Home/ Questions/Is It Okay To Fix the attributeerror: __enter__ problem?
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Alice Goncalves
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Asked: 2022-05-12T10:35:40+00:00 In:

Is It Okay To Fix the attributeerror: __enter__ problem?

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This is the program I run:

with ParamExample(URI) as pe:
  with MotionCommander(pe, default_height=0.3)as mc:

After I run, it returns an error:

Traceback (most recent call last):
 File "test44.py", line 156, in <module>
 with ParamExample(URI) as pe:
 AttributeError: __enter__

Does anyone have any suggestions for the problem below: attributeerror: __enter__ in the python- How to correct it?

python-3.x
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2 Answers

  1. Best Answer
    Expert

    The cause: This error happens because you don’t have the __enter__ method on your class.

    Solution: You can resolve this error by two ways. The first way is you need indent the second with block so that it’s actually in the first. The second way is substituting these lines with:

    with ParamExample(URI) as pe, MotionCommander(pe, default_height=0.3) as mc:

    It is similar with interlocking these two context managers (blocks need to used inthe name of the objects).

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  2. Additional code would be greatly appreciated, especially the ParamExample implementation. However, I assume you are missing __enter__ (and possibly __exit__) on this class.

    If you use the with block of python the object in with statement gets its __enter__method called. The block within the with then runs and the __exit__ is called (optionally with exception information if one was raised). This error will occur if your class doesn’t have a __enter__.

    Side note: You can either indent with block 2 so it is actually within the first or replace these two lines by 

    with ParamExample(URI) as pe, MotionCommander(pe, default_height=0.3) as mc:

    This is equivalent to nesting these context managers (the names of objects used by with blocs).

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