How to avoid violating the DRY principle when the boolean expression of a while loop is reassigned every loop pass?

Question

Both

while MyFunction(1, 2, 3) > 0 do
  begin
    Temp := MyFunction(1, 2, 3);
    ShowMessage(IntToStr(Temp));
  end;

and

Temp := MyFunction(1, 2, 3);
while Temp > 0 do
  begin
    ShowMessage(IntToStr(Temp));
    Temp := MyFunction(1, 2, 3);
  end;

violate the DRY principle because there are two calls to MyFunction when only one is necessary.

Answer 1

Easy,

  function dotemp(a,b,c:integer;var value : integer):boolean;
  begin
    value:a*b+c;
    result:=value>0; 
  end;

  begin
    while dotemp(a,b,c,temp) do
        begin
           Operateontemp(temp);
         end;
  end;

Pascal has no lvalue assignments, but it DOES have var parameters.