Christian Walde > Capture-Tiny-Extended-0.114 > Capture::Tiny::Extended

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Module Version: 0.114   Source  

NAME ^

Capture::Tiny::Extended - Capture STDOUT and STDERR from from Perl, XS or external programs (with some extras)

VERSION ^

version 0.114

SYNOPSIS ^

   use Capture::Tiny::Extended qw/capture tee capture_merged tee_merged/;
 
   # capture return values
 
   my ($stdout, $stderr, @return) = capture {
     # your code here
     return system( 'ls' );
   };
 
   ($merged, @return) = capture_merged {
     # your code here
     return system( 'ls' );
   };
 
   # or use explicit capture files
 
   ($stdout, $stderr, @return) = capture(
     sub { # your code here },
     { stdout => 'stdout.log' }
   );
 
   # or with sugar
 
   use Capture::Tiny::Extended qw/capture tee capture_merged tee_merged capture_files/;
 
   ($stdout, $stderr, @return) = capture {
     # your code here
   }
   capture_files (
     stdout => 'stdout.log',
     stderr => 'stderr.log',
   );

DESCRIPTION ^

Capture::Tiny::Extended is a fork of Capture::Tiny. It is functionally identical with the parent module, except for the differences documented in this POD. Please see the documentation of Capture::Tiny for details on standard usage.

Please note that this can be considered an experimental module in some respects. I am not as experienced with the subject matter (and in general) as David Golden and mostly implemented these features here because i needed them fast and did not have the time to spare to wait for them to get into Capture::Tiny. If you need capture functionality for mission-critical parts, consider whether Capture::Tiny might be enough for the job.

Of course I will however make all efforts to make this as stable and useful as possible by keeping it up-to-date (as my time permits) with changes and bugfixes applied to Capture::Tiny, as well as responding and addressing and change requests or bug reports for this module.

DIFFERENCES ^

Capturing Return Values

When executing code within a capture you sometimes want to also keep the return value, for example when capturing a system() call. In Capture::Tiny this has to be done like this:

   use Capture::Tiny 'capture';
 
   my $res;
   my ( $out, $err ) = capture {
     $res = system( 'ls' );
   };

Capture::Tiny::Extended automatically captures return values and returns them after the second return value (or first if you're using the merged functions).

   use Capture::Tiny::Extended 'capture';
 
   my ( $out, $err, $res ) = capture { system( 'ls' ) };

Teeing In Realtime

Sometimes you want to use Capture::Tiny to capture any and all output of an action and dump it into a log file, while also displaying it on the screen and then post-process the results later on (for example for sending status mails). The only way to do this with Capture::Tiny is code like this:

   use Capture::Tiny 'capture';
   use File::Slurp;
 
   my $res;
   my ( $out, $err ) = capture {
     # lockfile and other processing here along with debug output
     $res = system( 'long_running_program' );
   };
 
   file_write 'out.log', $out;
   send_mail( $err ) if $res;

This has a very big disadvantage. If the long-running program runs too long, and the perl script is started by something like crontab there is no way for you to get at the log output. You will have to wait for it to complete before the captured output is written to the file.

Capture::Tiny::Extended gives you the option to provide filenames for it to use as capture buffers. This means the output from the captured code will appear on the screen and in the file in realtime, and will afterwards be available to your Perl script in the variables returned by the capture function:

   use Capture::Tiny::Extended 'capture';
 
   my ( $out, $err, $res ) = capture(
     sub {
       # lockfile and other processing here along with debug output
       return system( 'long_running_program' );
     },
     {
       stdout => 'out.log',
       stderr => 'err.log',
     }
   );
 
   send_mail( $err ) if $res;

capture_files

Since using hashes in that way breaks a bit of the syntax magic of the capture functions (or makes them harder to read), there exists a sugar function to take the file arguments and pass it on to the capture functions:

   use Capture::Tiny::Extended qw( capture capture_files );
 
   my ( $out, $err, $res ) = capture {
     # lockfile and other processing here along with debug output
     return system( 'long_running_program' );
   }
   capture_files {
     stdout => 'out.log',
     stderr => 'err.log',
   };
 
   send_mail( $err ) if $res;

Capture File Mode Options

For purposes of avoiding data loss, the default behavior is to append to the specified files. The key 'new_files' can be set to a true value on the extra file hash parameter to instruct Capture::Tiny::Extended to attempt to make files. It will die however if the specified files already exist.

   use Capture::Tiny::Extended 'capture';
 
   my $out = capture_merged(
     sub { system( 'ls' ) },
     { stdout => 'out.log', new_files => 1 }
   );

If existing files should always be overwritten, no matter what, the key 'clobber' can be set instead:

   use Capture::Tiny::Extended 'capture';
 
   my $out = capture_merged(
     sub { system( 'ls' ) },
     { stdout => 'out.log', clobber => 1 }
   );

WHY A FORK? ^

The realtime teeing feature was very important for one of my current projects and i needed it on CPAN to be able to easily distribute it to many systems. I had provided a patch for the return value capturing on Github to David Golden a long while ago, but due to being busy with real life, family and more important projects than this he was not able to find time to proof and integrate it and in the foreseeable future won't be able to either. At the same time i lack the Perl file handle, descriptor and layer chops to take full responsibility for Capture::Tiny itself. Usually i would have just written a subclass of the original, but since Capture::Tiny is written in functional style this was not possible.

As such a fork seemed to be the best option to get these features out there. I'd be more than happy to see them integrated into C::T someday and will keep my git repository in such a state as to make this as easy as possible. (Lots of rebasing.)

ACKNOWLEDGEMENTS ^

Capture::Tiny is an invaluable tool that uses practically indecent amounts of creativity to solve decidedly nontrivial problems and circumvents many cliffs the ordinary coder (and most certainly me) would inevitably crash against.

Many thanks to David Golden for taking the time and braving all those traps of insanity to create Capture::Tiny.

SUPPORT ^

Bugs / Feature Requests

Please report any bugs or feature requests by email to bug-capture-tiny-extended at rt.cpan.org, or through the web interface at http://rt.cpan.org/Public/Dist/Display.html?Name=Capture-Tiny-Extended. You will be automatically notified of any progress on the request by the system.

Source Code

This is open source software. The code repository is available for public review and contribution under the terms of the license.

https://github.com/wchristian/capture-tiny

  git clone https://github.com/wchristian/capture-tiny

AUTHORS ^

COPYRIGHT AND LICENSE ^

This software is Copyright (c) 2009 by David Golden.

This is free software, licensed under:

  The Apache License, Version 2.0, January 2004
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