getAttr

getattr is a built-in function in Python that retrieves the value of an attribute from an object using the attribute's name as a string. It takes two required arguments, the object and the attribute name, and an optional third argument, default, which is returned if the attribute is not found. If the attribute exists, its value is returned; if it does not exist and a default is provided, the default value is returned; otherwise an AttributeError is raised.

Attribute lookup performed by getattr follows Python’s normal attribute access rules. This means that __getattribute__ and, if present, __getattr__ on the object are consulted, and descriptors, properties, or __get__ methods may influence the result. The default parameter only affects the case where the attribute is missing, not when an attribute access raises an exception during evaluation.

Common uses of getattr include dynamic access to attributes when the attribute name is determined at runtime, such as within loops or metaprogramming. It is often contrasted with dot notation, which requires a constant attribute name. The hasattr function can be used to test for the existence of an attribute, and it internally calls getattr and handles AttributeError.

Examples:

- getattr(obj, 'attr') returns obj.attr if it exists.

- getattr(obj, 'attr', default) returns default when obj has no attribute named 'attr'.

- getattr(module, 'name') can access module attributes programmatically, without hardcoding the name.

getattr is a fundamental tool for dynamic attribute access in Python and is widely used in libraries and frameworks that operate on user-specified or runtime-determined attributes.