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 -lIf 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.