How can I have variable assertions in Perl?

Question

How can I check that a variable has a specific value in Perl? Is there a command to stop a script's execution to look up some of it's variables?

I wonder if I can use the Pythonic practice of inserting:

    assert 0, (foo, bar)

to debug scripts in a debuger-less way?

Answer 1

There is a script at PerlMonks that introduces a fast assert method.

Speed is important since Perl is interpreted and any inline checks will impact performance (unlike simple C macros for example)

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I am not sure if these things are going to be directly usable.

• there is Test::Harness in default installs. Here is a starter tutorial. The more recent module is TAP::Harness
• A slower version along the lines you talk is Sub::Assert

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Ok! This is what i was looking for -- PDF Warning: Test-Tutorial.pdf. The Test::Harness is used for writing Perl module tests.

Answer 2

A quick CPAN search suggests Carp::Assert.

Answer 3

See Carp::Assert.

Answer 4

Smart::Comments are nice.

Answer 5

$var_to_check =~ /sometest/ or die "bad variable!";

I tend to throw things like this in my code, and later use a find and replace to get rid of them (in production code).

Also, 'eval' can be used to run a section of code and capture errors and can be used to create exception handling functionality. If you are asserting that a value is not 0, perhaps you want to throw an exception and handle that case in a special way?