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Property-Bindings

Idea is taken from https://github.com/praeclarum/Bind. Original code suffered from memory leaks, performance issues and not supporting property paths with NULL values.

This project aims to support property binding similar to WPF bindings which support property paths

Binding.Create(() => left.Property1.Property2.Property3.Name, () => right.Property1.Name);

where any property in this path can be null. Binding will be created even if a property in the path is null but won't trigger updates until all properties Property1, Property2, Property3 have non-null value. If you don't care about properties paths and nulls you don't need this library, because it won't require expression trees and reflection which has huge overhead.

Usage

See unit tests

Performance

Creating the binding is the slowest part, because it uses reflection and compilation of expression trees

for (int i = 0; i < 1000; i++)
{
    bind = Binding.Create(() => left.Name, () => right.Name);
}

For 1000 Binding.Create it takes 370ms on Intel i7-4710HQ. This can get slower if you have long property paths like this, because more expressions will be compiled

Binding.Create(() => left.Property1.Property2.Property3.Name, () => right.Property1.Property2.Property3.Name);

Property updates are fast enough, just 2x slower that manual property updates.

string[] values = new string[1000];
var binding = Binding.Create(() => left.Name, () => right.Name);
...

// this is 1x
for (int i = 0; i < 1000; i++)
{
   left.Name = values[i];
   right.Name = left.Name;
}

// this is 2x
for (int i = 0; i < 1000; i++)
{
    left.Name = values[i]; // this will update right.Name
}

Version 1.0

  • Optimization - Use FastExpressionCompiler to speed up Lambda.Compile
  • Optimization - Do not use Lambda.Compile for Constant Expressions

Version 0.2

  • You can now have working bindings if there is null value in property path. Example: Binding.Create(() => instance1.Test.Name, () => instance2.Test.Name) - that will work even if intance1.Test is null

Version 0.1

  • New syntax - PropertyBinding.Create(() => obj1.Property1.Property2.Name, () => obj2.Property1.Property2.Name)
  • Use of ConditionalWeakTable to hold WeakReferences instead of hard references - this way if your binding instance go out of scope the left and the right side instances will be eligble for GC and they won't leak
  • Ability to bind with property path PropertyBinding.Create(() => obj1.Property1.Property2.Name, () => obj2.Property1.Property2.Name) where some properties in the path can be null. Original code doens't support that.
  • Bug fix for memory leak when property subscriptions was not removed from the static dictionary on unsubscribe
  • Added Unit tests