RDC00104 — Implicit ByRef modifier

Severity: Information · Family: RDC (Rubberduck Core analyzers) · Raised by: ImplicitByRefModifierAnalyzer

A parameter states neither ByRef nor ByVal.

A parameter that states no mechanism is passed by reference (MS-VBAL §5.3.1.5 Parameter Lists): the procedure can change the variable of the caller, which is rarely what a reader of the signature expects, and is not visible in it. The diagnostic is an opinion of the analyzer and not a condition of the language: both are legal VBA.

Two parameters are not reported, because they cannot state it: a ParamArray, and the value parameter of a property Let or Set, which is always passed by value (MS-VBAL §5.3.1.7 Property Declarations).

That a parameter states no mechanism is a fact of the way it is written: the analyzer reads it off the syntax tree. It is a suggestion because writing the keyword does not change what the procedure does.

How it is raised

Situation	Example	Resolution
A parameter of a procedure, an event or a `Declare` states no `ByRef` or `ByVal`.	`Sub Work(total As Long)`	Write `ByRef` if the procedure is meant to change the argument, and `ByVal` otherwise.

Table of Contents

RDC00104 — Implicit ByRef modifier

How it is raised

See also