之前在 PyCharm 中定义的 Python 重新声明变量 [英] Python redeclared variable defined before in PyCharm

问题描述

在编写了这段单独执行数据库查询的代码后，PyCharm 用给定的注释突出显示了第二个 i.

for i in range(records):fill.apply_proc('AddCompany', gen_add_company())对于 i 在范围内(记录):fill.apply_proc('AddConference', gen_add_conference())

<块引用>

重新声明上面定义的i"，但不使用.

它会不会有任何错误?我应该以其他方式实现它吗?

解决方案

发生的情况是与您在 C++/Java 中遇到的范围不同.在那里，您希望 i 不存在于 for 之间.事实并非如此.

你可以在工作中看到，假设记录 == 10:

for i in range(records):fill.apply_proc('AddCompany', gen_add_company())打印(我:%d"%我)对于 i 在范围内(记录):fill.apply_proc('AddConference', gen_add_conference())

你会得到你的输出 - 假设 for 没有输出:

i: 9

您收到警告的原因可能是这种事情可能会导致大脑崩溃的错误.间接解决方案包含在链接页面中；您可以考虑将您的 for 封装在一个函数中，如果这种情况发生两次以上，这可能特别有助于提高可读性.

在 列表推导式，但不是在您要问的 Python 3 中.

After having written this piece of code to execute queries on database separately, PyCharm highlighted the second i with the given comment.

for i in range(records):
    filler.apply_proc('AddCompany', gen_add_company())

for i in range(records):
    filler.apply_proc('AddConference', gen_add_conference())

Redeclared 'i' defined above without usage.

Could it be subject of any error? Should I achieve it in other way?

解决方案

What happens is the different scoping than you would get in, say, C++/Java. There you'd expect i not to exist between fors. It's not the case.

You could see that in work, assuming records == 10:

for i in range(records):
    filler.apply_proc('AddCompany', gen_add_company())

print("i: %d" % i)

for i in range(records):
    filler.apply_proc('AddConference', gen_add_conference())

You'd get in your output - assuming no output from for:

i: 9

The reason why you're getting the warning is probably that this kind of thing could lead to brain-cracking bugs. Indirect solutions are included in the linked page; one you could consider is to encase your for in a function, which might be especially good for readability if this happens more than twice.

There's also a similar case of scoping surprise in list comprehensions, but not in Python 3 you're asking about.

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