If it is only between int and double, maybe this will help
have on overload function
class function TMedian.Div(Value, Divider: Integer): Integer; // Result
:= Value div Divider
class function TMedian.Div(Value, Divider: Double): Double; // Result
:= Value / Divider
then the compiler chooses dependent on T.
On 05/04/2010 15:04, leledumbo wrote:
consider the following generic class declaration:
{$mode objfpc}{$H+}
type
generic TMedian<T> = class
class function Find(x: array of T): T;
end;
class function TMedian.Find(x: array of T): T;
var
i, j, Middle: Integer;
Temporary: T;
begin
// Use truncated selection sort to find median
Middle := (High(x) + 1) div 2;
for i := 0 to Middle do
for j := 1 to High(x) - i do
if x[j]> x[j - 1] then begin
Temporary := x[j];
x[j] := x[j - 1];
x[j - 1] := Temporary;
end;
if Odd(High(x)) then
// When High(x) is Odd, there are an even number of elements in array.
// Define median as average of two middle values.
Result := (x[Middle] + x[Middle - 1]) / 2 //<-- This line
else
// When High(x) is Even, there are an odd number of elements in array.
// Median is the middle value.
Result := x[Middle];
end {Find};
How can I make it work such that:
type
TMedianInteger = specialize TMedian<Integer>;
TMedianDouble = specialize TMedian<Double>;
is valid?
See the line marked with<-- above, due to semantic of /, I can't use
integer because / returns floating point value, Extended to be precise. If I
change it to div, it won't work (correctly) for floating point values,
because the precision is lost. Typecasting to T won't work either because
Extended can't be converted to LongInt (larger to smaller type problem).
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