NAME

Perinci::Sub::Wrapper - A multi-purpose subroutine wrapping framework

VERSION

version 0.23

SYNOPSIS

 use Perinci::Sub::Wrapper qw(wrap_sub);
 my $res = wrap_sub(sub => sub {die "test\n"}, meta=>{...});
 my ($wrapped, $meta) = ($res->[2]{sub}, $res->[2]{meta});
 $wrapped->(); # call the wrapped function

DESCRIPTION

Perinci::Sub::Wrapper is an extensible subroutine wrapping framework. It works by creating a single "large" wrapper function from a composite bits of code, instead of using multiple small wrappers (a la Python's decorator). The single-wrapper approach has the benefit of smaller function call overhead. You can still wrap multiple times if needed.

This module is used to enforce Rinci properties, e.g. args (by performing schema validation before calling the function), timeout (by doing function call inside an eval() and using alarm() to limit the execution), or retry (by wrapping function call inside a simple retry loop).

It can also be used to convert argument passing style, e.g. from args_as array to args_as hash, so you can call function using named arguments even though the function accepts positional arguments.

There are many other possible uses.

This module uses Log::Any for logging.

EXTENDING

The framework is simple and extensible. Please delve directly into the source code for now. Some notes:

The internal uses OO.

The main wrapper building mechanism is in the wrap() method.

For each Rinci property, it will call handle_NAME() wrapper handler method. The handlemeta_NAME() methods are called first, to determine order of processing. You can supply these methods either by subclassing the class or, more simply, monkeypatching the method in the Perinci::Sub::Wrapper package.

The wrapper handler method will be called with a hash argument, containing these keys: value (property value), new (this key will exist if convert argument of wrap() exists, to convert a property to a new value).

For properties that have name in the form of NAME1.NAME2.NAME3 (i.e., dotted) only the first part of the name will be used (i.e., handle_NAME1()).

METHODS

The OO interface is only used internally or when you want to extend the wrapper.

SEE ALSO

Perinci

FUNCTIONS

wrap_sub(%args) -> [status, msg, result, meta]

Wrap subroutine to do various things, like enforcing Rinci properties.

Will wrap subroutine and bless the generated wrapped subroutine (by default into 'Perinci::Sub::Wrapped') as a way of marking that the subroutine is a wrapped one.

Arguments ('*' denotes required arguments):

• compile => bool (default: 1)

  Whether to compile the generated wrapper.

  Can be set to 0 to not actually wrap but just return the generated wrapper source code.

• convert* => hash

  Properties to convert to new value.

  Not all properties can be converted, but these are a partial list of those that can: v (usually do not need to be specified when converting from 1.0 to 1.1, will be done automatically), argsas, resultnaked, default_lang.

• debug => bool (default: 0)

  Generate code with debugging.

  If turned on, will produce various debugging in the generated code. Currently what this does:

  • add more comments (e.g. for each property handler)

• meta* => hash

  The function metadata.

• normalize_schema => bool (default: 1)

  Whether to normalize schemas in metadata.

  By default, wrapper normalize Sah schemas in metadata, like in 'args' or 'result' property, for convenience so that it does not need to be normalized again prior to use. If you want to turn off this behaviour, set to false.

• remove_internal_properties => bool (default: 1)

  Whether to remove properties prefixed with _.

  By default, wrapper removes internal properties (properties which start with underscore) in the new metadata. Set this to false to keep them.

• sub* => code

  The code to wrap.

• trap => bool (default: 1)

  Whether to trap exception using an eval block.

  If set to true, will wrap call using an eval {} block and return 500 /undef if function dies. Note that if some other properties requires an eval block (like 'timeout') an eval block will be added regardless of this parameter.

Return value:

Returns an enveloped result (an array). First element (status) is an integer containing HTTP status code (200 means OK, 4xx caller error, 5xx function error). Second element (msg) is a string containing error message, or 'OK' if status is 200. Third element (result) is optional, the actual result. Fourth element (meta) is called result metadata and is optional, a hash that contains extra information.

AUTHOR

Steven Haryanto <stevenharyanto@gmail.com>

COPYRIGHT AND LICENSE

This software is copyright (c) 2012 by Steven Haryanto.

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

cpanm Perinci::Sub::Wrapper

perl -MCPAN -e shell
install Perinci::Sub::Wrapper