blocks|key|563566|text|data+=+[4,+5,+6]+#+Your+global+variable

def+print_data(data):+#+<--+Pass+in+a+parameter+called+"data"
++++print+data++#+<--+Note:+You+can+access+global+variable+inside+your+function,+BUT+for+now,+which+is+which?+the+parameter+or+the+global+variable?+Confused,+huh?

print_data(data)|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|563567|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>data = [4, 5, 6] # Your global variable

def print_data(data): # &lt;-- Pass in a parameter called &quot;data&quot;
 print data # &lt;-- Note: You can access global variable inside your function, BUT for now, which is which? the parameter or the global variable? Confused, huh?

print_data(data)
</code></pre>

blocks|key|563591|text|这取决于函数的长度。函数越长，将来修改它的人就越有可能编写data，认为它意味着全局。实际上，它的意思是本地，但是因为函数太长，所以对他们来说并不明显，存在一个具有该名称的本地。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|563592|对于您的示例函数，我认为隐藏全局一点也不坏。|563593|entityMap^0|T|4|0|0^^$0|@$1|2|3|4|5|6|7|J|8|@$9|K|A|L|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|M|8|@]|D|@]|E|$]]|$1|H|3|-4|5|6|7|N|8|@]|D|@]|E|$]]]|I|$]]

It depends how long the function is. The longer the function, the greater the chance that someone modifying it in future will write <code>data</code> thinking that it means the global. In fact, it means the local, but because the function is so long, it's not obvious to them that there exists a local with that name.
For your example function, I think that shadowing the global is not bad at all.

blocks|key|563614|text|上面的代码片段没有什么大不了的，但是想象一个函数有更多的参数和更多的代码行。然后，您决定将data参数重命名为yadda，但忽略了它在函数体中使用的一个位置.现在data指的是全局，而你开始有奇怪的行为--如果你没有全局名称data，你会有一个更明显的NameError。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|563615|还请记住，在Python中，所有东西都是一个对象(包括模块、类和函数)，因此函数、模块或类没有不同的名称空间。另一个场景是在模块顶部导入函数foo，并在函数体的某个位置使用它。然后向函数中添加一个新参数，并将其命名为“厄运-+foo”。|563616|最后，内置函数和类型也存在于相同的命名空间中，并且可以以相同的方式隐藏。|563617|如果功能短、命名良好和单元测试复盖范围良好，那么这都不是什么大问题，但是，有时候您必须维护不太完美的代码，并且警告您这些可能的问题可能会有帮助。|563618|entityMap^0|19|4|1J|5|29|4|34|4|3I|9|0|1Y|3|35|3|0|0|0^^$0|@$1|2|3|4|5|6|7|N|8|@$9|O|A|P|B|C]|$9|Q|A|R|B|C]|$9|S|A|T|B|C]|$9|U|A|V|B|C]|$9|W|A|X|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Y|8|@$9|Z|A|10|B|C]|$9|11|A|12|B|C]]|D|@]|E|$]]|$1|H|3|I|5|6|7|13|8|@]|D|@]|E|$]]|$1|J|3|K|5|6|7|14|8|@]|D|@]|E|$]]|$1|L|3|-4|5|6|7|15|8|@]|D|@]|E|$]]]|M|$]]

There isn't any big deal in your above snippet, but imagine a function with a few more arguments and quite a few more lines of code. Then you decide to rename your <code>data</code> argument as <code>yadda</code>, but miss one of the places it is used in the function's body... Now <code>data</code> refers to the global, and you start having weird behaviour - where you would have a much more obvious <code>NameError</code> if you didn't have a global name <code>data</code>.
Also remember that in Python everything is an object (including modules, classes and functions), so there's no distinct namespaces for functions, modules or classes. Another scenario is that you import function <code>foo</code> at the top of your module, and use it somewhere in your function body. Then you add a new argument to your function and named it - bad luck - <code>foo</code>.
Finally, built-in functions and types also live in the same namespace and can be shadowed the same way.
None of this is much of a problem if you have short functions, good naming and a decent unit test coverage, but well, sometimes you have to maintain less than perfect code and being warned about such possible issues might help.

blocks|key|565317|text|在某些情况下，一个很好的解决方法可能是将变量和代码移动到另一个函数中：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|565318|def+print_data(data):
++++print+data

def+main():
++++data+=+[4,+5,+6]
++++print_data(data)

main()|code-block|syntax|javascript|565319|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

