It seems to me that the majority of recommended programming practices here on PM involve avoiding dynamic scoping as much as possible. Examples:

• Using strict means making the vast majority of your variables lexical my vars.
• How many Anonymous Monks have been scolded (with good reason) for trying to use a variable as the name of another variable? String references (which only work in dynamic scoping) are generally considered a Bad Thing around here; we usually recommend hashes for this.

I've tried to think of situations when dynamic scoping turns out to be convenient. Here's what I've come up with:

• To facilitate object polymorphism, method calls should be looked up at runtime.
• Importing symbols into the caller's namespace: Most commonly used when importing subroutines. However, importing variables can be done lexically: why not just pass a reference in the use statement?
• AUTOLOAD
• Builtins, @_, $_, etc. However, Perl6 is moving away towards dynamically scoped builtins. It's my understanding that $_ will be lexical. Also, things like $/ and $\ will become filehandle properties.
• Aliasing *_ = \$var. But again, Perl6 will allow this to happen lexically with the := operator (if I'm not mistakened).
• Laziness when writing one-liners and such; no need to declare vars.

It dawned on me that the problems addressed well by dynamic scoping involve only subroutines (including method calls). I don't see any other big problems addressed that can't be dealt with lexically. I don't pretend to know a lot about language design, so I may be missing something obvious here. Anyway, after thinking about this for a while I concluded, why not just make subroutine/method calls dynamically scoped and force everything else lexical?

Perhaps the answer is just as simple as "Perl shouldn't force anything, even our scoping preferences." But I want to know what you all think. Also, is dynamic scoping still hanging around just for posterity? Is Perl moving away from dynamic scoping?

Thanks,
blokhead

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