Greg Ewing writes: > You've probably never seen the one I'm thinking of. It's a > proprietary, vaguely VB-like language used for scripting a > particular application. It doesn't work like Lua, but it > does have scoping rules that can lead to some surprising > results.
By contrast, Lisps (at least Lisp2s like Emacs Lisp and Steel Bank Common Lisp) have #'makunbound, and this is an unbound symbol error in both: (defvar x 1) (defvar result '()) (let ((x 2)) (push x result) (makunbound 'x) (push x result) # error is signaled here result) Since Common Lisp is the world's most overengineered language, I would guess this scoping rule is deliberate. > One particularly weird thing it does: if you don't declare > a variable (it has optional declarations) it will *usually* > infer it to be local if you assign to it. But if the first > assignment is in a conditional branch of the code, it seems > to get confused. If you do this: > > if something then > x = 5 > else > x = 7 > end if > > and later refer to x, it complains that x hasn't been defined. > Go figure. Some versions of GCC would occasionally complain that "x might be used uninitialized" in similar code in C, too. Spent a lot of time on such warnings, sometimes GCC was right, but sometimes it just didn't make sense. Apparently compiling such code, at least with optimization, can be hard. _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/7Y2C5HKYCOUGG3JAAPXEIUGH2JM7AO3T/ Code of Conduct: http://python.org/psf/codeofconduct/
