I have a requirement where I need to have a “type safe” way of accessing property names, without actually instantiating an object to get to the property. To give an example, consider a method that takes as arguments a list of IMyObject and a string that represents a property name (a property that exists in IMyObject).
The methods implementation will take the list and access all the objects in the list using the property name passed… for some reason or another, we won’t dwell on that!!
Now, I know that you can do this using an instantiated object, something like …
Dim x as MyObject = nothing
Dim prop As PropertyInfo = PropHelper.GetProperty(Of MyObject)(Function() x.MyProperty)
Where my helper method uses reflection to get the name of the property as a string – there are numerous examples of this flying around on the web!
But I don’t want to have to create this pointless object, I just want to do something like MyObject.MyProperty! Reflection allows you to iterate through a types properties and methods without declaring an object of that type… but I want to access a specific property and retrieve the string version of its name without iteration and without declaring an object of that type!
The main point here is that although I am trying to get the property name as a string… this is done at run time… at compile time, I want this to be type safe so if someone changes the property name, the compilation will break.
Can anyone help in this quest!?!
You may be able to pass the property in as a simple lamdba expression, and take it in the method as an expression tree. You should be able to analyze the expression tree to get the string name of the property, but it the lambda expression will fail to compile if the property name changes. Check out this page for more details:
http://msdn.microsoft.com/en-us/library/bb397951.aspx