• If the exception process is declared in the project initialization code, it is valid for any error that occurs in the project.
• If the exception process is declared in the declaration code of the global variables of a window, page or report, it is valid for any error that occurs in the window, in the page, in a window control, in a page control or in a procedure local to the window or to the page. This exception process is not valid anymore when the window or the page is closed.
• If the exception process is declared in any process, it is valid for any error that occurs in this process. This exception process will not be valid anymore once the process is completed. Therefore, an exception process declared in the click code of a button will only be valid in this process and in all the procedures called from this process.

Remark:

• The mechanism of general exceptions is not available.. Only the specific exceptions (WHEN EXCEPTION IN) are available. For more details, see Management of specific exceptions.
• You can also use ExceptionChangeParameter with the epExecuteProcedureOverall constant in the project "Initialization" event.

Declaring the processes of general exceptions in the same process

• In the <Code1> no exception handling is active unless an exception procedure has been defined in the calling code (in the current window, page or project).
• In <Code 2>: the active exception process is <Exception Process 1>.
• At <Code 3>: active exception handling is <Traitement Exception 2>.

Declaring the exception processes in different processes

• exception process A declared in the initialization code of a project,
• exception process B declared in the declaration code of global variables of a window or page.

Nesting exception processes in different processes: managing the exception via a higher level

// Project initialization code
WHEN EXCEPTION
	// Stop the application
	EndProgram()
END

// Global procedure ControlValue
// Returns the value of the control or "" if the control does not exist
PROCEDURE ControlValue(ControlName)
WHEN EXCEPTION
	// For the UnknownControl error, "" is returned
	IF ExceptionInfo(errCode) = UnknownControl THEN RETURN ""
	// For another error, the error manager of the project is called
	EXCEPTION
END

An exception process can only be used once

For example A general exception has been declared at both window and project level.
A first programming error occurs in the window. This error is processed by the exception process of the window.
A second error occurs in the window. This error is processed by the exception process of the project.

For example A general exception has been declared at page and project level.
A first programming error occurs in the page. This error is processed by the exception process of the page.
A second error occurs in the page. This error is processed by the exception process of the project.

Quality of WLanguage code for processing the exception

Quality of the code following an exception process

// Exception process
WHEN EXCEPTION
	// Process to perform if an exception occurs
	Trace("Error")
END
// Programming error: field Champ1 does not exist
{"Control1"}..Value = 5

• Make sure that the problem is corrected and that it will not happen again.
• Use the RETURN and RESULT keywords to exit from the current process.
• Use SetFocusAndReturnToUserInput to give control back to the user.
  This feature is not available.
• Use EndProgram to close the application.

• FOR
• LOOP
• WHILE

Exception process and component

Exception process and threads

• in the main thread,
• in a secondary thread started by ThreadExecute.