Are value converters instantiated per-binding in WPF?

Question

Is a separate WPF value converter object instantiated for each binding that a particular value converter class is used in?

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I am trying to create a two-way bit-to-boolean value converter. I would like to be able to bind a bool property (such as IsChecked) to a bit in a value type (like a ushort). I'm using the converter's parameter arguments to specify the bit. Implementing the ConvertBack() method is easy, but Convert() is little trickier.

In Convert() I need to know what the value of the entire ushort is so I can toggle just the single bit I am interested in. I was thinking of just using a member variable in my value converter class to temporarily store this whenever ConvertBack() is called, thus leading to the above question: does each binding get its own value converter instance?

Answer 1

Create a constructor and destructor in your converter and set breakpoints within to tell for sure. I just created a simple example and it looks like only one converter was created for my multiple viewmodels that were using the constructor

Answer 2

If you use a converter defined in your resources, it will be shared amongst your properties.

If you need unique converters: If you create a specific converter for a property, however, it will not be shared. Either option is workable. You can even use multiple converters (of the same type, with different keys) in your resources, which will create unique instances.