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Creating Property Procedures

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Public module-level variables in a class module function as properties of an object. However, they're not very sophisticated. If you must run code 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: Property Get, Property Let, and Property Set procedures. The Property Get procedure returns the current value of a property, whereas the Property Let procedure sets the value. The Property Set procedure assigns an object to an object property.

To create a read-write property, you must 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 Property Let procedure to set the value and a Property Get procedure to retrieve it. If the property stores and returns a reference to an object, you use the Property Set procedure to store the reference and the Property Get procedure to return it.

In addition, you can create read-only, write-only, and write-once properties. The following table outlines which property procedures you must have for each type.

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

See Also

Why Build Your Own Objects? | Creating Scalar Properties | Creating Object Properties | Basic Class Concepts | Creating Events and Event Procedures | Extending Objects Through Interfaces | Designing Object Models | Creating Custom Objects for Web Pages

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