[Python-Dev] LOAD_NAME & classes (original) (raw)

Scott Gilbert xscottg@yahoo.com
Wed, 24 Apr 2002 00:37:03 -0700 (PDT)

--- Tim Peters <tim.one@comcast.net> wrote:

This is actually what happens in Icon, which also lacks declarations (in the same sense Python lacks them: it doesn't lack them ). The difference is that all variables are global by default in Icon, and you need to explicitly say "local x" if you want a local var instead. That's error-prone for sure, by not quite as much so as Perl (where x is also global by default, but "local $x" sucks you into dynamic scoping; it does not in Icon).

A few corrections. New variable names were local by default. The only way to get a global variable was to make a "global varname" statement at the global scope. Icon gave you a None-like value, &null, for your variables if you hadn't already assigned to them somewhere. So strictly speaking, you could read a variable before writing to it, and a declaration (first initialization) wasn't necessary the same way it is in Python.

Using "local x" was strongly recommended because (a) you could use the -u switch of icont to warn you when you didn't declare your locals (usually from typos), and (b) in case you forgot that you used the same name as a global somewhere else, or more likely you "link"ed with a file that had global declarations you weren't aware of.

So it really wasn't so error prone. (Icon's not even close to Perl in this regard. :-)

Cheers, -Scott

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