Question

From what I can see, the ForEach method is available only for the List class.

Why is that? I can see no reason for ForEach not to be available to any class implementing the IEnumerable/IEnumerator interfaces, and this is a really useful method if you need to perform a small action (1 line is more readable than 1 line + 2 boilerplate foreach syntax…).

Update: I’ll clarify my question. There are perfectly valid reasons for including ForEach in sequences. There are perfectly good reasons for not including ForEachin all sequences.

But I cannot understand why would ForEach be included in just some of the sequences.

Answer 1

See Eric Lippert’s post: “foreach” vs “ForEach”

A number of people have asked me why
there is no Microsoft-provided
“ForEach” sequence operator extension
method. The List class has such a
method already of course, but there’s
no reason why such a method could not
be created as an extension method for
all sequences.

…

But we can go a bit deeper here. I am
philosophically opposed to providing
such a method, for two reasons.

…

The first reason is that doing so
violates the functional programming
principles that all the other sequence
operators are based upon. Clearly the
sole purpose of a call to this method
is to cause side effects.

…

The second reason is that doing so
adds zero new representational power
to the language.

…

Well, the VS Languages team does not
have any influence on what goes into
List. I personally find the
“ForEach” method on List
philosophically troubling for all the
same reasons that I would find an
extension method on IEnumerable
troubling. (And the VSL team does
control that.) The one mitigating
factor is that List is clearly
designed to be a mutable,
not-side-effect-free data structure,
so using expressions that mutate it
seems slightly less bad. — Eric