The foreach identifier and closures

Question

In the two following snippets, is the first one safe or must you do the second one?

By safe I mean is each thread guaranteed to call the method on the Foo from the s

Answer 1

Your need to use option 2, creating a closure around a changing variable will use the value of the variable when the variable is used and not at closure creation time.

The implementation of anonymous methods in C# and its consequences (part 1)

The implementation of anonymous methods in C# and its consequences (part 2)

The implementation of anonymous methods in C# and its consequences (part 3)

Edit: to make it clear, in C# closures are "lexical closures" meaning they don't capture a variable's value but the variable itself. That means that when creating a closure to a changing variable the closure is actually a reference to the variable not a copy of it's value.

Edit2: added links to all blog posts if anyone is interested in reading about compiler internals.