Why doesn't {$ifopt FINITEFLOAT ON} compile?

问题

I have the construct:

{$ifopt FINITEFLOAT ON}
  {$message 'FINITEFLOAT option ON' }
{$else }
  {$message 'FINITEFLOAT option OFF' }
{$endif }

in my source and it won't compile! It's got to be something stupid. The error is:

E1030 Invalid compiler directive: '$IFOPT'

at the first line, but it is the FINITEFLOAT it's complaining about. You don't seem to be able to specify anything except the single letter directives like R+ etc as the argument of IFOPT.

Am I missing something here?

回答1:

You are totally correct AFAICT. I don't use $IFOPT often but everytime I do this behaviour annoys me. I have no idea why this is implemented this way.

Edit: There's a Quality Central issue for this.

回答2:

True, you cant :( Thats because IFOPT considered as backward compatibility feature and doesnt work with any extended directives. eg: {$A2} can be set, but not retrieved back

来源：https://stackoverflow.com/questions/3613345/why-doesnt-ifopt-finitefloat-on-compile