Converter limitations

Converter limitations

• blah569

  Doug,

  In his original post I believe he mentioned that he didn't want to create an instance for each permutation of property settings. My solution would allow him to avoid creating any instance in XAML. I like your idea of using the ConverterParameter. Perhaps one could use the technique I presented, but pass the converter config values in the ConverterParameter instead of making a separate class with an attached property, etc. The converter could configure its properties when it's used based the values in the ConverterParameter value. Very interesting...

  
  
  

• KDX

  Nick,

  Setting an attribute in XAML does not create the property in the class (i.e. the C# code). You mentioned in your first post on this thread that the converter class has multiple properties which can be configured. Those are the properties I was suggesting you set. If you set a property in XAML, that property must exist in the real class first.

  
  
  

• fabianus

  1. Doh! - I knew that, sorry

  2. Still a little fuzzy on this part.

  a) Is this declaring the existence of the property to the XAML compiler

  b) Do I have to implement the property on the converter object to back it up

  c) Why the x:key name

  d) Does this affect all instances of the converter object

  e) Compile error with the syntax given

  <MyNameSpace:MyConverter x:Key="conv1" Property="Something" />

  Error 5 The property 'Property' does not exist in XML namespace 'http://schemas.microsoft.com/winfx/2006/xaml/presentation'.

  3. Ok

  4.

  
  
  

• Ayhan Yerli &amp;#40;TR-NL&amp;#41;

  Understood, it just wasn't clear at first glance what was assumed to exist (or to be understood by me).

  Ok, so everyone gets a helpful post mark.

  Thanks again.

  
  
  

• Dinesh Patel

  This might be overkill, but you could make a class which exposes an attached property. On each TextBox in the XAML you set the attached property. The property is set to something like this MyAttachedProperty="Attribute1=OptionA, Attribute2=OptionB, Attribute3=OptionC". In the class which exposes the attached property, you have logic which parses that input value and configures a ValueConverter to use the specified options/settings. It then would retrieve a reference to the TextBox's Text property Binding and set its Converter property to that configured ValueConverter.
  
  

• su45937

  Thanks for the response folks:

  I don't understand the XMAL here.

  1) MyConverter is not a valid tag, so it won't compile like this.

  2) Does Property="Something" create a property on the converter

  3) if 2, how do I set the property in XAML

  4) How do I designate data type for the property

  
  
  

• toben888

  Am I limited to one attached property
  
  

• Mazmo

  No. If you have a definite number of properties on the Converter and don't intend on reusing the converter factory, then having separate attached properties for each Converter property would be the way to go. I guess I always think in terms of generalized solutions! :)
  
  

• smileyke

  You can set any properties you want on the converter when you instantiate it:

  eg.

  <MyConverter x:Key="conv1" Property="Something" />

  <MyConverter x:Key="conv2" Property="Something Else" />

  Or you can use the ConverterParameter in the binding - but this is restricted to one value.

  {Binding Converter={StaticResource ...}, ConverterParameter=Something}

  - Doug

  
  

• Ian_E

  e. MyNameSpace:MyConverter.Property
  
  

• sunny123

  1. you should include namsspace <local:MyConverter.../>

  2. yes

  3. you can set it like you set any property <local:MyConverter myproperty=""/>

  
  
  

• Girishbs

  Ok, I think my brain just finally grocked all this, the partial XAML threw me off a bit.

  I implemented a property (DigitsOfPrecision) on my converter class (MyDoubleConverter).

  The following declaration goes in the Windows.Resources section.

  <MyNamespace:MyDoubleConverter x:Key="DoubleConverter" MyNamespace:MyDoubleConverter.DigitsOfPrecision="2"/>

  Then, my binding just references the object "DoubleConverter" as it did before.

  <Binding Path="Value" Source="{StaticResource ExposureTime}" Converter="{StaticResource DoubleConverter}" UpdateSourceTrigger="PropertyChanged"/>

  This works.

  Thanks for the communal effort

  
  
  
• Converter limitations