---
title: ensure that both __exit__ and __enter__ are defined
description: Datadog, the leading service for cloud-scale monitoring.
breadcrumbs: >-
  Docs > Datadog Security > Code Security > Static Code Analysis (SAST) > SAST
  Rules > ensure that both __exit__ and __enter__ are defined
---

# ensure that both __exit__ and __enter__ are defined

{% callout %}
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{% alert level="danger" %}
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{% /callout %}

## Metadata{% #metadata %}

**ID:** `python-best-practices/ctx-manager-enter-exit-defined`

**Language:** Python

**Severity:** Error

**Category:** Best Practices

## Description{% #description %}

Methods `__enter__` and `__exit__` must be declared together. If one method is missing, we should make sure both are defined.

#### Learn More{% #learn-more %}

- [contextlib documentation](https://docs.python.org/3/library/contextlib.html)

## Non-Compliant Code Examples{% #non-compliant-code-examples %}

```python
class Ctx:
    def __exit__(self, *exc):  # the method __enter__ should be defined.
        pass
```

```python
class Ctx:
    def __enter__(self):  # the method __exit__ should also be defined.
        pass
```

## Compliant Code Examples{% #compliant-code-examples %}

```python
class Ctx:
    def __enter__(self):
        pass
    def __exit__(self, *exc):
        pass
```
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