NAME Data::Sah::DefaultValue - Default-value rules for Data::Sah VERSION This document describes version 0.004 of Data::Sah::DefaultValue (from Perl distribution Data-Sah-DefaultValue), released on 2023-12-09. SYNOPSIS use Data::Sah::DefaultValue qw(gen_default_value_code); # a utility routine: gen_default_value_code my $dv = gen_default_value_code( default_value_rules => ['Perl::this_mod'], ); my $val = $c->(123); # unchanged, 123 my $val = $c->(undef); # becomes "Some::Module" DESCRIPTION This module generates code to set default value using value rules. A value rule is put in "Data::Sah::Value::$COMPILER::$TOPIC::$DESCRIPTION" module, for example: Data::Sah::Value::perl::Perl::this_mod contains the value "this module" (see App::ThisDist for more details on the meaning of "this module"). Basically, a value rule will provide an expression ("expr_value") that return some value. The module must contain "meta" subroutine which must return a hashref that has the following keys ("*" marks that the key is required): * v* => int (default: 1) Metadata specification version. From DefHash. Currently at 4. * summary => str From DefHash. The module must also contain "value" subroutine which must generate the code for default value. The subroutine must accept a hash of arguments ("*" indicates required arguments): The "value" subroutine must return a hashref with the following keys ("*" indicates required keys): * expr_value => str Expression in the target language that produces the value. * modules => hash A list of modules required by the expressions. VARIABLES $Log_Default_Value_Code => bool (default: from ENV or 0) If set to true, will log the generated default-value code (currently using Log::ger at trace level). To see the log message, e.g. to the screen, you can use something like: % TRACE=1 perl -MLog::ger::LevelFromEnv -MLog::ger::Output=Screen \ -MData::Sah::DefaultValue=gen_default_value_code -E'my $c = gen_default_value_code(...)' FUNCTIONS gen_default_value_code Usage: gen_default_value_code(%args) -> any Generate code to set default value. This is mostly for testing. Normally the default value rules will be used from Data::Sah via the "x.perl.default_value_rules" or "x.js.default_value_rules" or "x.default_value_rules" property. This function is not exported by default, but exportable. Arguments ('*' denotes required arguments): * default_value_rules => *array[str]* A specification of default-value rules to use (or avoid). This setting is used to specify which default-value rules to use (or avoid) in a flexible way. Each element is a string, in the form of either "NAME" to mean specifically include a rule, or "!NAME" to exclude a rule. To use the default-value rules R1 and R2: ['R1', 'R2'] * source => *bool* If set to true, will return coercer source code string instead of compiled code. Return value: (any) ENVIRONMENT LOG_SAH_DEFAULT_VALUE_CODE => bool Set default for $Log_Default_Value_Code. HOMEPAGE Please visit the project's homepage at <https://metacpan.org/release/Data-Sah-DefaultValue>. SOURCE Source repository is at <https://github.com/perlancar/perl-Data-Sah-DefaultValue>. SEE ALSO Data::Sah::DefaultValueCommon for detailed syntax of default-value rules (explicitly including/excluding rules etc). Data::Sah Data::Sah::DefaultValueJS App::SahUtils HISTORY 2021-11-28: Created modelled from Data::Sah::Coerce and Data::Sah::Filter to be able to express dynamic default value into schema. 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, Pod::Weaver::PluginBundle::Author::PERLANCAR, and sometimes one or two other Dist::Zilla- and/or Pod::Weaver plugins. Any additional steps required beyond that are considered a bug and can be reported to me. COPYRIGHT AND LICENSE This software is copyright (c) 2023, 2021 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=Data-Sah-DefaultValue > 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.