A good workaround in some cases may be to move the variables and code to another function:
<pre><code>def print_data(data):
 print data

def main():
 data = [4, 5, 6]
 print_data(data)

main()
</code></pre>

blocks|key|3052657|text|目前投票最多并被接受的答案和这里的大多数答案都忽略了重点。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3052658|不管您的函数是多长时间，或者您如何将变量命名为描述符(希望最大限度地减少潜在名称冲突的可能性)。|3052659|函数的局部变量或其参数碰巧在全局范围内共享名称这一事实是完全不相关的。事实上，无论您多么谨慎地选择局部变量名称，您的函数都无法预见“我的酷名yadda将来是否也会被用作全局变量？”解决方案是什么？不要担心这一点！正确的思维方式是设计您的函数来使用输入，并且只使用它在签名中的参数。这样，您就不需要关心(或将要)在全局范围内是什么，然后隐藏就完全不是问题了。|style|CODE|BOLD|3052660|换句话说，只有当函数需要使用同名局部变量和全局变量时，隐藏问题才重要。但首先你应该避免这样的设计。OP的代码实际上没有这样的设计问题。只是PyCharm不够聪明，它会发出警告以防万一。因此，为了使PyCharm高兴，同时也使我们的代码整洁，可以看到这个解决方案引用了西莱夫斯克的回答来完全删除全局变量。|3052661|def+print_data(data):
++++print+data

def+main():
++++data+=+[4,+5,+6]
++++print_data(data)

main()|code-block|syntax|javascript|3052662|这是“解决”这个问题的正确方法，方法是修复/删除全局事物，而不是调整当前的本地函数。|3052663|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/20125739/728675|1|https://stackoverflow.com/a/39201621/728675^0|0|D|0|0|0|1Y|5|2Y|T|0|3P|8|1|0|0|0^^$0|@$1|2|3|4|5|6|7|13|8|@]|9|@$A|14|B|15|1|16]]|C|$]]|$1|D|3|E|5|6|7|17|8|@]|9|@]|C|$]]|$1|F|3|G|5|6|7|18|8|@$A|19|B|1A|H|I]|$A|1B|B|1C|H|J]]|9|@]|C|$]]|$1|K|3|L|5|6|7|1D|8|@]|9|@$A|1E|B|1F|1|1G]]|C|$]]|$1|M|3|N|5|O|7|1H|8|@]|9|@]|C|$P|Q]]|$1|R|3|S|5|6|7|1I|8|@]|9|@]|C|$]]|$1|T|3|-4|5|6|7|1J|8|@]|9|@]|C|$]]]|U|$V|$5|W|X|Y|C|$Z|10]]|11|$5|W|X|Y|C|$Z|12]]]]

<a href="https://stackoverflow.com/a/20125739/728675">The currently most up-voted and accepted answer</a> and most answers here miss the point.
It doesn't matter how long your function is, or how you name your variable descriptively (to hopefully minimize the chance of potential name collision).
The fact that your function's local variable or its parameter happens to share a name in the global scope is completely irrelevant. And in fact, no matter how carefully you choose you local variable name, your function can never foresee &quot;whether my cool name <code>yadda</code> will also be used as a global variable in future?&quot;. The solution? Simply don't worry about that! The correct mindset is to design your function to consume input from and only from its parameters in signature. That way you don't need to care what is (or will be) in global scope, and then shadowing becomes not an issue at all.
In other words, the shadowing problem only matters when your function need to use the same name local variable and the global variable. But you should avoid such design in the first place. The OP's code does not really have such design problem. It is just that PyCharm is not smart enough and it gives out a warning just in case. So, just to make PyCharm happy, and also make our code clean, see this solution quoting from <a href="https://stackoverflow.com/a/39201621/728675">silyevsk's answer</a> to remove the global variable completely.
<pre><code>def print_data(data):
 print data

def main():
 data = [4, 5, 6]
 print_data(data)

main()
</code></pre>
This is the proper way to &quot;solve&quot; this problem, by fixing/removing your global thing, not adjusting your current local function.

blocks|key|3052687|text|这样做：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3052688|data+=+[4,+5,+6]

def+print_data():
++++global+data
++++print(data)

print_data()|code-block|syntax|javascript|3052689|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Do this:

<pre><code>data = [4, 5, 6]

def print_data():
 global data
 print(data)

print_data()
</code></pre>

blocks|key|563680|text|它看起来像是100%25的吡喃代码模式。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|563681|请参见：|563682|https://docs.pytest.org/en/latest/fixture.html#conftest-py-sharing-fixture-functions|563683|我也有同样的问题，这就是我找到这篇文章的原因;)|563684|#+./tests/test_twitter1.py
import+os
import+pytest

from+mylib+import+db
#+...

