Re: scope of variables
- Posted by ChrisB (moderator) Dec 31, 2010
- 2671 views
My vote would be against allowing variable creation within loops(etc).
Chris
This was a design decision made way back when it was decided to allow one to declare a variable anywhere inside a routine.
One of the arguments for allowing this 'shadowing' of variables, and creating a new instance of a variable within a while / for (etc) loop was that it allows Euphoria to behave like other languages.
Euphoria is not like other languages. To allow creating another variable within a loop (or other instances within a function / procedure that has already been defined within that function procedure) is simply asking for trouble. Its just not necessary.
I don't believe that existing code will be broken, as this method has never been allowed.
Jeremy has proposed that this be linked to the concept of shadowing a variable in the local file vs a private variable in a routine.
E.g., that this be made illegal:
integer i function s() integer i = 1 return i end function
He's all-or-nothing on this point (well, AFAICS and IMVHO, with statement option aside).
This is what would break existing code (all the way back to 1.x).
This actually raises a counter argument. Euphoria already had this feature. We've had shadowing all the way back since the 1.0 days of Euphoria, yet never had a problem before. Jeremy is saying that allowing shadowing in the new scopes can cause all sorts of bugs - but is there an Euphoria example from the past that demonstrates this?
If not, then why assume that it would cause a problem with the new scopes?
I think comparision with PHP (which does things like scoping quite differently than Euphoria, or C for that matter) is less valid than an Euphoric example.
Ah, I see. Well obviously that's absurd. You can't change something that fundamental without expecting a huge backlash. But I still think that 'microscoping' within loops inside a function/procedure is wrong, and would lead to great confusion.
PS - I'm not a language designer, just a simple user.
Chris
