> On Apr 13, 2019, at 2:45 PM, Martin Frb <[email protected]> wrote:
>
> Well that doesn't work. Unless you wrote pthread_create (or whatever other
> function).
> Because the "opitonal" parameter (which really only serves as documentation
> hint) is itself optional.
> So if the author of the code that you intend to use did not put "optional" in
> there, you are still where you are now. And you cant force the author to put
> it there. Same as you cant force the author to put it on top of the
> documentation.
>
> Already today the author could add a comment (even pasdoc) to the
> declaration. And it serves the same effect.
Sure, if it’s not used then it’s not very helpful. :) Comments are the same
effect? Then why not prefer comments for “const” params or even public/private
sections. Surely this isn’t a good idea:
type
TClassName = class (TObject)
{private}
m_var: integer;
{public}
procedure DoThis({const} p: TPoint);
end;
They’re just simple hints that provide some compile time errors.
>
> Also the is a difference between:
> - the parameter is nil-able (better term that optional, optional has a
> different meaning)
> - the compiler needs to enforce an check for "<> nil"
>
> If the parameter is only stored, for later usage, then the nil can be stored
> too. There is no check needed for that.
> It will be needed later in some other function, but the compiler can not know
> where that may be.
>
> You can even call methods on an object that is nil. So long as they are:
> - not virtual, nor call virtual methods themself
> - do not access "self" without prior check that it is not nil
All true. I only propose this for cases where nil could be passed/returned and
the programmer can be given more information and forced to check since this is
the pattern they were supposed to do anyways. It’s not a magic catch-all, just
a minor markup thing like “const” is.
Regards,
Ryan Joseph
_______________________________________________
fpc-pascal maillist - [email protected]
http://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
