Hi

I have a component derived from TCustomComboBox that saves state info in
the registry.  I do something like this on destroy

    with TRegistry.Create do
    Try
      RootKey:=HKEY_CURRENT_USER;
      //  blah blah blah
    Finally
      CloseKey;
      Free;
    end;

When the component is freed, I get 'component has no parent window' error.  
I couldn't figure out what the problem was.  Finally I tried using a
variable instead.

    reg:=TRegistry.Create;
    with reg do
    Try
      reg.RootKey:=HKEY_CURRENT_USER;
      // blah blah blah
    Finally
      reg.CloseKey;
      reg.Free;
    end;

And it was fine.  Why?

-- luu

Please remove the underscore _ in my address when replying by email

In article <6gv1qo$...@bgtnsc02.worldnet.att.net>,
  "Luu Tran" <luu_t...@geocities.com> wrote:

David C. Ullrich

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:     with TRegistry.Create do
:     Try
:       RootKey:=HKEY_CURRENT_USER;
:       //  blah blah blah
:     Finally
:       CloseKey;
:       Free;
:     end;

        you have to assign a TRegistry variable. what you've got
above is the same as saying "TRegistry.Create.RootKey:=HKEY_CURRENT_USER".
This doesn't make sense. TRegistry.Create returns a pointer to a
TRegistry variable.

:     reg:=TRegistry.Create;
:     with reg do
:     Try
:       reg.RootKey:=HKEY_CURRENT_USER;
:       // blah blah blah
:     Finally
:       reg.CloseKey;
:       reg.Free;
:     end;

: And it was fine.  Why?

: -- luu

--
                              Bed
                bedn...@yallara.cs.rmit.edu.au
            http://www.geocities.com/Hollywood/2430
2nd Year Comp Sci @ RMIT & Programmer @ AMC Enterprises Pty Ltd

Andrew James Bednarz schrieb in Nachricht
<6hjsbi$rs...@goanna.cs.rmit.edu.au>...

I've found that the With statement isn't all that reliable and I can't
really come up with an explanation either. It seems that sometimes its
using a variable from the TForm parent object (self) that has the same
name as the component or object I'm using in the With statement. It
doesn't do it all the time which I find strange.

I suppose I'd need to look at the compiled code to see where the
Compiler is going wrong but I don't have the time. Besides the With
statement makes tracing code more difficult and sometimes the code isn't
as clear so I don't use it anymore.

Mitch Wolberg,
RockWare, Inc.

No memory leaks or other disadvantages because of try/finally .

Regards, W.L.

In article <353F4E1C.5198A...@dnvr.uswest.net>,
  Mitch Wolberg <rk...@dnvr.uswest.net> wrote:

with AnObject do AMethod;

where AMethod is not actually a method of AnObject. If the form
(or some other object "containing" this code) has a method named
AMethod then this will call the form's AMethod method.

        Or you can go wrong with nested with's, where both
objects have methods with the same name. Or...

        Or there _could_ be actual problems with with, but
I'm not convinced just because you say so, you have to give
an example (and because of the nature of the common easy
errors it has to be a _complete_ example - when we see a
snippet there's no way to tell whether the code surrounding
the snippet is the cause of some error as above.)

David C. Ullrich

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