Python in a Nutshell

Name

__getattr__

Synopsis

__getattr__(self,name)

When attribute x.y is accessed but not found by the usual procedure (i.e., where AttributeError would normally be raised), Python calls x .__getattr__('y') instead. Python does not call __getattr__ for attributes found by normal means (i.e., as keys in x .__dict__ or via x .__class__). If you want Python to call __getattr__ on every attribute reference, keep the attributes elsewhere (e.g., in another dictionary referenced by an attribute with a private name, as shown earlier in this chapter), or else write a new-style class and override __getattribute__ instead. __getattr__ should raise AttributeError if it cannot find y.