Modifying list inside foreach loop

Question

I have a construction similar to this (but a lot more complicated):

var list = new List();

// .. populate list ..

foreach(var item i         


        

Answer 1

It's hard to offer useful advice without knowing what kinds of edits are being made. The pattern that I've found is has the most general-purpose value, though, to just construct a new list.

For example, if you need to look at each item and decide between removing it, leaving it as-is, or inserting items after it, you could use a pattern like this:

IEnumerable butcherTheList(IEnumerable input)
{
    foreach (string current in input)
    {
        if(case1(current))  
        {
            yield return current;
        }
        else if(case2(current))
        {
            yield return current;
            yield return someFunc(current);
        }
        // default behavior is to yield nothing, effectively removing the item
    }
}

List newList = butcherTheList(input).ToList();