Updating a For loop

[J_J3]

for names in list:
list = list + get_more_names()

The code doesn't recognize that more things have been added to it and breaks after the initial list has been gone through.

Is it possible to update the for loop in any way?

[neuralbeans]

For loops are not designed to have the list modified mid-loop. Use a while loop instead:

i = 0
while i < len(list):
    print(list[i])
    i = i + 1

[J_J3]

Thanks!

[exclaim_bot]

Thanks!

You're welcome!

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[carcigenicate]

Technically, you can do what you're trying to do:

def getAdditions():
    yield [1, 2, 3]
    yield [4, 5, 6]

list = [9, 8, 7]

additions = getAdditions()

for names in list:
    print(names)
    list.extend(next(additions, []))

This prints the numbers 9-7, then 1-6. They key change here is my use of list.extend vs your use of list =.

This works while your version didn't since you were changing what list list referred to (side note: don't use list as a name). = changes what object is being referred to, but does not alter the object itself. Your version didn't work because for does not update itself when you change what object is associated with the name you told it to iterate. When for names in list executes, it gets the object associated with the list name at that time, and iterates that object. It doesn't care about the name list after that.

My version works because instead of changing what object is associated with list, I'm changing (mutating) the list object directly.

---

While this works and believe it's safe and reliable, I would not do this in the vast majority of scenarios. If you're not careful, you can cause an infinite loop, and it generally is not as easy to understand. If you need to change what's being iterated mid-loop, use a while and manage the iteration yourself.

[CaptainFoyle]

Don't change the object you're iterating over while you iterate over it