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{Long_operation}



CLASS {Long_operation}
, UNTESTED, DESTRUCTORS, NATIVE:



 The form class to show it automatically when a long operation is detected.
 In the AL-IV, on each loop iteration (in all the FOR statements in the
 entire code) the global counter is decreased and if it was zeroed, a stub
 function is called (usually on each 65535th time) to reinitialize that counter
 and to call the system function which checks if a long operation occur.
 A long operation is detected in case when your code did not end a method
 called to handle the last event for a long time period (more then 1 second).
 It is also possible to provide a progress of long operations in your code
 which will be displayed on this form. To do so, just use a form method
 Long_operation, which returns an instance on the {Long_operation}
 associated with the form (or creates it and rerturns if it was not yet
 created). And, use its methods like Set_progress, Set_description etc. to
 specify such information during a long operation. Also, it is possible to
 call periodically the Indicate method to inform the {Long_operation} form
 that your code still working and it it is not necessary to detect a long
 operation (this just resets time point from which the 1 second period is
 starting).


 But the main purpose of the (non-modal) dialog is to allow to user to pause
 or cancel the operation detected without crashing entire application.


 There is a compiler option to disable such checks on each iteration and to
 show the long operation dialog. It is better in such case to specify a path
 to a dummy implementation of the {Long_operation} form to minimize dependances.
 It is also possible to make your own implementation of a long operation
 detection function for your own purposes.





IMPORT : 
{AL4_form}
 .


BASE CLASS 
{Form} .



STR 
Sender_alias
 , INIT







--------------------------------------------------------- 'visual controls'








METHOD 
Set_description

(
STR 
D|escription_text
)






 Set a description for a long operation planned to be executed. It is also
 possible to change the description at any time later.









METHOD 
Set_stage|_details

(
STR 
D|etails_on_current_stage
)






 Set a description for a long operation stage of the operation).









METHOD 
Set_progress|_0_TO_100

(
REAL 
P|rogress_value
)






 Set a progress for a long operation (this is optional, if there were no call
 of thatg method, the progress is just looping).





BOOL 
Paused|_until_button_pressed_again
 , READ


 TRUE, if the long operation was paused.






BOOL 
Cancelled|_operation
 , READ


 TRUE, if the operation was cancelled (by the user).












METHOD 
Indicate|_activity

(
BOOL 
Proc|ess_messages
)
 , CALLBACK






 Use this method to restart counting 1 second before deciding that your code
 is no more responding. Pass TRUE as the parameter to allow processing other
 events on the form. This makes your application more resposibility without
 using threading ({Thread} class).





BOOL 
Finished|_operation






END