> On 29 Nov 2022, at 14:34, Anony Mous <fyng...@gmail.com> wrote: > > > As it stands now, to create a local scope, you must define a function. > > However, there are many cases where various things can reasonably be done > inline. Preparatory code is often done this way. > > Good coding practice is generally accepted to be that variables are local if > at all possible. However, in direct, inline Python code, we're inherently > creating variables with a global scope. > > We don't actually need a function for this kind of code; but a local scope > would often be valuable (as we see with lambda.) Moving things off into a > function can create a circumstance where we have to go looking for the > function. When something is a "one-shot" as in global preparatory code, > that's doing more work, and creating more indirection, than needs actually be > done. But global operations have their own pitfalls, one of which is variable > collisions. So Python sort of drives us to make "one-use" functions where > lambdas are insufficient to the case in order to control locality. > > You can end up writing things like... > > def PrepOne(): > for MyCount in range(0,10): > pass > > PrepOne() > > ...which achieves the locality desired for variable MyCount, but is clunky. > It also clutters the global namespace with prepOne, which has no good reason > to exist. > > So I'm thinking of something along these lines: > > local: # <== or whatever syntax makes sense > for MyCount in range(0,10): > pass > > So in that example, the code is inline - runs as part of the global, > sequential code execution - but the variable MyCount is local and goes "poof" > once the local: scope is exited. > > This is the scoping equivalent of a pair of curly braces in c and c++. I > would like to see it be nestable, as scopes are in c/c++: > > local: # <== or whatever syntax makes sense > for MyCount in range(0,10): > local: > for YourCount in range(0,MyCount+1) > pass > > There, MyCount is available in both scopes (the first local: is an enclosing > scope) and YourCount is available only in the second local: scope. > > Or, local: could be very strict, and require further syntax to incorporate a > previous scope, something like this: > > local: # <== or whatever syntax makes sense > for MyCount in range(0,10): > local: > incorporate MyCount # <== or whatever syntax makes sense > for YourCount in range(0,MyCount+1) > pass > > Lastly, I suggest that the global keyword be used to expose global scope > variables, just as it is within def functions: > > TheirCount = 10 > local: # <== or whatever syntax makes sense > global TheirCount > for MyCount in range(0,TheirCount): > local: > for YourCount in range(0,TheirCount) > pass > > This would also be useful within normal functions, and again allows the > program flow to be linear rather than calling a function-within-a-function.
This has been discussed here before and rejected. The ways scoping works in python is very hard to change as you are asking for i think was a major reason to reject. Barry > _______________________________________________ > 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/3ZEM5FPYWI24G3EOM3HA2I4RKWCMR3J5/ > Code of Conduct: http://python.org/psf/codeofconduct/
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