub::HandlesVia.

       Sub::HandlesVia toolkits create a code generator for each attribute they're dealing with,
       and use the code generator to generate Perl code for one or more delegated methods.

CONSTRUCTORS

   "new( %attributes )"
       Standard Moose-like constructor.

ATTRIBUTES

   "toolkit" Object
       The toolkit which made this code generator.

   "target" ClassName|RoleName
       The target package for generated methods.

   "sandboxing_package" ClassName|RoleName|Undef
       Package name to use as a sandbox; the default is usually fine.

   "attribute" Str|ArrayRef
       The attribute delegated to.

   "attribute_spec" HashRef
       Informational only.

   "is_method" Bool
       Indicates whether the generated code should be methods rather than functions.  This
       defaults to true, and false isn't really tested or well-defined.

   "env" HashRef
       Variables which need to be closed over when compiling coderefs.

   "isa" Maybe[TypeTiny]
       The type constraint for the attribute.

   "coerce" Bool
       Should the attribute coerce?

   "method_installer" CodeRef
       A coderef which can be called with $method_name and $coderef, will install the method.
       Note that it isn't passed the package to install into (which can be found in "target"), so
       that would need to be closed over.

   "generator_for_self" CodeRef
       A coderef which if called, generates a string like '$_[0]'.

       Has a sensible default.

       All the "generator_for_XXX" methods are called as methods, so have the code generator
       object as an invocant.

   "generator_for_slot" CodeRef
       A coderef which if called, generates a string like '$_[0]{attrname}'.

   "generator_for_get" CodeRef
       A coderef which if called, generates a string like '$_[0]->attrname'.

   "generator_for_set" CodeRef
       A coderef which if called with a parameter, generates a string like
       "\$_[0]->_set_attrname( $parameter )".

   "generator_for_simple_default" CodeRef
       A coderef which if called with a parameter, generates a string like 'undef' or 'q[]' or
       '{}'.

       The parameter is a handler object, which offers a "default_for_reset" attribute which
       might be able to provide a useful fallback.

   "generator_for_args" CodeRef
       A coderef which if called, generates a string like '@_[1..$#_]'.

       Has a sensible default.

   "generator_for_argc" CodeRef
       A coderef which if called, generates a string like '$#_'.

       Has a sensible default.

   "generator_for_argc" CodeRef
       A coderef which if called with a parameter, generates a string like "\$_[$parameter + 1]".

       Has a sensible default.

   "generator_for_currying" CodeRef
       A coderef which if called with a parameter, generates a string like
       "splice(\@_,1,0,$parameter);".

       Has a sensible default.

   "generator_for_usage_string" CodeRef
       The default is this coderef:

         sub {
           @_==3 or die;
           shift;
           my $method_name = shift;
           my $guts = shift;
           return "\$instance->$method_name($guts)";
         }

   "generator_for_type_assertion" CodeRef
       Called as a method and passed a hashref compilation environment, a type constraint, and a
       variable name. Generates code to assert that the variable value meets the type constraint,
       with coercion if appropriate.

   "generator_for_error" CodeRef
       Called as a method and passed a Perl string which is an expression evaluating to an error
       message. Generates code to throw the error.

   "generator_for_prelude" CodeRef
       By default is a coderef returning the empty string. Can be used to generate some
       additional statements which will be inserted near the top of the method being generated.
       (Typically after parameter checks but before doing anything serious.) This can be used to
       unlock a read-only attribute, for example.

   "get_is_lvalue" Bool
       Indicates wheter the code generated by "generator_for_get" will be suitable for used as an
       lvalue.

   "set_checks_isa" Bool
       Indicates wheter the code generated by "generator_for_set" will do type checks.

   "set_strictly" Bool
       Indicates wheter we want to ensure that the setter is always called, and we should not try
       to bypass it, even if we have an lvalue getter.

METHODS

       For each "generator_for_XXX" attribute, there's a corresponding "generate_XXX" method to
       actually call the coderef, possibly including additional processing.

   "generate_and_install_method( $method_name, $handler )"
       Given a handler and a method name, will generate a coderef for the handler and install it
       into the target package.

   "generate_coderef_for_handler( $method_name, $handler )"
       As above, but just returns the coderef rather than installs it.

   "install_method( $method_name, $coderef )"
       Installs a coderef into the target package with the given name.

BUGS

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

SEE ALSO

       Sub::HandlesVia.

AUTHOR

       Toby Inkster <tobyink@cpan.org>.

COPYRIGHT AND LICENCE

       This software is copyright (c) 2020, 2022 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.