RDC00407 — Unmatched event handler

Severity: Hint · Family: RDC (Rubberduck Core analyzers) · Raised by: UnmatchedEventHandlerAnalyzer

A procedure of a form is named as the handler of an event of one of its controls, and does not match the event: nothing ever calls it.

A procedure named ControlName_EventName handles that event of the form's control (TextBox1_Change handles the Change event of TextBox1), when it is a Sub that takes the event's parameters. One that is a Function, or that takes other parameters, is not called when the event is raised. MS-VBA compiles it all the same, and says nothing about it (recorded in Excel): it is dead code. The editor shows it the way it shows code that cannot be reached.

A Private procedure like that which the form's own code calls is not dead, and is not reported: it is an ordinary procedure, with a misleading name. A Public one is not reported either, because code elsewhere in the project could call it through the form.

How it is raised

Situation	Example, for a form with a `TextBox1`	Resolution
A handler of a control's event, with parameters the event does not have.	`Private Sub TextBox1_Change(ByVal Value As Long)`	Give it the event's parameters (`Private Sub TextBox1_Change()`), or remove it.
A handler of a control's event declared as a `Function`.	`Private Function TextBox1_Change() As Long`	Declare it a `Sub`, or remove it.

The quickest way to write a handler that matches is to let the editor write it: pick the control and the event, and the procedure is declared with the event's parameters.

Notes

For a WithEvents variable that the code declares, rather than a form's control, a handler that does not match its event is a compile error, VBC09326 Invalid event handler, in MS-VBA as in RD-VBA.

Table of Contents

RDC00407 — Unmatched event handler

How it is raised

Notes

See also