Namespace Rules: The Whole Story
Now that we’ve seen class and instance objects, the Python namespace story is complete; for reference, let’s quickly summarize all the rules used to resolve names. The first things you need to remember are that qualified and unqualified names are treated differently, and that some scopes serve to initialize object namespaces:
Unqualified names (
X) deal with scopes.Qualified names (
object.X) use object namespaces.Scopes initialize object namespaces (in modules and classes).
Unqualified Names: Global Unless Assigned
Unqualified names follow the LGB rules we outlined for functions in Chapter 4.
- Assignment:
X = value Makes names local: creates or changes name
Xin the current local scope, unless declaredglobal- Reference:
X Looks for name
Xin the current local scope, then the current global scope, then the built-in scope
Qualified Names: Object Namespaces
Q ualified names refer to attributes of specific objects and obey the rules we met when discussing modules. For instance and class objects, the reference rules are augmented to include the inheritance search procedure:
- Assignment:
object.X=value Creates or alters the attribute name
Xin the namespace of the object being qualified- Reference:
object.X Searches for the attribute name
Xin the object, then in all accessible classes above it (but not for modules)
N amespace Dictionaries
Finally, in Chapter 5, we saw that module namespaces were actually implemented as dictionaries and exposed with the built-in ...