Using partial classes

Question

Is there any overhead using partial classes in case of memory, performance etc?

If we create a partial class can we identify whether the class was partial or not using reflector??

Answer 1

No. They are compiled to the same IL as if they weren't partial. It's a purely compile-time thing - the CLR doesn't even know that they were ever partial.

Note that with partial methods introduced into C# 3, the method doesn't even get emitted in the IL unless it's implemented in one of the files. Both the calls and the declaration get stripped out by the compiler.

It's possible that it'll slow down the compiler an imperceptible fraction of a millisecond, of course :)

Answer 2

No, all class files will get consolidated at compile time.

Here's the msdn article on partial types.

Each source file contains a section of the type or method definition, and all parts are combined when the application is compiled.