Call a method in the declaration of a foreach

Question

I have a foreach which calls a method to get its collection.

 foreach(var item in GetItemDetails(item))
 {
 }

Visual studio doesn't complain about this, nor does Resharper, however, before I continue to use this approach, I want to reach out and check if it is a recommended approach.

Answer 1

There's nothing wrong with that. The method will only be evaluated once.

It is basically:

using(var iter = GetItemDetails(item).GetEnumerator())
{
    while(iter.MoveNext()
    {
        var item = iter.Current;
        // ...
    }
}

Answer 2

There's nothing wrong with it.

Just two suggestions:

• If what you will put in the loop can written as a method for single items, which would make it re-usable, I would also consider the List.ForEach(...); method. Info: http://msdn.microsoft.com/en-us/library/bwabdf9z%28v=vs.110%29.aspx

• In case you'd be really after performance (which may happen even in C#), the for loop is usually the fastest, though less readable as less concise code: Info: In .NET, which loop runs faster, 'for' or 'foreach'?