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

VERSION
    This document describes version 0.470 of Perinci::Sub::Util (from Perl
    distribution Perinci-Sub-Util), released on 2020-10-20.

SYNOPSIS
    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 die_err() and warn_err():

     use Perinci::Sub::Util qw(warn_err die_err);
     warn_err(403, "Forbidden");
     die_err(403, "Forbidden");

    Example for gen_modified_sub():

     use Perinci::Sub::Util qw(gen_modified_sub);

     $SPEC{list_users} = {
         v => 1.1,
         args => {
             search => {},
             is_suspended => {},
         },
     };
     sub list_users { ... }

     gen_modified_sub(
         output_name => 'list_suspended_users',
         base_name   => 'list_users',
         remove_args => ['is_suspended'],
         output_code => sub {
             list_users(@_, is_suspended=>1);
         },
     );

    Example for gen_curried_sub():

     use Perinci::Sub::Util qw(gen_curried_sub);

     $SPEC{list_users} = {
         v => 1.1,
         args => {
             search => {},
             is_suspended => {},
         },
     };
     sub list_users { ... }

     # simpler/shorter than gen_modified_sub, but can be used for currying only
     gen_curried_sub('list_users', {is_suspended=>1}, 'list_suspended_users');

FUNCTIONS
  gen_curried_sub
    Usage:

     gen_curried_sub( [ \%optional_named_args ] , $base_name, $output_name) -> any

    Generate curried subroutine (and its metadata).

    This is a more convenient helper than "gen_modified_sub" if you want to
    create a new subroutine that has some of its arguments preset (so they
    no longer need to be present in the new metadata).

    For more general needs of modifying a subroutine (e.g. add some
    arguments, modify some arguments, etc) use "gen_modified_sub".

    This function is not exported by default, but exportable.

    Arguments ('*' denotes required arguments):

    *   $base_name* => *str*

        Subroutine name (either qualified or not).

        If not qualified with package name, will be searched in the caller's
        package. Rinci metadata will be searched in %SPEC package variable.

    *   $output_name* => *str*

        Where to install the modified sub.

        Subroutine will be put in the specified name. If the name is not
        qualified with package name, will use caller's package.

    *   set_args => *hash*

        Arguments to set.

    Return value: (any)

  gen_modified_sub
    Usage:

     gen_modified_sub(%args) -> [status, msg, payload, 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).

    This function is not exported by default, but exportable.

    Arguments ('*' denotes required arguments):

    *   add_args => *hash*

        Arguments to add.

    *   base_code => *code*

        Base subroutine code.

        If you specify this, you'll also need to specify "base_meta".

        Alternatively, you can specify "base_name" instead, to let this
        routine search the base subroutine from existing Perl package.

    *   base_meta => *hash*

        Base Rinci metadata.

    *   base_name => *str*

        Subroutine name (either qualified or not).

        If not qualified with package name, will be searched in the caller's
        package. Rinci metadata will be searched in %SPEC package variable.

        Alternatively, you can also specify "base_code" and "base_meta".

    *   description => *str*

        Description for the mod subroutine.

    *   install_sub => *bool* (default: 1)

    *   modify_args => *hash*

        Arguments to modify.

        For each argument you can specify a coderef. The coderef will
        receive the argument ($arg_spec) and is expected to modify the
        argument specification.

    *   modify_meta => *code*

        Specify code to modify metadata.

        Code will be called with arguments ($meta) where $meta is the cloned
        Rinci metadata.

    *   output_code => *code*

        Code for the modified sub.

        Alternatively you can use "wrap_code". If both are not specified,
        will use "base_code" (which will then be required) as the modified
        subroutine's code.

    *   output_name => *str*

        Where to install the modified sub.

        Subroutine will be put in the specified name. If the name is not
        qualified with package name, will use caller's package. If no
        "output_code" is specified, the base subroutine reference will be
        assigned here.

        Note that this argument is optional.

    *   remove_args => *array*

        List of arguments to remove.

    *   rename_args => *hash*

        Arguments to rename.

    *   replace_args => *hash*

        Arguments to add.

    *   summary => *str*

        Summary for the mod subroutine.

    *   wrap_code => *code*

        Wrapper to generate the modified sub.

        The modified sub will become:

         sub { wrap_code->(base_code, @_) }

        Alternatively you can use "output_code". If both are not specified,
        will use "base_code" (which will then be required) as the modified
        subroutine's code.

    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 (payload) is optional, the actual result. Fourth element (meta)
    is called result metadata and is optional, a hash that contains extra
    information.

    Return value: (hash)

  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
    Experimental.

    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.

    Examples:

     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.

  warn_err(...)
    This is a shortcut for:

     $res = err(...);
     warn "ERROR $res->[0]: $res->[1]";

  die_err(...)
    This is a shortcut for:

     $res = err(...);
     die "ERROR $res->[0]: $res->[1]";

FAQ
  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;

HOMEPAGE
    Please visit the project's homepage at
    <https://metacpan.org/release/Perinci-Sub-Util>.

SOURCE
    Source repository is at
    <https://github.com/perlancar/perl-Perinci-Sub-Util>.

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

    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.

SEE ALSO
    Perinci

AUTHOR
    perlancar <perlancar@cpan.org>

COPYRIGHT AND LICENSE
    This software is copyright (c) 2020, 2017, 2016, 2015, 2014 by
    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.