@pytest.fixture
def+twitter():
++++twitter_+=+db.Twitter()
++++twitter_._debug+=+True
++++return+twitter_

@pytest.mark.parametrize("query,expected",+[
++++("BANCO+PROVINCIAL",+8),
++++("name",+6),
++++("castlabs",+42),
])
def+test_search(twitter:+db.Twitter,+query:+str,+expected:+int):

++++for+query+in+queries:
++++++++res+=+twitter.search(query)
++++++++print(res)
++++++++assert+res|code-block|syntax|javascript|563685|它将使用This+inspection+detects+shadowing+names+defined+in+outer+scopes.发出警告|style|CODE|563686|要解决这个问题，只需将twitter夹具移动到./tests/conftest.py中即可。|563687|#+./tests/conftest.py
import+pytest

from+syntropy+import+db


@pytest.fixture
def+twitter():
++++twitter_+=+db.Twitter()
++++twitter_._debug+=+True
++++return+twitter_|563688|并移除twitter夹具，如./tests/test_twitter2.py中的|563689|#+./tests/test_twitter2.py
import+os
import+pytest

from+mylib+import+db
#+...

@pytest.mark.parametrize("query,expected",+[
++++("BANCO+PROVINCIAL",+8),
++++("name",+6),
++++("castlabs",+42),
])
def+test_search(twitter:+db.Twitter,+query:+str,+expected:+int):

++++for+query+in+queries:
++++++++res+=+twitter.search(query)
++++++++print(res)
++++++++assert+res|563690|这将使QA、PyCharm和每个人都感到高兴。|563691|entityMap|0|LINK|mutability|MUTABLE|url|https://docs.pytest.org/en/stable/|1^0|B|2|0|0|0|0|2C|1|0|0|0|4|1S|0|B|7|N|J|0|0|3|7|E|O|0|0|0^^$0|@$1|2|3|4|5|6|7|1B|8|@]|9|@$A|1C|B|1D|1|1E]]|C|$]]|$1|D|3|E|5|6|7|1F|8|@]|9|@]|C|$]]|$1|F|3|G|5|6|7|1G|8|@]|9|@$A|1H|B|1I|1|1J]]|C|$]]|$1|H|3|I|5|6|7|1K|8|@]|9|@]|C|$]]|$1|J|3|K|5|L|7|1L|8|@]|9|@]|C|$M|N]]|$1|O|3|P|5|6|7|1M|8|@$A|1N|B|1O|Q|R]]|9|@]|C|$]]|$1|S|3|T|5|6|7|1P|8|@$A|1Q|B|1R|Q|R]|$A|1S|B|1T|Q|R]]|9|@]|C|$]]|$1|U|3|V|5|L|7|1U|8|@]|9|@]|C|$M|N]]|$1|W|3|X|5|6|7|1V|8|@$A|1W|B|1X|Q|R]|$A|1Y|B|1Z|Q|R]]|9|@]|C|$]]|$1|Y|3|Z|5|L|7|20|8|@]|9|@]|C|$M|N]]|$1|10|3|11|5|6|7|21|8|@]|9|@]|C|$]]|$1|12|3|-4|5|6|7|22|8|@]|9|@]|C|$]]]|13|$14|$5|15|16|17|C|$18|19]]|1A|$5|15|16|17|C|$18|G]]]]

It looks like it is 100% a <a href="https://docs.pytest.org/en/stable/" rel="nofollow noreferrer">pytest</a> code pattern.
See:
<a href="https://docs.pytest.org/en/latest/fixture.html#conftest-py-sharing-fixture-functions" rel="nofollow noreferrer">pytest fixtures: explicit, modular, scalable</a>
I had the same problem with it, and this is why I found this post ;)
<pre><code># ./tests/test_twitter1.py
import os
import pytest

from mylib import db
# ...

