v8-code-style/bundles/com.e1c.v8codestyle.bsl/markdown/event-heandler-boolean-param.md

Use event handler boolean parameter

In event handlers of object modules, record sets, forms, etc., containing the Cancel parameter (OnWrite, FillCheckProcessing, DescriptionStartListChoice, etc.), you should not set the value False to this parameter. This requirement is due to the fact that, usually, in the code of event handlers, the Cancel parameter can be set in several consecutive checks at once (or in several event subscriptions to the same event). In this case, by the time the next check is performed, the Cancel parameter may already contain the value True in advance, and you can mistakenly reset it back to False. In addition, the number of these checks may increase when the configuration is customizing during the integration.

Noncompliant Code Example

Procedure ОбработкаПроверкиЗаполнения(Cancel, CheckingAttributes) 
  ... 
  Cancel = IsFilleCheckError(); 
  ... 
ProcedueEnd

Compliant Solution

Procedure FillCheckProcessing(Cancel, CheckingAttributes) 
  . . . 
  if IsFilleCheckError() The 
    Cancel = Истина;
  EndIf; 
  ... 
ProcedueEnd 

Or

Cancel = Cancel Or IsFilleCheckError(); 

See