NAME

Mojo::Promisify - Convert callback code to promise based code

SYNOPSIS

use Mojo::Promisify qw(promisify_call promisify_patch);
use Some::NonBlockingClass;

# Create an object from a callback based class
my $nb_obj = Some::NonBlockingClass->new;

# Call a callback based method, but return a Mojo::Promise
promisify_call($nb_obj => get_stuff_by_id => 42)
  ->then(sub { print @_ })
  ->catch(sub { warn $_[0] });

# Add a method that wraps around the callback based method and return a
# Mojo::Promise.
promisify_patch "Some::NonBlockingClass" => "get_stuff_by_id";

# The added method has the "_p" suffix
$nb_obj->get_stuff_by_id_p(42)->then(sub { print @_ });

DESCRIPTION

Mojo::Promisify is a utility module that can upgrade your legacy callback based API to a Mojo::Promise based API.

It might not be the most efficient way to run your code, but it will allow you to easily add methods that will return promises.

This module only works with methods that passes on $err as the first argument to the callback, like this:

sub get_stuff_by_id {
  my ($self, $id, $cb) = @_;

  my $err = "Some error";
  my $res = undef;
  Mojo::IOLoop->next_tick(sub { $self->$cb($err, $res) });

  return $self;
}

The wrapped method can however pass on as many arguments as it wants after the $err and all will be passed on to the fulfillment callback in the promise. The promise will be rejected if $err has a value.

Note that this module is currently EXPERIMENTAL, but it will most probably not change much.

FUNCTIONS

promisify

$code = promisify($obj => $method);
$promise = $code->(@args);

Returns a closure that wraps around a given $method for the $obj and returns a promise. @args are the same arguments you would normally give to the $method, but without the callback at the end.

promisify_call

$promise = promisify_call($obj => $method, @args);

This function is the same as:

$promise = promisify($obj => $method)->(@args);

promisify_patch

promisify_patch $class, @methods;

Used to patch a class with new promise based methods. The methods that are patched in will have the "_p" suffix added.

Note that this function will replace existing methods!

AUTHOR

Jan Henning Thorsen

COPYRIGHT AND LICENSE

Copyright (C) 2019, Jan Henning Thorsen.

This program is free software, you can redistribute it and/or modify it under the terms of the Artistic License version 2.0.

SEE ALSO

Mojo::Promise