Steven Haryanto > Perinci-Sub-Util-0.38 > Perinci::Sub::Util



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Perinci::Sub::Util - Helper when writing functions


This document describes version 0.38 of Perinci::Sub::Util (from Perl distribution Perinci-Sub-Util), released on 2014-06-27.


Example for err() and caller():

 use Perinci::Sub::Util qw(err caller);

 sub foo {
     my %args = @_;
     my $res;

     my $caller = caller();

     $res = bar(...);
     return err($err, 500, "Can't foo") if $res->[0] != 200;

     [200, "OK"];

Example for gen_modified_sub()


caller([ $n ])

Just like Perl's builtin caller(), except that this one will ignore wrapper code in the call stack. You should use this if your code is potentially wrapped. See Perinci::Sub::Wrapper for more details.

err(...) => ARRAY


Generate an enveloped error response (see Rinci::function). Can accept arguments in an unordered fashion, by utilizing the fact that status codes are always integers, messages are strings, result metadata are hashes, and previous error responses are arrays. Error responses also seldom contain actual result. Status code defaults to 500, status message will default to "FUNC failed". This function will also fill the information in the logs result metadata.


 err();    # => [500, "FUNC failed", undef, {...}];
 err(404); # => [404, "FUNC failed", undef, {...}];
 err(404, "Not found"); # => [404, "Not found", ...]
 err("Not found", 404); # => [404, "Not found", ...]; # order doesn't matter
 err([404, "Prev error"]); # => [500, "FUNC failed", undef,
                           #     {logs=>[...], prev=>[404, "Prev error"]}]

Will put stack_trace in logs only if Carp::Always module is loaded.

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

Generate modified metadata (and subroutine) based on another.

Often you'll want to create another sub (and its metadata) based on another, but with some modifications, e.g. add/remove/rename some arguments, change summary, add/remove some properties, and so on.

Instead of cloning the Rinci metadata and modify it manually yourself, this routine provides some shortcuts.

You can specify base sub/metadata using base_name (string, subroutine name, either qualified or not) or base_code (coderef) + base_meta (hash).

Arguments ('*' denotes required arguments):

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.


What if I want to put result ($res->[2]) into my result with err()?

You can do something like this:

 my $err = err(...) if ERROR_CONDITION;
 $err->[2] = SOME_RESULT;
 return $err;


Perinci::Sub::Wrapper will generate wrapper that modifies caller() for the wrapped subroutine (like in Hook::LexWrap), so this module's caller() will not be needed in the future.




Please visit the project's homepage at


Source repository is at


Please report any bugs or feature requests on the bugtracker website

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.


Steven Haryanto <>


This software is copyright (c) 2014 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.

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