Re: [python-control-discuss] NoneType and circular relative imports

[Richard M. <mu...@cd...>]

Both of these issues should now be fixed in the latest version of trunk.  Let me know if you continue to have problems.

-richard

On 25 Oct 2012, at 23:58 , Dale Lukas Peterson <haz...@gm...> wrote:

> In src/lti.py, NoneType is being imported and used in the Lti class in
> two locations.  Is there a reason this can't be just None?  NoneType
> is deprecated in Python3 and this is causing issues for me.
> 
> Also, I am getting this import error when I import control:
> ---------------------------------------------------------------------------
> ImportError                               Traceback (most recent call last)
> <ipython-input-1-4964879682bf> in <module>()
> ----> 1 import control
> 
> /home/hazelnusse/usr/lib64/python3.2/site-packages/control-0.6a-py3.2.egg/control/__init__.py
> in <module>()
>     58 # Import functions from within the control system library
>     59 #! Should probably only import the exact functions we use...
> ---> 60 from .bdalg import series, parallel, negate, feedback
>     61 from .delay import pade
>     62 from .dtime import sample_system
> 
> /home/hazelnusse/usr/lib64/python3.2/site-packages/control-0.6a-py3.2.egg/control/bdalg.py
> in <module>()
>     53
>     54 import scipy as sp
> ---> 55 from . import xferfcn as tf
>     56 from . import statesp as ss
>     57
> 
> /home/hazelnusse/usr/lib64/python3.2/site-packages/control-0.6a-py3.2.egg/control/xferfcn.py
> in <module>()
>     82 from .lti import Lti, timebaseEqual, timebase, isdtime
>     83 from warnings import warn
> ---> 84 from . import statesp
>     85
>     86 class TransferFunction(Lti):
> 
> /home/hazelnusse/usr/lib64/python3.2/site-packages/control-0.6a-py3.2.egg/control/statesp.py
> in <module>()
>     83 import warnings
>     84 from .lti import Lti, timebaseEqual, isdtime
> ---> 85 from . import xferfcn
>     86
>     87 class StateSpace(Lti):
> 
> ImportError: cannot import name xferfcn
> 
> I noticed that xferfcn.py has:
> from . import statesp
> 
> and that statesp.py has:
> from . import xferfcn
> 
> I am guessing is a circular dependency issue.  From what I can tell,
> each of these modules only imports these to do some type checking of
> arguments.
> 
> Luke
> 
> 
> -- 
> “People call me a perfectionist, but I'm not. I'm a rightist. I do
> something until it's right, and then I move on to the next thing.”
> ― James Cameron
> 
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