fx logical operations should short circuit
Posted: 2015-08-10T14:41:55-07:00
In fx, the logical operations && and || always evaluate both arguments. This is wrong. It will also greatly expand the time for the script I have just written. The change to the source code is minimal:
old:
new (untested)
Some developers may feel that this could possibly break some scripts. Breaking scripts is a "bad thing" and should be avoided. In this case, however, breakage can only occur when expressions have side effects--and none of the FX operations or primitives have side effects. The only effect of the change will be to make some scripts faster.
If the only hindrance to accepting the change is testing, and if I can be assured that the change will be made after the test is done, I will be happy to do the test.
old:
Code: Select all
case LogicalAndOperator:
{
gamma=FxEvaluateSubexpression(fx_info,channel,x,y,++p,beta,exception);
*beta=(alpha > 0.0) && (gamma > 0.0) ? 1.0 : 0.0;
return(*beta);
}
case LogicalOrOperator:
{
gamma=FxEvaluateSubexpression(fx_info,channel,x,y,++p,beta,exception);
*beta=(alpha > 0.0) || (gamma > 0.0) ? 1.0 : 0.0;
return(*beta);
}Code: Select all
case LogicalAndOperator:
{
if (alpha <= 0.0)
return (*beta=0.0); // alpha is false: the AND is false
gamma=FxEvaluateSubexpression(fx_info,channel,x,y,++p,beta,exception);
*beta= (gamma > 0.0) ? 1.0 : 0.0;
return(*beta);
}
case LogicalOrOperator:
{
if (alpha > 0.0)
return (*beta=1.0); // alpha is true: the OR is true
gamma=FxEvaluateSubexpression(fx_info,channel,x,y,++p,beta,exception);
*beta=(gamma > 0.0) ? 1.0 : 0.0;
return(*beta);
}
If the only hindrance to accepting the change is testing, and if I can be assured that the change will be made after the test is done, I will be happy to do the test.