Re: Event handlers...

swansnow wrote: 
and it is this classname prefix which is missing from your code and
so upsetting the compiler.... So method code _must_
know which instance is calling it.

Does this mean, then, that an event handler has a "self" variable? 

Exactly.

What if the event handler is a class procedure of a different class,
when I call it, what is in the "self" variable?

It's the same as it would have been if you'd called the class procedure directly. An event handler is little more than a delayed call.

Within a class method, "Self" refers to the class itself rather than an instance of the class.

class procedure TSwan.Snow;
begin
  Assert(Self = TSwan);
  Assert(Self.InheritsFrom(TSwan));
end;

The second Assert will always pass. The first will pass when the method is called on TSwan, but not when it's called on a descendant class of TSwan.

(Is it even possible to
have the event handler be a class procedure?)

Yes, it's possible. In your case, it's probably exactly what you need since you said you don't have any objects. you'll have to define a class, but you'll never have to instantiate it.

How would I set up a class to use an event handler defined in a
different class?

There's really nothing special about it at all. An event handler never cares which class a method was declared it. The event handler merely needs to know which class that is. As long as you provide *something*, it can be anything you want.

I have some kinds of events which I want handled in
the same way across multiple forms, like validating keypresses...



--
Rob
.

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