Flags parameters that are passed by reference (ByRef), but could be passed by value (ByVal).

Inspection type: MaintainabilityAndReadabilityIssues

Default severity: Suggestion


Explicitly specifying a ByVal modifier on a parameter makes the intent explicit: this parameter is not meant to be assigned. In contrast, a parameter that is passed by reference (implicitly, or explicitly ByRef) makes it ambiguous from the calling code's standpoint, whether the procedure might re-assign these ByRef values and introduce a bug


For performance reasons, this inspection will not flag a parameter that is passed as an argument to a procedure that also accepts it ByRef.


The following quick-fixes are available for this inspection:

  • IgnoreOnce: Adds an '@Ignore annotation to ignore a specific inspection result. Applicable to all inspections whose results can be annotated in a module.
  • IgnoreInModule: Adds an '@IgnoreModule annotation to ignore a inspection results for a specific inspection inside a whole module. Applicable to all inspections whose results can be annotated in a module.
  • PassParameterByValue: Modifies a parameter to be passed by value.


Each example is a self-contained MCVE showing the feature in a single specific scenario.

Standard Module
Named Module1 by default, these are general-purpose standard procedural modules.
Class Module
Named Class1 by default, these modules define the default interface for an object of that type.
Predeclared Class
A class module with its VB_PredeclaredId attribute set to True (with or without a @PredeclaredId annotation).
Interface Module
Abstract interfaces are class modules (with or without an @Interface annotation) whose default interface is not a class type intended to be instantiated.
UserForm Module
A predeclared class with a design-time visual designer using the MSForms UI framework.
Document Module
Owned by the host application, these class modules belong to the host document and may handle various events fired by the host application.

The following code should trigger this inspection:


Public Sub DoSomething(ByVal foo As Long, bar As Long)
    Debug.Print foo, bar
End Sub

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