Remove LicenseInfo.private_data and help extensibility.

 






 

 


  Review Request #14496
  —
  Created June 29, 2025 and updated 

 




















 

  

   Information

  





 
 

  chipx86
 









 
 

  Review Board
 









 
 

  release-7.1.x
 









 
 

  
 









 
 

  
 






 




 

  

   Reviewers

  





 
 

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Originally when the new licensing code was added, the intent was to back

license representations by a LicenseInfo and to allow license

providers to extend that by plugging state into a private_data member.


Since the original design, support for LicenseInfo subclasses was

added, largely removing the need for private_data. In practice,

though, the LicenseInfo dataclass could not be extended with new

required arguments due to the way that the dataclass was registered.

By default, dataclasses register fields as positional arguments instead

of keyword-only arguments, and this means that any field registered

after the last field with a default must itself have a default, even in

subclasses. This isn't ideal for this purpose.


We can't use kw_only=True, since that's only available on Python 3.10

and higher, and there's no getting around the internal logic that

impacts subclasses. Plus, dataclasses are slow and truly necessary, just

a convenience.


So to help facilitate License Provider backends with custom state, and

avoid the dataclass issues, this has been converted to a standard class.

This will also make it easier for subclasses to override it in a

consistent way without having to tie into the dataclass-specific

post-construction hooks.

 








  


 
 

  
Unit tests pass.


Successfully created and used subclasses of LicenseInfo with new

required fields.

 







 









 





  

 


 
 

  



 

  
   


    Summary
    ID

   

  
  

   


    

     

      Remove LicenseInfo.private_data and help extensibility.
      
Originally when the new licensing code was added, the intent was to back
license representations by a `LicenseInfo` and to allow license
providers to extend that by plugging state into a `private_data` member.

Since the original design, support for `LicenseInfo` subclasses was
added, largely removing the need for `private_data`. In practice,
though, the `LicenseInfo` dataclass could not be extended with new
required arguments due to the way that the dataclass was registered.
By default, dataclasses register fields as positional arguments instead
of keyword-only arguments, and this means that any field registered
after the last field with a default must itself have a default, even in
subclasses. This isn't ideal for this purpose.

We can't use `kw_only=True`, since that's only available on Python 3.10
and higher, and there's no getting around the internal logic that
impacts subclasses. Plus, dataclasses are slow and truly necessary, just
a convenience.

So to help facilitate License Provider backends with custom state, and
avoid the dataclass issues, this has been converted to a standard class.
This will also make it easier for subclasses to override it in a
consistent way without having to tie into the dataclass-specific
post-construction hooks.

     


    		
    9982f25aa7714bd7119795589848679e127073e2

   



  
 




 













 






 
 
 

  

   

    

     
    

    
    
     
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      Description
      From
      Last Updated
     

    
    



     

      
       
       
I thought we can't use this on Python 3.8 or 3.9?

      		
      
       daviddavid
      
      
       
      
     


    
   

  

 







 






  

 



















 




 




 














 





 

  

   




david




   

   







  

 



 

  


   

   

    
 
david



    
   


  

  

  



    




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       reviewboard/licensing/license.py
       


        (Diff revision 1)


       
      
     
    
        
    
     
     
    

     
     
    

        
   
    
  
    
 
    

   
    
    
    




    
 
    
  
  
  

  
  
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    I thought we can't use this on Python 3.8 or 3.9?
    
  
    
 
    

 
    
  


    
 
    
 
      

  


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      We can't. I realized this after putting it up yesterday, and went off in search of the best solution here.
      

      Tried backporting the 3.13 version of dataclasses, which has this and a bunch more features. But that uses match syntax.
      

      Tried 3.10, which is the minimum with kw_only. That had other issues that weren't worth pursuing.
      

      Ultimately I decided to just rewrite this as a normal class, but called it a night before I finished. That'll be up today.
      

      Fun fact: dataclasses turn out to be about 33x slower to define or subclass than a normal equivalent class. Not a big deal unless doing it dynamically and a lot, but I feel less good about sprinkling them everywhere. Curious how Django and Pydantic models compare.
      
 
      

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chipx86




   

   

  

 



 

  


   

   

    
 Review request changed

    
   


  

  

  









  

   

    Change Summary:
   

   

    
Changed LicenseInfo to be a standard class.

