On Wed, 30 Oct 2013, Jonas Maebe wrote:
On 30 Oct 2013, at 12:09, Sven Barth <pascaldra...@googlemail.com> wrote:
Am 30.10.2013 11:59, schrieb Jonas Maebe:
The tdynarray type is not visible in the program because u1 is not in its uses
clause (it's not in scope whatsoever), and nevertheless there is no problem to
use it. It's of course not exactly the same (tdynarray isn't declared as
private to u1), but at the scope visibility level it is the same situation as
far as I am concerned.
Hmm... but here the compiler can not know whether the unit using u2 has unit u1
in scope or not. In case of private and protected types the compiler can know
however that code declared externally can never have access to it
It can, as demonstrated by the example that started this thread. The type
identifier may not be visible, but entities that have this type can be. Just
like in the unit example.
You must admit that in the case of a function result type, that is a bit awkward,
since you will never be able to declare a properly typed variable to hold the function
result. In the case of a record or class type, that is particularly awkward since you
will be forced to use a "with" to access the various fields.
Type
TMyClass = Class
private
type myrec = record
a,b : SomeOtherType;
end;
public
function MyFunc : Myrec;
end;
You cannot do
Var
c : TMyClass;
r : myrec; // will fail.
begin
r:=c.myfunc;
Writeln(r.a,' ',r.b);
end;
you can only do
Var
c : TMyClass;
begin
with c.myfunc do
Writeln(r.a,' ',r.b);
end;
Michael.
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