Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

Hello Guys I am very, very new to perl so forgive if this sounds like a stupid question. Is there a way to set up a watch in perl similar to VB or to Cobol? Basically I am trying to watch the data as it moves thru the program. If there is a way to do this, can you please telll me how. Thanks

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Re: Watch in Debug
by ferrency (Deacon) on Aug 03, 2000 at 22:17 UTC
    You probably want to check out the Perl debugger. man perldebug if you're on a unix-like system; otherwise find "perldebug" in your perl documentation.

    Basic idea:

    perl -d my_perl_program

    [download]
    You can then set breakpoints, watch expressions (with the W command), trace through the program, and so on. The docs have the details.

    Alan

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Re: Watch in Debug
by maverick (Curate) on Aug 03, 2000 at 22:19 UTC
    Perl has builtin(?) debugger. perl -d runs the script in the debugger. You might want to check out ddd if you're on a Unix type system (http://www.gnu.org/sorfware/ddd/). It's a GUI debugging package that has support for perl

    /\/\averick

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Re: Watch in Debug
by chip (Curate) on Aug 03, 2000 at 23:56 UTC

    Tied variables can help here. Check out Tie::Watch on CPAN.

        -- Chip Salzenberg, Free-Floating Agent of Chaos

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Re: Watch in Debug
by Cirollo (Friar) on Aug 03, 2000 at 22:22 UTC
    Not sure if this is exactly what you want, but you can set an action to happen before each debugger prompt with the "<" command.

    So, supposing you wanted to watch $foo, you could say
    < print "foo is $foo\n";

    If you want to set a multiple-line command to run, put backslashes at the end of the lines to continue to another line.

    Update: ferrency's method works much better :) Anybody know why 'W' doesn't seem to be in Perl in a Nutshell? Wish I had known about that earlier....

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RE: Watch in Debug
by Anonymous Monk on Aug 03, 2000 at 22:31 UTC
    Thanks guys I really appreciate the help... I will be asking you questions on regular basis. Again Thanks.
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      hey dude, if you're gonna ask us questions, log in, create an account, talk, post answers, or just questions... become part of the community... we're all growing and learning here!
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