@pytest.fixture
def twitter():
 twitter_ = db.Twitter()
 twitter_._debug = True
 return twitter_

@pytest.mark.parametrize(&quot;query,expected&quot;, [
 (&quot;BANCO PROVINCIAL&quot;, 8),
 (&quot;name&quot;, 6),
 (&quot;castlabs&quot;, 42),
])
def test_search(twitter: db.Twitter, query: str, expected: int):

 for query in queries:
 res = twitter.search(query)
 print(res)
 assert res
</code></pre>
And it will warn with <code>This inspection detects shadowing names defined in outer scopes.</code>
To fix that, just move your <code>twitter</code> fixture into <code>./tests/conftest.py</code>
<pre><code># ./tests/conftest.py
import pytest

from syntropy import db


@pytest.fixture
def twitter():
 twitter_ = db.Twitter()
 twitter_._debug = True
 return twitter_
</code></pre>
And remove the <code>twitter</code> fixture, like in <code>./tests/test_twitter2.py</code>:
<pre><code># ./tests/test_twitter2.py
import os
import pytest

from mylib import db
# ...

@pytest.mark.parametrize(&quot;query,expected&quot;, [
 (&quot;BANCO PROVINCIAL&quot;, 8),
 (&quot;name&quot;, 6),
 (&quot;castlabs&quot;, 42),
])
def test_search(twitter: db.Twitter, query: str, expected: int):

 for query in queries:
 res = twitter.search(query)
 print(res)
 assert res
</code></pre>
This will be make happy for QA, PyCharm and everyone.

blocks|key|3052735|text|我喜欢在PyCharm的右上角看到绿色的滴答声。我在变量名后面加上下划线，以清除此警告，以便重点关注重要的警告。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3052736|data+=+[4,+5,+6]

def+print_data(data_):
++++print(data_)

print_data(data)|code-block|syntax|javascript|3052737|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I like to see a green tick in the top right corner in PyCharm. I append the variable names with an underscore just to clear this warning so I can focus on the important warnings.
<pre><code>data = [4, 5, 6]

def print_data(data_):
 print(data_)

print_data(data)
</code></pre>

blocks|key|1972629|text|若要忽略警告，正如Chistopher在评论中所说的，您可以在上面进行评论。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1972630|#+noinspection+PyShadowingNames|code-block|syntax|javascript|1972631|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

To ignore the warning, as Chistopher said in a comment, you can comment above it
<pre><code># noinspection PyShadowingNames
</code></pre>

blocks|key|3052763|text|我认为这条规则没有多大帮助。我只是通过访问Settings+->+Editor+->+Inspections，然后检查这个规则来禁用它：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3052764|Shadowing+names+from+outer+scope|code-block|syntax|javascript|3052765|entityMap^0|L|8|X|6|17|B|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]|$9|P|A|Q|B|C]|$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|U|8|@]|D|@]|E|$]]]|L|$]]

I think this rule doesn't help much. I simply disabled it by going to <code>Settings</code> -&gt; <code>Editor</code> -&gt; <code>Inspections</code> and then checking off this rule:
<pre><code>Shadowing names from outer scope
</code></pre>

I just switched to PyCharm and I am very happy about all the warnings and hints it provides me to improve my code. Except for this one which I don't understand:
<blockquote>
This inspection detects shadowing names defined in outer scopes.
</blockquote>
I know it is bad practice to access variable from the outer scope, but what is the problem with shadowing the outer scope?
Here is one example, where PyCharm gives me the warning message:
<pre><code>data = [4, 5, 6]

def print_data(data): # &lt;-- Warning: &quot;Shadows 'data' from outer scope
 print data

print_data(data)
</code></pre>

What is the problem with shadowing names defined in outer scopes?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我刚转到PyCharm，我很高兴看到它为我提供了改进代码的所有警告和提示。除了这个我不明白的：此检查检测外部作用域中定义的隐藏名称。我知道从外部范围访问变量是不好的做法，但是隐藏外部范围有什么问题呢？下面是一个例子，其中PyCharm给出了警告消息：data = [4, 5, 6]def print_data(data...

问在外部范围中定义的名称隐藏有什么问题？
EN

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问在外部范围中定义的名称隐藏有什么问题？
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