How to use CallByName function in VBA?

The CallByName function in VBA (Visual Basic for Applications) provides a way to call a property, method, or function on an object dynamically, using a string that contains the name of the property, method, or function. This is particularly useful for situations where the specific property or method to be called is not known until runtime. The syntax of the CallByName function is:

VBA

CallByName(Object, ProcName, CallType, Arguments...)

Object: The object on which the property, method, or function is being called.
ProcName: A string expression that contains the name of the property, method, or function on the object.
CallType: A constant that specifies the type of procedure being called. It can be one of the following: VbGet, VbLet, VbMethod, VbSet.
- VbGet is used to retrieve the value of a property.
- VbLet and VbSet are used to assign a value to a property (with VbLet for value properties and VbSet for object properties).
- VbMethod is used to call a method.
Arguments…: Optional parameters that are passed to the property, method, or function being called.

Example Usage

Suppose you have a class named MyClass with a method ShowMessage and a property MyProperty. Here’s how you might use CallByName:

VBA

Dim obj As MyClass
Set obj = New MyClass

' Call a method
CallByName obj, "ShowMessage", VbMethod

' Set a property
CallByName obj, "MyProperty", VbLet, "New Value"

' Get a property
Dim propValue As String
propValue = CallByName(obj, "MyProperty", VbGet)

In this example:

The ShowMessage method of obj (an instance of MyClass) is called.
The MyProperty property of obj is set to “New Value”.
The value of MyProperty is retrieved and stored in propValue.

Points to Remember

CallByName is very useful for calling methods or properties dynamically when the exact names are not known until runtime.
It’s important to ensure that the ProcName string matches the actual name of the method or property on the object. Mismatches will result in runtime errors.
This function is commonly used in situations where the code needs to be flexible and able to work with different objects or classes.

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