[Bug 191] New: Cannot refer to member variable in default value for method parameter

[Don Clugston]

Bruno Medeiros wrote:
> BCS wrote:
>> Deewiant wrote:
>>> All I can find about default parameters in the spec is at the 
>>> "Functions" page,
>>> where they pop out of the blue in the phrase "A function parameter's 
>>> default
>>> value is not inherited", which is all that's said about them. The 
...
>>
> Hum, quite a catch you got there! Not only should it be better 
> documented, but maybe it shouldn't work this way.
> Perhaps the default values should be set not at the call site, but by 
> the function itself (thus depending on it's run-time type, and not it's 
> compile-time type),

I'm almost certain that default values should work that way. They should 
just be syntactic sugar for overloaded functions.
Right now, they have the same problem which C++ has -- there's no way 
that a template can find out what the default values are, and the 
default values can't be used by function pointers or delegates.
So for example,

void foo(int a, int b=2, int c=3) {}

void goo(int a, int b, int c) { }
void goo(int a, int b) { goo(a, b, 3); }
void goo(int a) { goo(a, 2, 3); }

void function(int) boo;

foo(7); // ok
goo(7); // ok

boo = goo; // ok
boo(5);

boo = foo; // doesn't compile -- why not?
boo(5);


  or maybe it could be as Oskar's idea ("if D
> inherited default values and forbade them to be redefined in derived 
> classes")