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PERLANCAR / Begin-Eval-Env-0.003 / README 

            

              
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NAME
    Begin::Eval::Env - Take code from environment variable(s), then eval
    them
VERSION
    This document describes version 0.003 of Begin::Eval::Env (from Perl
    distribution Begin-Eval-Env), released on 2022-02-05.
SYNOPSIS
    On the command-line:
     % PERL_BEGIN_EVAL_ENV='use Data::Dump; dd \%INC' perl -MBegin::Eval::Env `which some-perl-script.pl` ...
     % PERL_BEGIN_EVAL_ENV='use Data::Dump; dd \%INC' PERL5OPT=-MBegin::Eval::Env some-perl-script.pl ...
    Customize the environment variables:
     % perl -MBegin::Eval::Env=ENVNAME1,ENVNAME2 `which some-perl-script.pl` ...
     % PERL5OPT=-MBegin::Eval::Env=ENVNAME1,ENVNAME2 some-perl-script.pl ...
DESCRIPTION
    This module allows you to evaluate code(s) in environment variable(s),
    basically for convenience in one-liners. If name(s) of environment
    variables are not specified, "PERL_BEGIN_EVAL_ENV" is the default.
    Caveat: to run the code(s) in BEGIN block, you have to load the module
    in the BEGIN block also, e.g. via "use" not "require".
    The purpose of Begin::Eval::* and End::Eval::* modules is to allow you
    to evaluate some extra Perl code in addition to running your
    application, respectively at the beginning and at the end. The code can
    be supplied via one of these means: first command-line argument,
    environment variable(s). Previously there are Begin::Eval and End::Eval
    modules that accept code from import arguments, but the limited syntax
    provided by perl's "-M" switch diminishes the usefulness of the modules.
    Thus the modules are removed from CPAN.
    Use cases include:
    *   printing \%INC at the start of your program run
         % perl -MBegin::Eval::FirstArg /path/to/your-script.pl 'print "$_\n" for sort keys %INC' script-arg1 ...
         % PERL_BEGIN_EVAL_END='print "$_\n" for sort keys %INC' perl -MBegin::Eval::Env /path/to/your-script.pl script-arg1 ...
        To know which modules are loaded before your program runs.
    *   printing \%INC at the beginning of your program run
        To know all the modules that are loaded during your program run.
    *   loading a module at the beginning of your program, with some
        initialization
    Alternatives to using these modules include using "do":
     % perl -E 'your-extra-code-before-running-program; do "/path/to/your/script.pl"; your-extra-code-after-running-program'
ENVIRONMENT
  DEBUG
    Bool. Can be turned on to print the code to STDOUT before eval-ing it.
  PERL_BEGIN_EVAL_ENV
HOMEPAGE
    Please visit the project's homepage at
    <https://metacpan.org/release/Begin-Eval-Env>.
SOURCE
    Source repository is at
    <https://github.com/perlancar/perl-Begin-Eval-Env>.
SEE ALSO
    Other "Begin::Eval::*" modules, like Begin::Eval::FirstArg.
    "End::Eval::*" modules.
    Other Begin::* modules.
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 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=Begin-Eval-Env>
    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.