NAME

       Rinci::FAQ - FAQ on Rinci

VERSION

       This document describes version 1.1.102 of Rinci::FAQ (from Perl distribution Rinci),
       released on 2022-04-22.

FAQ

   Rinci::function
       •   Why do you make enveloped result an array instead of hash?

           For example, a hash-based enveloped result can be something like:

            {status=>200, message=>"OK", result=>42, meta1=>..., meta2=>...}

           This has the benefit of a single container, but I picked array because of the brevity
           for simple cases (which are the majority), e.g.:

            [200]        # versus {status=>200}
            [200, "OK"]  # versus {status=>200, message=>"OK"}

           When handling enveloped result, the array version is also shorter:

            if ($res->[0] == 200) { ... }
            # versus: if ($res->{status} == 200) { ... }

            print "Error $res->[0] - $res->[1]";
            # versus: print "Error $res->{status} - $res->{message}";

           The hash version is more obvious for first-time reader, but after just some amount of
           time, "$res->[0]", "$res->[1]" will become obvious if you use it consistently.

           As a bonus, arrays are faster and more space-efficient than hashes.

       •   How do you indicate transient/temporary vs permanent errors?

           Some protocols, like SMTP or POP, defines 4xx codes as temporary errors and 5xx as
           permanent ones. This gives clue to clients whether to retry or not. HTTP, which Rinci
           is modelled after, does not provide such distinction to its status codes. However,
           Rinci defines a "perm_err" result metadata that can be used for such purpose, e.g.:

            [500, "Can't submit mail, we are being blocked by RBL", undef,
             {perm_err=>0}]

            [500, "Can't submit mail, destination address does not exist", undef,
             {perm_err=>1}]

       •   How to handle binary data?

           To accept binary data, you can set one or more arguments as having the schema type
           "buf" (instead of "str"):

            args => {
                data => { schema => 'buf*', req=>1 },
            }

           To return binary data, you can set result's schema type to "buf", e.g.:

            result => { schema => 'buf*' }

           For handling binary data when writing Perl-based command-line applications, see
           Perinci::CmdLine::Manual::Examples.

       •   How to accept partial data?

           First, set an argument property "partial" to true to signify that this argument accept
           partial value. You can then call with special arguments "-arg_len", "-arg_part_start",
           "-arg_part_len". See Rinci::function for more details.  Riap::HTTP can also do this
           via HTTP Content-Range.

       •   How to accept streaming input?

           Many program environments (like in Unix) have the concept of standard input.  Rinci
           provides a thin abstraction over this. You can set the argument property "stream" to
           true. This way, in most implementation like in Perl, your function will receive the
           argument value as filehandle which it can then read from. See "partial" property in
           "args" function metadata property in Rinci::function for an example.

           Your function can also read from standard input directly, but this means you cannot
           use conveniences like the "cmdline_src", where the command-line framework can supply
           an argument value for you from various sources including standard input and/or files.

       •   How to produce streaming output?

           Many program environments (like in Unix) have the concept of standard output. To
           produce output stream, you can set result metadata property "stream" to true.  And
           then in the result you can put a filehandle or an object that responds to
           getline/getitem methods.

       •   What is the difference between accepting partial data and streaming input?

           If a function accepts partial data, to send a large data without taking up too much
           memory, a caller needs to break the data into several parts and call the function
           several times, each with a different part.

           If a function accepts a stream input, to send a large data a caller can send a
           filehandle/iterator object from which the function can read the data iteratively.

           Stream input is easier and simpler for the function writer to write. A caller also
           only needs to call the function once instead of multiple times. However, there is no
           resume capability.

           On the other hand, partial input data is easier to implement with Riap::HTTP, as it
           maps rather closely to HTTP Content-Range.

           If you are uploading a large data over a network to a function, partial input data is
           preferred because of its ease to work with HTTP and its resume ability.

           However, if input is really a stream (i.e. unknown/infinite length), then streaming
           input is the option to use.

       •   What is the difference between returning partial result and streaming output?

           If a function can return partial result, to retrieve a large result from a function a
           caller can calls several times and each time request to retrieve parts of result.

           If a function returns output stream, a caller can then retrieve data from the stream
           iteratively.

           Output stream is easier to handle by the caller. The caller also only needs to call
           once instead of multiple times. However, there is no resume capability.

           On the other hand, partial result is easier to implement with Riap::HTTP, as it maps
           rather closely to HTTP Content-Range.

           If you are retrieving a large data over a network from a function, partial result is
           preferred because of its ease to work with HTTP

HOMEPAGE

       Please visit the project's homepage at <https://metacpan.org/release/Rinci>.

SOURCE

       Source repository is at <https://github.com/perlancar/perl-Rinci>.

AUTHOR

       perlancar <perlancar@cpan.org>

CONTRIBUTING

       To contribute, you can send patches by email/via RT, or send pull requests on GitHub.

       Most of the time, you don't need to build the distribution yourself. You can simply modify
       the code, then test via:

        % prove -l

       If you want to build the distribution (e.g. to try to install it locally on your system),
       you can install Dist::Zilla, Dist::Zilla::PluginBundle::Author::PERLANCAR, and sometimes
       one or two other Dist::Zilla plugin and/or Pod::Weaver::Plugin. Any additional steps
       required beyond that are considered a bug and can be reported to me.

COPYRIGHT AND LICENSE

       This software is copyright (c) 2022, 2021, 2020, 2019, 2018, 2017, 2016, 2015, 2014, 2013,
       2012 by perlancar <perlancar@cpan.org>.

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

BUGS

       Please report any bugs or feature requests on the bugtracker website
       <https://rt.cpan.org/Public/Dist/Display.html?Name=Rinci>

       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.