How does Python find a variable after you define it? A namespace tracks names and their corresponding objects. Think of it as a dictionary: an identifier is a key, and the object it refers to is the value. The global namespace belongs to a module and tracks its variables, functions, and classes. section 10.2.2 section 10.4.1
Check a module-level name
After defining a class and creating an instance with `task = Task("Laundry")`, you can check their entries: `assert Task is globals()["Task"]` and `assert task is globals()["task"]`. Both assertions pass. `globals()` lets you inspect the module’s global namespace. section 10.2.2
A namespace is not the same as a scope. A scope sets the boundary; its namespace holds the names available there. When Python encounters a name, it searches local, enclosing, global, then built-in scopes—the LEGB order. If no lookup succeeds, it raises `NameError`. section 10.4.1
Listing 10.7 Attempting to change a global variable
db_filename = "N/A"
def set_database(db_name):
db_filename = db_name
set_database("tasks.sqlite")
print(db_filename)
# output: "N/A"
Watch the output: assigning `db_filename` inside `set_database` does not change the module-level value. When an assignment appears ineffective, check which scope contains the name being assigned. section 10.4 section 10.4.1
Namespaces change as execution creates variables. While debugging a function, call `locals()` in the debugger to see its current local namespace and inspect the values available at that point. section 13.2.6 section 13.2.4
