When to Use getattr vs. __getattribute__ in Python?

Understanding the Difference Between getattr and getattribute

When working with Python classes, developers often encounter the need to define custom attributes or handle missing attributes. The two methods available for this purpose are getattr and __getattribute__.

getattr vs. getattribute

The main distinction between getattr and getattribute lies in their execution order and purpose.

• __getattr__:

  • Invoked only when the attribute has not been found through the usual lookup mechanisms.
  • Useful for implementing fallbacks or dynamic access to attributes.

• __getattribute__:

  • Invoked before accessing existing attributes.
  • Requires careful implementation to avoid infinite recursions.

New-Style Classes

The documentation mentions new-style classes in the context of getattribute__. New-style classes are classes that derive from the base class object. However, this distinction is not crucial when choosing between __getattr and __getattribute__.

When to Use Which Method

In most cases, getattr is the preferred option. It allows for straightforward fallback mechanisms without the complexity of __getattribute__.

By contrast, getattribute is used in advanced scenarios where you need to manipulate or override attribute access altogether. However, it should be approached with caution due to its potential for recursive traps.

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