The Property Dependency Framework (PDFx) is a lightweight library that allows you to capture the inherent relationship among the properties of your classes in a declarative manner. It is common in applications to have properties whose values depend upon the values of other properties. These properties need to be reevaluated when a change occurs in the properties on which they depend. For example, if “A” depends on “B” and “C”, we need to reevaluate the value of A whenever either B or C changes. Furthermore, B and C may not even be direct properties of the same class as that in which A exists. Instead, they may be properties of another class, or even properties of the items within a collection.

In large applications, complex chains of such dependencies can exist. Although C# gives us the INotifyPropertyChanged construct to send out a change notification (typically to UI elements), no framework to our knowledge has allowed the network of dependencies to be specified in a straightforward manner, with the proper change notifications issued automatically. The PDFx framework allows the dependencies of properties to be specified declaratively, building from them an internal network of dependencies for you. Changes to any property in the network are then propagated automatically and efficiently.

The PDFx framework establishes a simple pattern for capturing the relationships of data in applications, and removes tremendous amounts of “plumbing”. It also helps clarify and enhance the role of the View Model within MVVM, reducing the scattering of business logic throughout value converters. Once you’ve made use of PDFx, you will likely wonder how the gap it fills has gone unaddressed for so long.

Last edited May 9, 2013 at 6:03 PM by KevinStumpf, version 1


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