[Python-ideas] SyntaxWarning for for/while/else without break or return?
steve at pearwood.info
Sat Oct 10 14:15:07 CEST 2009
On Sat, 10 Oct 2009 10:22:11 pm Nick Coghlan wrote:
> For the record, there are three cases (not counting Py3k warnings)
> where we currently issue syntax warnings (but generate valid code
> 1. Using "import *" at function level (as it disables local variable
`import *` inside a function is illegal in Python3. It's a warning in
Python2.x only because of backwards compatibility. This was the primary
use-case for the warning module in the first place: to warn when
functionality is being deprecated and will be removed in the future.
Even though `import *` at the module level is a frequent source of bugs
and confusion even for experienced coders, and the usual advice is Just
Don't Do It, Python does not generate a warning for that case.
> 2. Referencing a global variable before declaring it as such:
> 3. Assigning to a global variable before declaring it as such:
These are insignificant variations of the same act: using a global
before declaring it. They may have two different error messages, but
the underlying problem is the same.
> All 3 could easily be left to pylint/pychecker style tools, but were
> deemed worthy of being warned about by the compiler itself.
The first could not, because it is functionality being removed.
The second and third are warning about the same thing, and this is a
genuine case of Python warning about a stylistic issue.
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