OLife'S
data =; iterator = iter(data) while True: try: val = next(iterator) except StopIteration: break if val % 2: continue print(val) else: print('Iterator exhausted')
Iteration Patterns

Meaning

This chunk manually iterates over an iterable using a while‑True loop with explicit calls to next() and StopIteration handling. It is useful when you need fine‑grained control over the iteration process or want to illustrate the iterator protocol for teaching purposes. You reach for it when demonstrating how a Python for‑loop works under the hood or when a for‑loop cannot be used directly.

Primary Function

Iteration control

Communicative Purpose

Enables explicit handling of iterator exhaustion while allowing custom actions for each element.

Pattern

while True: try: item = next(iterator) except StopIteration: break if condition: continue action else: else_action

Core Structure

while True: try: ... = next(...) except StopIteration: break if ...: continue ... else: ...

Função primária

Iteration control

Propósito comunicativo

Enables explicit handling of iterator exhaustion while allowing custom actions for each element.

Situações de gatilho

Data processing: iterating over a list while needing to skip certain items and perform cleanup after exhaustion Teaching: demonstrating the underlying mechanics of a for‑loop for students

Contextos

Educational tutorials, low‑level data pipelines, custom iterator implementations

Padrão

while True: try: item = next(iterator) except StopIteration: break if condition: continue action else: else_action

Estrutura central

while True: try: ... = next(...) except StopIteration: break if ...: continue ... else: ...

Slots de substituição

item_var: variable receiving each element; iterator_var: the iterator object; condition: boolean expression to skip items; action: code to run for items that pass condition; else_action: code to run after loop finishes without break

Colocados típicos

  • for loop
  • list comprehension
  • itertools
  • generator functions

Substituições comuns

  • for val in data: if val % 2: continue
  • print(val)
  • else: print('Iterator exhausted')

Erros comuns

Assuming else runs after break: leads to unexpected else execution; forgetting StopIteration handling leads to infinite loop; missing else block when needed leads to missing cleanup logic

Similar / contraste

for-else loop: else runs when loop not broken by break, unlike while-else which runs when condition becomes false

Interferências

Coming from C-style while loops: may forget to catch StopIteration, causing unhandled exception

Família do chunk

  • manual iteration
  • iterator protocol
  • for-else pattern
  • while loop with break

Nuance

Else block never executes because loop exits only via break; pattern is verbose and less readable than a for loop

Efeito pragmático

Makes iteration mechanics explicit for teaching; obscures intent and is error-prone in production code

Dica de memória

Manual iteration with try/except StopIteration mimics a for loop's internals

Nota

This pattern manually implements the iterator protocol with try/except StopIteration and an else clause that only runs when the loop exits via the condition becoming false – which never happens here because the loop only exits via break, making the else block effectively dead code. It is more verbose and error‑prone than a simple for-else loop.

Upgrade path

for val in data: if val % 2: continue print(val) else: print('Iterator exhausted')

Frequência: LowFormulaicidade: Semi-fixedTipo de construção: while-true try-except StopIteration loop with continue and else clause (manual iterator loop mimicking a for-else)Prioridade de aquisição: Recognition firstPrioridade de output: InputTag de espaçamento: Medium-term

Log in to save chunks.