How to compile a c# Lambda expression to a System.Linq.Expression.

[Colin Han]

Hi, all,
If I write follow code in c# method. The IDE will compile it to a complex construct method of System.Linq.Expression.
Expression<Func<int>> ex = () => 10;
will be compile to:
Expression<Func<int>> ex = Expression.Lambda<Func<int>> (Expression.Literal(10))
It is so smart. I can travel in this expression tree. I can do some smart abilities on this design.

Now, I want write a console application. If user input follow string from console,
() => 10
I want make a LambdaExpression object and execute it in my context.
I can use CodeDom to compile some c# code to a dynamic assembly. But I have not found a utility to compile c# code to an expression object.

How to compile a c# Lambda expression to a Expression object? Help me. Thanks.

 

[Marc Gravell]

Well, it isn't that simple... you'd need to parse that yourself and
build the Expression by hand, or use the "dynamic LINQ" sample (which
does much of that):

http://weblogs.asp.net/scottgu/arch...t-1-using-the-linq-dynamic-query-library.aspx

An alternative would be to use the CSharpCodeProvider to compile it *as*
C# (with suitable wrappers), and load the generated assembly on the fly;
not pretty.

Marc

 

[Colin Han]

Thanks Marc.

I had download the sample. It look is so cool. Thank you vary much.