Generating generations of files

DL Neil PythonList at DancesWithMice.info
Mon Apr 29 19:27:02 EDT 2019


On 30/04/19 9:04 AM, Peter J. Holzer wrote:
> On 2019-04-29 20:12:28 -0000, Grant Edwards wrote:
>> On 2019-04-29, DL Neil <PythonList at DancesWithMice.info> wrote:
>>> Are you aware of a library/utility which will generate and maintain the
>>> file names of multiple generations of a file?
>>
>> Well, the FILES-11 filesystem on VAX/VMS did that automatically, but
>> that's probably not too helpful. Though I guess Python is actually
>> available for OpenVMS, and the porting of OpenVMS to AMD64 (aka
>> x86-64) is progressing: https://www.vmssoftware.com/updates_port.html
> 
> Until this is finished you could use something like this:
> 
> #!/usr/bin/python3
> 
> import os
> 
> def open11(file, mode, **kwargs):
>      if "w" in mode:
>          try:
>              oldfile = os.readlink(file)
>              basename, version = oldfile.split(";")
>          except FileNotFoundError:
>              basename = os.path.basename(file)
>              version = 0
>          newfile = basename + ";" + str(int(version) + 1)
>          os.unlink(file)
>          os.symlink(newfile, file)
>      return open(file, mode, **kwargs)
> 
> 
> if __name__ == "__main__":
>      with open11("foo", "w") as f:
>          f.write("test1")
> 
>      with open11("foo", "w") as f:
>          f.write("test2")
> 
>      with open11("foo", "w") as f:
>          f.write("test3")
> 
> :-)
> 
> (WARNING: I haven't really tested this)


Didn't think of the concept of using links!

As Eli showed, with a bit of refinement, we can make something from here...

Thanks!
-- 
Regards =dn


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