[fpc-devel] Local variable names and colision with attributes/properties names

Jonas Maebe jonas.maebe at elis.ugent.be
Thu Sep 27 16:01:08 CEST 2012

On 27 Sep 2012, at 15:51, Marcos Douglas wrote:

> What is the advantages to the compiler return the error bellow?
> ERROR: unit1.pas(31,3) Error: Duplicate identifier "FooVar"
> Why the compiler do not respect the scope, ie, the local variable
> should have the preference, I'm not right?

Yes, but the human brain is very good at confusing such things, and  
it's very easy to accidentally assign something to a local variable  
instead of to a field.

> Not? Why I can use a unit name as a property in my class, so? (see
> bellow the "StdCtrls" property name).

Because the compiler only checks for identifiers defined in the  
current unit. You also cannot assign anything to a "unit", nor "read"  
from it, so there is generally less ambiguity (it still can exist in  
case the field is a record/class/object and contains fields that have  
the same name as global variables declared in the unit, but that's not  
exactly common).

> If I use {mode delphi} I can compile... I know. Why not in {mode  
> objfpc} too?

Because {$mode objfpc} makes different trade-offs compared to {$mode  
delphi}. You can pick the one you like best.

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