This isn't a perl specific point, but coders need to be able to distinguish between situations where they should die/assert/explode/etc, and situations where they need to be able to handle the bogus input.

Imagine you're writing a web browser. It connects to some server accross the web, downloads some content and tries to parse it as HTML, images, flash, sound... There's quite a lot of code, so it's useful to add assertions in many functions.

However, you can't add an assertion like this without it failing (pointlessly) on many many sites: 

if (m{<body>})
{
    die "Mismatched tags!" unless m{</body>};
}

[download]

In general, only assert over items that you (or someone in your team) is in control of. Never assert about items that you can't control, such as content from the www or a user - you'll just have to find some way of coping with errors in that.

Oh, and remember that you'll need to be able to tell the difference, and that there shouldn't be a gap between the things that are asserted and the things that are handled...

In reply to Re: Your use of assertions in Perl ? by wol
in thread Your use of assertions in Perl ? by ady

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