Don't use shutil backport on py3

 






 

 


  Review Request #10047
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  Created June 29, 2018 and submitted 

 


















 

  

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  sgallagh
 









 
 

  RBTools
 









 
 

  release-1.0.x
 









 
 

  
 









 
 

  
 









 
 

  4ebd931...
 






 




 

  

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  rbtools
 









 
 

  
 






 








 





  


 
 

  
On many distributions (including Fedora and RHEL 7), the backports.shutil package doesn't exist for python 3.x because it's meaningless. Instead of unconditionally including it, use the appropriate import for the python version in use.

 








  


 
 

  
Submitted this very review using rbt post on python3 with this patch applied.

 







 









 





  








 






 
 
 

  

   

    

     
    

    
    
     
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E126 continuation line over-indented for hanging indent

      		
      
       reviewbotreviewbot
      
      
       
      
     




     

      
       
       
Instead of checking the version, how about just a try/except? try: from shutil import get_terminal_size except ImportError: from backports.shutil_get_terminal_size import …

      		
      
       daviddavid
      
      
       
      
     




     

      
       
       
Can we call this install_requires instead of runtime_reqs? The "runtime" makes me think that this will actually be computed at …

      		
      
       daviddavid
      
      
       
      
     


    
   

  

 







 






  

 



















 




 

  


   

   

    
 
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       setup.py
       


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    E126 continuation line over-indented for hanging indent
    
  
    
 
    

 
    
  


    
 
    
 
      

  

 
    


    

 
    

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       rbtools/commands/status.py
       


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    Instead of checking the version, how about just a try/except?
    

    

    try:
    from shutil import get_terminal_size
except ImportError:
    from backports.shutil_get_terminal_size import get_terminal_size

    
  
    
 
    

 
    
  


    
 
    
 
      

  


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      I wanted to keep the implementation in the code and the implementation in setup.py in sync. Just in case (for example) shutil.get_terminal_size() started showing up on python2, but with different semantics. I can do the try/except if you prefer, though.
      
 
      

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      The try/except is our usual method for this case. It avoids having to make assumptions about when things show up (even if they're pretty well-understood). Plus it's about to differ anyway -- see below.
      
 
      

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    Can we call this install_requires instead of runtime_reqs? The "runtime" makes me think that this will actually be computed at runtime, whereas the list will get evaluated at the time that the package is being built.
    
  
    
 
    

 
    
  


    
 
    
 
      

  


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      Well, it was the list of things that have to be available on the system at runtime to operate. Calling them install_requires suggests to me that they are needed for performing the installation itself, which they are not.
      
 
      

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      In the modern Python world, we don't want to build a list of requirements based on the version anyway. It will break now, as we ship a single Wheel that works on Python 2 and 3 (built using 3, meaning this dependency won't end up in the package).
      

      Instead, we'll need to use the new Python version specifiers to specify when a particular version applies. This looks like:
      

      

      install_requires=[
    'colorama',
    'six>=1.8.0',
    'backports.shutil_get_terminal_size; python_version<"3.0"',
]

      

      

      Modern versions of pip and easy_install will respect this. The packages (both eggs and wheels) will be built with metadata tagging that dependency along with a Python version, and the installer will only install it on the appropriate version.
      

      (I just tested this on RBTools with both eggs and wheels and verified shutil only installed on 2.7.)
      
 
      

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      How modern are we talking about? I'm trying to make sure that RBTools keeps working on RHEL/CentOS too, which are stuck on older versions. I suppose if I have to, I'll just carry specialized patches for those releases.
      
 
      

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      setuptools 8.0 and pip 6.0 both should have this support. That puts it at December 2014. We're using these version specifiers going forward in our setup scripts, though of course distro packages can always do something a bit more custom.
      
 
      

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    Going to make relevant changes and land this. Thanks.
    
  
    
 
    

 
    
  


    
 
    
 
      

  

 
    


    

 
    

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sgallagh




   

   

  

 



 

  


   

   

    
 Review request changed

    
   


  

  

  







  

   

    Status:
   

   


    Completed

   

  




  

   

    Change Summary:
   

   

    
Pushed to release-1.0.x (c008624)