Exception Handling

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3 total messages Started by mike Tue, 10 Aug 2004 14:41

#5480

Author: mike
Date: Tue, 10 Aug 2004 14:41

43 lines
1898 bytes

Could someone explain to me how to handle an exception when trying to open a
connection from a TClientSocket.

Heres what is happening;

I issued the following.

        try
        {
                       Form1->ClientSocket1->Open()
;
           ;
        }
            catch (...)
            {
            ShowMessage("Error");

            }

Now I have purposly placed an invalid host into the Form1->ClientSocket1 so
that an exception will occur, and it does.

I also have the Error Event returning 0 if I get an error.

So what happens is this.

The first time I issue the open command, the Disconnect event is fired, and
then the Exception displays a message. No error even is fired.

If I issue the open command again, no Disconnect event is fired, an Error
event is fired, No Exception is fired.

If I repeat the open again, the first condition occurs again.


So I don't understand how to catch the exception, or why the actions are
different between the first open and the second open.

Can someone help me with this.

Thanks for any information.

Mike

Re: Exception Handling

#5482

Author: Remy Lebeau (TeamB)
Date: Tue, 10 Aug 2004 17:23

18 lines
1560 bytes

"mike" <mfbrowne@earthlink.net> wrote in message
news:4118e06b@newsgroups.borland.com...

> Could someone explain to me how to handle an exception
> when trying to open a connection from a TClientSocket.

If you are using the ClientSocket in non-blocking mode then you can't use
exception handling when calling Open() as any exception thrown will be
delayed, thrown long after Open() returns and your exception handling is
exited.  You should use the OnError event to catch errors, and you can
optionally then set the ErrorCode parameter to 0 to prevent exceptions from
being thrown at all.

Otherwise, use the ClientSocket in blocking mode instead.


Gambit

Re: Exception Handling

#5487

Author: mike
Date: Tue, 10 Aug 2004 21:49

38 lines
2163 bytes

Remy,

I do have the on error event defined, however the client socket does not
create an on error event the first time the open is called with an invalid
host. It does the second time it is called, but not the third and so on.

So if I use the Client Socket in blocking mode, do I have to create the
thread and such as with a blocking ServerSocket. If so do you have sample
code that shows what is required.

Thanks

Mike


"Remy Lebeau (TeamB)" <gambit47.no.spam@no.spam.yahoo.com> wrote in message
news:4119046a$1@newsgroups.borland.com...
>
> "mike" <mfbrowne@earthlink.net> wrote in message
> news:4118e06b@newsgroups.borland.com...
>
> > Could someone explain to me how to handle an exception
> > when trying to open a connection from a TClientSocket.
>
> If you are using the ClientSocket in non-blocking mode then you can't use
> exception handling when calling Open() as any exception thrown will be
> delayed, thrown long after Open() returns and your exception handling is
> exited.  You should use the OnError event to catch errors, and you can
> optionally then set the ErrorCode parameter to 0 to prevent exceptions
from
> being thrown at all.
>
> Otherwise, use the ClientSocket in blocking mode instead.
>
>
> Gambit
>
>

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