ExitStack

Learn dynamic context management with ExitStack.

ExitStack

ExitStack dynamically manages multiple context managers. It is ideal when the number is not known in advance:

from contextlib import ExitStack

with ExitStack() as stack:
    stack.callback(print, "bitti")
    print("içeride")
# bitti

Here stack.callback(print, "bitti") schedules a print("bitti") call at block end. ExitStack runs all callbacks in reverse order.

This is a flexible tool for dynamic cleanup.

callback and enter_context

ExitStack offers two main methods. callback(fn, *args) schedules a function call at block end. enter_context(cm) adds a context manager to the ExitStack:

with ExitStack() as stack:
    stack.callback(print, "temizlik")
    f = stack.enter_context(open("dosya.txt"))

Cleanup happens in reverse order of addition — last added is closed first. This ensures safe management of multiple resources.

This is standard for dynamic resource management.

Exercise Schedule a callback with ExitStack

Write from contextlib import ExitStack. Inside a with ExitStack() as stack: block write stack.callback(print, "bitti") and print("içeride").

Show example solution

from contextlib import ExitStack

with ExitStack() as stack:
    stack.callback(print, "bitti")
    print("içeride")

Test yourself

Complete the ExitStack import

from contextlib import ____

with ExitStack() as stack:
    stack.callback(print, "bitti")

Show answer

from contextlib import ExitStack

with ExitStack() as stack:
    stack.callback(print, "bitti")

In which order does ExitStack run callbacks?
- Randomly
- In addition order
- In reverse order
- Only the first
Show answer

In reverse order — ExitStack runs callbacks in reverse order (LIFO).
Match ExitStack concepts

ExitStack

Dynamic manager
callback

Schedules cleanup
enter_context

Adds a cm
reverse order

Closing order

Next lesson: Summary - Context managers

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