Peter Vreman a écrit :
Hello,
Let's say there is a function
function ICmp(A,B: PBigInt): SInt32;
and a TBigIntList class having the following method that can
sort the list according to Cmp
procedure TBigIntList.Sort(Cmp: TBigIntCompareFunc);
with, of course,
type TBigIntCompareFunc = function(A,B: PBigInt): SInt32;
Now, if ICmp is not overloaded, there is no problem, the call
L.Sort(@ICmp);
works. But, of course, it doesn't work if ICmp is overloaded.
In fact, we cannot have both overloaded functions _and_ the
the possibility to use them as variables. Yes, there are
ways to fix the problem (no overload or embedding the
overloaded functions in local functions) but none is really
satisfying.
Would it be possible to get something like
L.Sort(@ICmp(PBigInt,PBigInt));
in case ICmp is overloaded? If we could add the parameter
types, there would be no more ambiguity, the compiler would
There is ambiguity with a normal call to the function. The compiler sees
the ( and thinks it is parsing a call to Icmp().
Yes. I already encountered this problem when using a function
variable.
Ok. And this way
L.Sort(@ICmp:PBigInt:PBigInt);
and if ever ICmp was overloaded but had no parameter
L.Sort(@ICmp);
Well, of course, I don't know the compiler enough to propose
something clean and not ambiguous but the problem is not to find
a way to tell the compiler "Use this routine and not an other
one", I am sure it is not too much difficult. No, the problem is
"Is it easy to modify the parser in order to implement it?".
It would really be nice to be able to use overloaded routines as
non overloaded ones. At the moment, in order not to lose the
possibility to transmit routines to lists, like
procedure TBigIntList.ForEach(Proc: TBigIntBinaryOperator;
A: PBigInt; Test: TBigIntTestFunc=nil);
// add A to all even integers of the list
L.ForEach(@IAdd,A,@IIsEven);
which is much faster than
for i := 0 to L.Count-1 do
if IIsEven(L[i]) then IAdd(L[i],A);
I suppressed most overloaded routines by adding suffixes: IAddUI32,
IAddSI32, IAddUI64, etc. It works but that's rather ugly :-)
To conclude, if you cannot add such a feature to FPC, you cannot.
Don't worry, FPC is already very good as it is.
mm
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