pylint #6954 false "Using variable before assignment" on one-liner with-statements [resolved]

Mads Kiilerich

from __future__ import with_statement
with file('f') as f: print f.read()

gives

E:  2: Using variable 'f' before assignment

When the print statement is moved to its own line pylint correctly doesn't see an error

prioritynormal
typebug
done in0.16.0
load0.500
load left0.000
closed by<not specified>

Workflow history

from state (2)to statecommentdateUser
validation pendingresolved2009/03/23 09:53 UTCsthenault
openvalidation pending

patch applied

2009/01/26 08:59 UTCsthenault

Comments

  • 2009/01/15 00:48, written by mkiilerich

    The error message is E0601.

    In variables.VariablesChecker.visit_name a criteria for getting the error is if a variable is used on the line it is defined. That is not right in cases like this. But it seems to be what prevents the error message if it isn't used on the same line.

    But another criteria is utils.is_defined_before,  and that seems to be where the real problem is; the check  doesn't consider "with" statements. The following seems to fix the simple test case:

    --- a/checkers/utils.py
    +++ b/checkers/utils.py
    @@ -108,6 +108,9 @@
                 if getattr(_node, 'name', None) == varname:
                     return True
                 break
    +        elif isinstance(_node, astng.With):
    +            if _node.vars.name == varname:
    +                return True
             _node = _node.parent
         # possibly multiple statements on the same line using semi colon separator
         stmt = var_node.statement()
     

    I haven't been able to run the test suite yet. It is not obvious to me how to add such a 2.5-specific test. It seems like test/input/func_e0601.py could be the right place...

    • 2009/01/15 07:54, written by sthenault

      great, thanks for the patch!

      I've checked-it in the repository.

      FYI, I've added a test by adding your sample code in a file pylint/test/input/func_noerror_defined_and_used_on_same_line_py25.py :

      • the _py25 suffix makes it executed only with python 2.5
      • the _noerror_ prefix tells that no message should be issued when this file is analysed (else a file containing messages is expected to be found in pylint/test/messages/<test file name>.txt)
      • 2009/01/15 07:55, written by sthenault

        one more thing: to run the functionnal test suite, type "python test_func.py" in pylint test directory.

  • 2009/01/25 01:56, written by mkiilerich

    Please change the state from "open" to "validation pending" or something like that

add comment