Creating an Intellisense compatible enum-based Dependency Property

Actually, this post has a way too fancy title , because in fact I will merely show that enum-based dependency properties are IntelliSense compatible “out-of-the-box”. (by the way, if you know all about dependcy properties: simply read the line in bold and you’ll know all there is to know).

When creating a (WP7/SL/WPF) usercontrol, one often ends up creating one more dependency properties (DP). Most of the times you only want a discrete set of possible values that can be assigned to the DP. The logical choice then of course is to have an enum-based DP.

Now, for the Intellisense to work it is important that you define the enum type OUTSIDE the usercontrols class. For example, suppose we have define the following enum:

public enum GraphTypes {Default, Point, Line}

Now, all that remains is to add a DP that uses this enum (remember that you can use the ‘dependencyproperty’ snippet that comes with VS):

        public static readonly DependencyProperty GraphTypeProperty =
            DependencyProperty.Register("GraphType", typeof (GraphTypes), typeof (GraphControl), new PropertyMetadata(GraphTypes.Default));

        public GraphTypes GraphType
            get { return (GraphTypes) GetValue(GraphTypeProperty); }
            set { SetValue(GraphTypeProperty, value); }

Once you now add the usercontrol elsewhere in your xaml-code, IntelliSense will happily show what values can be assigned to the DP:

There we go. That’s all there was too it.

Next post I’ll show how to create a WP7 user control to plot graphs using data binding. Consider some of the code here a sneak preview.


Using enum flags to write filters in Linq

Here’s the premise. Suppose we have a cookbook that contains all possible recipes with their names and needed ingredients. Using Linq it should be easy to query the cookbook and, for example, only show those recipes you can make given one or more ingredients you have at your house. My solution is a) extremely nice or b) very strange, bloated and way wrong. I leave it up to you and make sure to message me if you have a much nicer solution…because franky, I’m not a big fan of what follows (I have the itching sensation that using the correct binary logic I can solve this problem much easier…).

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