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AppSourceCop Error AS0021

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An argument in an event attribute cannot be changed to false.

Description

An argument in an event attribute cannot be changed to false. This is not allowed because it may break dependent extensions that have subscribed to this event.

Remarks

This rule verifies that events that are available from other extensions such as Business type events or Integration type events do not stop exposing their sender or their global variables.

This does not apply to Internal type events as they are not exposed to dependent extensions.

Code examples triggering the rule

Example 1 - A business type event stops exposing its sender

Version 1.0 of the extension:

codeunit 50100 MyCodeunit
{
    [BusinessEvent(true)]
    procedure MyEvent()
    begin
    end;
}

Version 2.0 of the extension:

codeunit 50100 MyCodeunit
{
    [BusinessEvent(false)]
    procedure MyEvent()
    begin
    end;
}

In the newer version, the sender exposed by MyEvent is not accessible to subscribers anymore. If a dependent extension relies on it, this will lead to a compilation error similar to The member referenced by event subscriber 'MyProcedure' parameter 'sender' is not found (AL0282).

For example, the following extension compiles when depending on version 1.0, but fails to compile with version 2.0:

codeunit 50120 AnotherCodeunit
{
    [EventSubscriber(ObjectType::Codeunit, Codeunit::MyCodeunit, 'MyEvent', '', true, true)]
    local procedure MyProcedure(sender: Codeunit MyCodeunit)
    begin
        // Subscriber logic
    end;
}

Example 2 - An integration type event stops exposing global variables

Version 1.0 of the extension:

codeunit 50100 MyCodeunit
{
    [IntegrationEvent(true, true)]
    procedure MyEvent()
    begin
    end;

    var
        myGlobalVariable: Integer;
}

Version 2.0 of the extension:

codeunit 50100 MyCodeunit
{
    [IntegrationEvent(true, false)]
    procedure MyEvent()
    begin
    end;

    var
        myGlobalVariable: Integer;
}

In the newer version, the global variables exposed by MyEvent are not accessible to subscribers anymore. If a dependent extension relies on global variables, this will lead to a compilation error similar to The member referenced by event subscriber 'MyProcedure' parameter 'myGlobalVariable' is not found (AL0282).

For example, the following extension compiles when depending on version 1.0, but fails to compile with version 2.0:

codeunit 50120 AnotherCodeunit
{
    [EventSubscriber(ObjectType::Codeunit, Codeunit::MyCodeunit, 'MyEvent', '', true, true)]
    local procedure MyProcedure(myGlobalVariable: Integer)
    begin
        // Subscriber logic
    end;
}

Code examples not triggering the rule

Example 1 - An event does not change over time

Version 1.0 of the extension:

codeunit 50100 MyCodeunit
{
    [BusinessEvent(false)]
    procedure MyEvent()
    begin
    end;
}

Version 2.0 of the extension:

codeunit 50100 MyCodeunit
{
    [BusinessEvent(false)]
    procedure MyEvent()
    begin
    end;
}

The event remains the same from one version to the other.

Example 2 - An event starts exposing its sender

Version 1.0 of the extension:

codeunit 50100 MyCodeunit
{
    [BusinessEvent(false)]
    procedure MyEvent()
    begin
    end;
}

Version 2.0 of the extension:

codeunit 50100 MyCodeunit
{
    [BusinessEvent(true)]
    procedure MyEvent()
    begin
    end;
}

In the newer version of the extension, the sender becomes exposed through the business type event.

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