# Source: https://docs.datadoghq.com/security/code_security/static_analysis/static_analysis_rules/python-best-practices/class-methods-use-self.md

---
title: Class methods should use self as first argument
description: Datadog, the leading service for cloud-scale monitoring.
breadcrumbs: >-
  Docs > Datadog Security > Code Security > Static Code Analysis (SAST) > SAST
  Rules > Class methods should use self as first argument
---

# Class methods should use self as first argument

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## Metadata{% #metadata %}

**ID:** `python-best-practices/class-methods-use-self`

**Language:** Python

**Severity:** Error

**Category:** Best Practices

## Description{% #description %}

In a class method (that is not a class method nor a static method), the first argument must be `self` by convention.

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

- [Method Objects on the Python documentation](https://docs.python.org/3.8/tutorial/classes.html#method-objects)
- [PEP8 style guide](https://peps.python.org/pep-0008/#function-and-method-arguments)

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

```python
class Foo:
	def bar(bar):  # use def bar(self) instead
		pass
```

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

```python
class Foo:
	@staticmethod
	def static_method(bar):
		pass

	@classmethod
	def class_method(bar):
		pass

	def __call__(cls, *args, **kwargs):
		pass
	
class IFoo(Interface): # zope interfaces won't get flagged
	def method(i):
		pass
```
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