Using parameter "Cancel" (UsingCancelParameter)

Type	Scope	Severity	Activated by default	Minutes to fix	Tags
Code smell	BSL OS	Major	Yes	10	standard badpractice

Description

In event handlers of object's modules, record sets, forms and etc. using parameter "Cancel" (for example BeforeWrite and etc.) it should not be assigned value "false".
This is due to the fact, that in code of event handlers the parameter "Cancel" can be set in several consecutive checks (or in several subscriptions on the same event). In this case, by the time the next check is performed, the Cancel parameter may already contain the True value, and you can erroneously reset it back to False.
In addition, with configuration improvements, the number of these checks may increase.

Examples

Incorrect

Procedure BeforeWrite(Cancel)
  ...
  Cancel = CheckName();
  ...
EndProcedure

Correct

Procedure BeforeWrite(Cancel)
  ...
  If CheckName() Then
   Cancel = True;
  EndIf;
  ...
EndProcedure

or

Cancel = Cancel or CheckName();

Sources

• Standart: Working with the "Cancel" option in event handlers (RU)

Snippets

Diagnostic ignorance in code

// BSLLS:UsingCancelParameter-off
// BSLLS:UsingCancelParameter-on

Parameter for config

"UsingCancelParameter": false