if I have this test program below:
program testi;
{$INTERFACES CORBA}
uses sysutils;
type
IInterfaceA = interface
procedure Increment ;
end;
{ TObjectA }
TObjectA = class(IInterfaceA)
Value : Int64;
procedure Increment;
end;
var
c : int32;
i : IInterfaceA;
obj : TObjectA;
aTime : TDateTime;
{ TObjectA }
procedure TObjectA.Increment;
begin
Inc(Value);
end;
begin
obj := TObjectA.Create;
try
aTime := now;
for c := 1 to 100000000 do
obj.Increment;
aTime := now - aTime;
Writeln('Object call Time Taken Seconds:', aTime*24*60*60);
finally
FreeAndNil(obj);
end;
obj := TObjectA.Create;
try
aTime := now;
i := obj;
for c := 1 to 100000000 do
i.Increment;
aTime := now - aTime;
Writeln('Interface call Time Taken Seconds:', aTime*24*60*60);
finally
FreeAndNil(obj);
end;
Readln;
end.
The run results:
Object call Time Taken Seconds: 2.1899964194744825E-001
Interface call Time Taken Seconds: 2.7999999001622200E-001
so, the time difference is about 27%
My question is, where is this extra time spent?
I am assuming an interface variable has a table with entries storing (
pointer to the object instance AND an offset of method address in the
Virtual Method Table of that object.)
Am I correct?
What is the memory occupied by the interface variable?
I know the sizeof(i) = 8 (in 64 bit windows), but what is the size of
the instance?
I cannot find any of this info on the web.
Thanks for your answer in advance.
Dennis
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