未验证 提交 33bcfa74 编写于 作者: S Satwik Kansal 提交者: GitHub

Minor changes to nonlocal explanation

Closes https://github.com/satwikkansal/wtfpython/issues/193
上级 7525e800
......@@ -1987,6 +1987,8 @@ Okay, now it's deleted :confused:
### ▶ The out of scope variable
<!-- Example ID: 75c03015-7be9-4289-9e22-4f5fdda056f7 --->
1\.
```py
a = 1
def some_func():
......@@ -1995,8 +1997,10 @@ def some_func():
def another_func():
a += 1
return a
```
2\.
```py
def some_closure_func():
a = 1
def some_inner_func():
......@@ -2026,7 +2030,7 @@ UnboundLocalError: local variable 'a' referenced before assignment
#### 💡 Explanation:
* When you make an assignment to a variable in scope, it becomes local to that scope. So `a` becomes local to the scope of `another_func`, but it has not been initialized previously in the same scope, which throws an error.
* To modify the outer scope variable `a` in `another_func`, use `global` keyword.
* To modify the outer scope variable `a` in `another_func`, we have to use the `global` keyword.
```py
def another_func()
global a
......@@ -2039,8 +2043,8 @@ UnboundLocalError: local variable 'a' referenced before assignment
>>> another_func()
2
```
* In `another_closure_func`, `a` becomes local to the scope of `another_inner_func`, but it has not been initialized previously in the same scope, which is why it throws an error.
* To modify the outer scope variable `a` in `another_inner_func`, use the `nonlocal` keyword.
* In `another_closure_func`, `a` becomes local to the scope of `another_inner_func`, but it has not been initialized previously in the same scope, which is why it throws an error.
* To modify the outer scope variable `a` in `another_inner_func`, use the `nonlocal` keyword. The nonlocal statement is used to refer to variables defined in the nearest outer (excluding the global) scope.
```py
def another_func():
a = 1
......@@ -2056,7 +2060,7 @@ UnboundLocalError: local variable 'a' referenced before assignment
>>> another_func()
2
```
* The keywords `global` and `nonlocal` are ways to simply tell the python interpreter to not delcare new variables, but to just look them up from the corresponding scope.
* The keywords `global` and `nonlocal` tell the python interpreter to not delcare new variables and look them up in the corresponding outer scopes.
* Read [this](http://sebastianraschka.com/Articles/2014_python_scope_and_namespaces.html) short but an awesome guide to learn more about how namespaces and scope resolution works in Python.
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