I didn't realize that extreme programming and Perl were mutually exclusive.

Did I say so? I was merely hinting at PerlMonks not being wikipedia or an eplain-me-the-world site - and saying that I find asking arbitrary questions (of the kind the OP and my reply are) not appropriate for PerlMonks - even if they carry the terms "scope" and "programming", or even "extreme programming". I did that in a somewhat terse way, but no flame was intended.

Of course extreme programming "is an interesting and useful subject to be discussed at a site meant to be useful to Perl programmers" - but the OP didn't do that, there's no discussion whatsoever, they've merely asked to explain them a term in the context of - extreme programming, not perl!

Now that particular question would really have better been asked in comp.programming.extreme.

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