   

  








  

   

    Description:
   

   

    
     
Originally when the new licensing code was added, the intent was to back
     license representations by a LicenseInfo and to allow license
     providers to extend that by plugging state into a private_data member.
     

     
Since the original design, support for LicenseInfo subclasses was
     added, largely removing the need for private_data. In practice,
     though, the LicenseInfo dataclass could not be extended with new
     required arguments due to the way that the dataclass was registered.
     By default, dataclasses register fields as positional arguments instead
     of keyword-only arguments, and this means that any field registered
     after the last field with a default must itself have a default, even in
     subclasses. This isn't ideal for this purpose.
     

 ~   
To help facilitate License Provider backends with custom state, we now
 ~   register the dataclass with kw_only=True, and remove private_data.
   ~ 
We can't use kw_only=True, since that's only available on Python 3.10
   ~ and higher, and there's no getting around the internal logic that
   + impacts subclasses. Plus, dataclasses are slow and truly necessary, just
   + a convenience.
     

 ~   
Going forward, we should ensure that all dataclasses use kw_only=True
 ~   to help with forward-compatibility and extensibility.
   ~ 
So to help facilitate License Provider backends with custom state, and
   ~ avoid the dataclass issues, this has been converted to a standard class.
   + This will also make it easier for subclasses to override it in a
   + consistent way without having to tie into the dataclass-specific
   + post-construction hooks.

   

  





  

   

    Commits:
   

   

    





 

  
   


    

    Summary
    ID

   

  
  

   


    

    

     

      Remove LicenseInfo.private_data and help extensibility.
      
Originally when the new licensing code was added, the intent was to back
license representations by a `LicenseInfo` and to allow license
providers to extend that by plugging state into a `private_data` member.

Since the original design, support for `LicenseInfo` subclasses was
added, largely removing the need for `private_data`. In practice,
though, the `LicenseInfo` dataclass could not be extended with new
required arguments due to the way that the dataclass was registered.
By default, dataclasses register fields as positional arguments instead
of keyword-only arguments, and this means that any field registered
after the last field with a default must itself have a default, even in
subclasses. This isn't ideal for this purpose.

To help facilitate License Provider backends with custom state, we now
register the dataclass with `kw_only=True`, and remove `private_data`.

Going forward, we should ensure that all dataclasses use `kw_only=True`
to help with forward-compatibility and extensibility.

     


    		
    d32f241fc16c3c8db291f6786813f703474c57f4

   




   


    

    

     

      Remove LicenseInfo.private_data and help extensibility.
      
Originally when the new licensing code was added, the intent was to back
license representations by a `LicenseInfo` and to allow license
providers to extend that by plugging state into a `private_data` member.

Since the original design, support for `LicenseInfo` subclasses was
added, largely removing the need for `private_data`. In practice,
though, the `LicenseInfo` dataclass could not be extended with new
required arguments due to the way that the dataclass was registered.
By default, dataclasses register fields as positional arguments instead
of keyword-only arguments, and this means that any field registered
after the last field with a default must itself have a default, even in
subclasses. This isn't ideal for this purpose.

We can't use `kw_only=True`, since that's only available on Python 3.10
and higher, and there's no getting around the internal logic that
impacts subclasses. Plus, dataclasses are slow and truly necessary, just
a convenience.

So to help facilitate License Provider backends with custom state, and
avoid the dataclass issues, this has been converted to a standard class.
This will also make it easier for subclasses to override it in a
consistent way without having to tie into the dataclass-specific
post-construction hooks.

     


    		
    9982f25aa7714bd7119795589848679e127073e2

   



  
 







   

  





  

   

    Diff:
   

   

    
 Revision 2 (+236 -66)
Show changes
 
    reviewboard/licensing/license.py 
 

   

  











 

  
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david




   

   







  

 



 

  


   

   

    
 
david



    
   


  

  

  



    




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    Ship It!
    
  
    
 
    

 
    
  


    
 
    
 
      

  

 
    


    

 
    

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maubin




   

   







  

 



 

  


   

   

    
 
maubin



    
   


  

  

  



    




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    Ship It!
    
  
    
 
    

 
    
  


    
 
    
 
      

  

 
    


    

 
    

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