Creating Property Procedures

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As mentioned previously, public module-level variables in a class module function as properties of an object. However, they're not very sophisticated. If you need to run code in order to set or return a property's value, or you want to make a property read-only, you can create a Property procedure. There are three types of Property procedures: PropertyGet, PropertyLet, and PropertySet procedures. The PropertyGet procedure returns the current value of a property, whereas the PropertyLet procedure sets the value. The PropertySet procedure assigns an object to an object property.

To create a read-write property, you need to include a pair of Property procedures in the class module. Both procedures must have the same name. If the property stores and returns a scalar value, such as a numeric, text, or date value, you use a PropertyLet procedure to set the value and a PropertyGet procedure to retrieve it. If the property stores and returns a reference to an object, you use the PropertySet procedure to store the reference and the PropertyGet procedure to return it.

You can also create read-only, write-only, and write-once properties. The following table outlines which property procedures you need for each type.

Type of property	Procedures needed
Read-write, scalar	Property Let, Property Get
Read-write, object	Property Set, Property Get
Read-only, scalar	Property Get
Read-only, object	Property Get
Write-only, scalar	Property Let
Write-once, scalar	Property Let, including code to determine whether property has been set previously, Property Get
Write-once, object	Property Set, including code to determine whether object property has been set previously, Property Get