[Distutils] PEP 376, the INSTALLER file, and system packages

[Ian Cordasco]

On Fri, Jan 22, 2016 at 12:10 PM, Donald Stufft <donald at stufft.io> wrote:
> PEP 376 added a file to the .dist-info directory called "INSTALLER" which was
> supposed to be:
>
>     This option is the name of the tool used to invoke the installation.
>
> However, nothing has really ever implemented it and it's gone largely ignored
> until just recently pip 8.0 started writing the INSTALLER file into the
> metadata directories with a value of "pip".
>
> I'd like to propose adding a special cased value to add to the installer file
> that will tell projects like pip that this particular installed thing is being
> managed by someone else, and we should keep our hands off of it. According to
> PEP 376 the supported values for this file are r"[a-z0-9_-.]", however I think
> since nobody has ever implemented it, we could expand that so that it so you
> can also have a special value, of "dpkg (system)" or maybe that's not worth it
> and we could just have "system" as a special value.

Why not use something like JSON to allow us to have a little more
information about the installer, e.g.,

{"name": "pip", "system": true, ...}

> The benefit of doing this, is that with a special value in that file that says
> "this file belongs to the OS", then pip could start looking for that file and
> require a --force flag before it modifies any files belonging to that project.
> Then distributors like Debian, Fedora, etc could simply write out the INSTALLER
> file with the correct value, and pip would start to respect their files by
> default.
>
> Thoughts? Does this sound reasonable to everyone? Do we think it needs a new
> PEP or can we just amend PEP 376 to add this extra bit of information?

I think amending the PEP makes sense.