type
TMyClass = class of TMyObject;
TMyObject = class
procedure InstanceMethod; //Self = TMyObject, can be virtual
class procedure ClassMethod; //Self = TMyClass, can be virtual
class procedure StaticClassMethod; static; //no Self, really just a global
procedure in a scoped namespace
end;
var
o: TMyObject;
c: TMyClass;
begin
o.InstanceMethod; //if virtual, calls resolved based on actual class
o.ClassMethod; //if virtual calls, resolved based on actual class
o.StaticCalssMethod; //can’t be virtual, resolved on variable type
TMyObject.ClassMethod; //call resolved based on given type
TMyObject.StaticClassMethod; //call resolved based on given type
c.ClassMethod; //if virtual, calls resolved based on actual class
//haven’t tried if this one works, I assume it does:
c.StaticClassMethod; //can’t be virtual, resolved on variable type
end;
From: fpc-devel <fpc-devel-boun...@lists.freepascal.org> On Behalf Of J. Gareth
Moreton
Sent: Sunday, 29 July 2018 07:22
To: FPC developers' list <fpc-devel@lists.freepascal.org>
Subject: Re: [fpc-devel] Compile time functions
Aah, right. Class methods I have used in past projects, but my understanding
is that, in these instances, Self can still be accessed, but represents the
class rather than the object, can be called without an instantiated object, and
still have the issues that they can be virtual and overridden (something i'm
disallowing with pure functions because of the initial complexity of
determining which version of a method to call).
Can you clarify, Sven, with "static" and "class"?
Gareth aka. Kit
On Sat 28/07/18 23:11 , "Dmitry Boyarintsev" skalogryz.li...@gmail.com
<mailto:skalogryz.li...@gmail.com> sent:
These are known as “class” methods (rather than “static”) in object pascal.
Thanks,
Dmitry
On Saturday, July 28, 2018, J. Gareth Moreton <gar...@moreton-family.com
<javascript:top.opencompose('gar...@moreton-family.com','','','')> > wrote:
Aah, right.
I'm probably being rather dumb here from not having used them before, but do
you mean things like this?
type
TNewClass = class
function Special: Boolean; static;
end;
I gather you can't access Self in such methods.
Gareth aka. Kit
On Sat 28/07/18 20:37 , "Sven Barth" pascaldra...@googlemail.com
<javascript:top.opencompose('pascaldra...@googlemail.com','','','')> sent:
J. Gareth Moreton <gar...@moreton-family.com <mailto:gar...@moreton-family.com>
> schrieb am Sa., 28. Juli 2018, 19:34:
I did wonder about that, but wasn't sure how it would affect things where
inheritance is concerned. I dare ask, do you have an example of a class method
that you would consider pure?
They don't have inheritance. If they have the modifier "static" they really are
simply scoped functions or procedures. They can even be assigned to non-"of
object" procedure variables.
Regards,
Sven
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