Solved

TRY EXCEPT FINALLY

Posted on 2003-10-29
4
424 Views
Last Modified: 2012-03-15
Hi, i was wondering if it is possible to trap an error in a robust way using the
try and except and finally. Before the form shows it will search for a particular
directory such as C:\TEST\BACKUP2 and it is not found on the then it will raise an exception and does not continue the loading of my program. is it possible?
0
Comment
Question by:therooster
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
4 Comments
 
LVL 11

Expert Comment

by:robert_marquardt
ID: 9648265
That is what try except finally is for.

try
  SearchForDirectory();
  Found := True;
except
  Found := False;
end;

Now SearchForDirectoryis either successful and Found := True is executed or the exception hits and
Found := False is executed. The exception is swallowed.

If you want to have the exception raised again then call "raise;" in the except block.
Alternatively use
try
finally
end;
which does not catch the exception, but executes the block of "finally end" no matter if an exception occurs or not.
It also executes even if you call Exit inside "try finally".

If you want both then you have to use two nested try blocks.
try
  try
  except
  end;
finally
end;
0
 
LVL 17

Accepted Solution

by:
geobul earned 250 total points
ID: 9648615
Hi,

You may do that in you project unit this way:

program Project1;

uses
  Forms,
  Unit1 in 'Unit1.pas' {Form1},
  FileCtrl, // DirectoryExists
  Dialogs; // ShowMessage

{$R *.RES}

var d: string;
begin
  d := 'c:\test\backup2';
  if DirectoryExists(d) then begin
    Application.Initialize;
    Application.CreateForm(TForm1, Form1);
    Application.Run;
  end else begin
    ShowMessage('Directory '+d+' does not exist! Terminating ...');
  end;
end.

Regards, Geo
0
 
LVL 17

Expert Comment

by:geobul
ID: 9648654
The same thing could be done in a form's OnCreate event:

uses FileCtrl;

procedure TForm1.FormCreate(Sender: TObject);
var d: string;
begin
  d := 'c:\test\backup2';
  if not DirectoryExists(d) then begin
    ShowMessage('Directory '+d+' does not exist! Terminating ...');
    Application.Terminate;
  end;
end;

Regards, Geo
0
 

Expert Comment

by:_JHL_
ID: 9672918
Hi, the Try Except way it`s a good way to prevent a crash of the programa, or an error that you don't want to raise.
The sintax that I usually do is:
try
  {Here the code that probably raise an exception}
except
 {Here the code alternative if there is an exception OR
exit; {to terminate the process OR}
application.terminate;{to terminate the program}
end;

I hope it helps

JHL
0

Featured Post

On Demand Webinar - Networking for the Cloud Era

This webinar discusses:
-Common barriers companies experience when moving to the cloud
-How SD-WAN changes the way we look at networks
-Best practices customers should employ moving forward with cloud migration
-What happens behind the scenes of SteelConnect’s one-click button

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

This article explains how to create forms/units independent of other forms/units object names in a delphi project. Have you ever created a form for user input in a Delphi project and then had the need to have that same form in a other Delphi proj…
Hello everybody This Article will show you how to validate number with TEdit control, What's the TEdit control? TEdit is a standard Windows edit control on a form, it allows to user to write, read and copy/paste single line of text. Usua…
There are cases when e.g. an IT administrator wants to have full access and view into selected mailboxes on Exchange server, directly from his own email account in Outlook or Outlook Web Access. This proves useful when for example administrator want…
Michael from AdRem Software outlines event notifications and Automatic Corrective Actions in network monitoring. Automatic Corrective Actions are scripts, which can automatically run upon discovery of a certain undesirable condition in your network.…
Suggested Courses
Course of the Month10 days, 23 hours left to enroll

628 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question