With or Using

[Carlos Ribeiro]

At 16:11 18/04/01 +0000, David C. Ullrich wrote:
>It's in Delphi all right. Now find five Delphi experts and ask them
>whether they think it's a good idea.

I dont know if the expression "Delphi expert" applies to myself; however, I 
did happen to be a beta tester of Delphi 1 (when it was distributed in 
floppies :-). In Delphi, "with" is a good idea, but not so in Python. Why 
it is different? Because both languages have different type models.

Delphi uses static types. So it is possible to know, in a unambiguous way, 
what member is being assigned in a "with" clause. This is important for 
both the compiler *and* the programmer. In fact, some Delphi experts may 
argue that the "with" construct should be avoided. I believe it is a matter 
of personal taste, because a careful read will always reveal wich variable 
(or member of) is getting assigned.

Python uses dynamic types. It is impossible to know in advance which 
attribute will be referenced at runtime. Member attributes may be added or 
removed from objects on the fly. This would make it impossible to know, 
from a simple reading, what attribute is being read - a local one, a global 
one, or a member attribute.

The same argument also applies to the use of self, that is mandatory on 
Python, but not on Delphi. In Delphi all you have is a implicit "with" 
clause on self on the beginning of every method implementation.


Carlos Ribeiro