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| passing functions/procedure to other functions/procedures |
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Can I pass a function or procedure to another function or procedure?
Yes. You must declare a procedure or function type to use as the parameter type, then you can pass the address of the procedure that you wish to pass. You must be careful to pass functions or procedures that are compatible with the function or procedure expected, as little error checking will be provided by the compiler.
Example:
type
AFunctionType = function(IntIn : integer) : integer;
function AddProc(IntIn : integer) : integer;
begin
Result := IntIn + ;
end;
function SubProc(IntIn : integer) : integer;
begin
Result := IntIn - 2;
end;
procedure PassAFunction(var IntIn : integer;
fn : AFunctionType);
begin
IntIn := fn(IntIn);
end;
procedure TForm .Button Click(Sender: TObject);
var
i : integer;
begin
i := 0;
PassAFunction(i, @AddProc);
ShowMessage(IntToStr(i));
PassAFunction(i, @SubProc);
ShowMessage(IntToStr(i));
end;
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