[Distutils] Useless field (was Re: Finishing PEP 345)

["Martin v. Löwis"]

> The question "what it it for?" needs a better answer than that.  Who
> looks at this field?  What do they do with the data that it contains? 
> When creating a record, how do I know the correct value to put in this
> field?  Can I just make up anything, like "Supported-Platform: my new
> laptop"?

The spec says

"The semantics of the Supported-Platform field are not specified in this
PEP."

which answers all these questions: people will look at the field, and
proprietary software may do so as well. What they do with the data is
out of scope of the PEP. Any value is correct. You can certainly put
"my new laptop" into the field.

Now, you may not *like* that specification. However, it is fairly clear.

> Useful for me to understand why I should bother the fill in this field. 

If you know it's primarily for a human reader (as the text says), you
should also know whether you can bother to fill in the field.

It depends on your package, of course: for some package,
supported-platform may be useful, for others, it may not.

> Useful for me to understand why it is in the specification in the first
> place.

This is also (implicit) in the specification: it's a compromise. Without
knowing the history, it seems that some party wanted such a field, and
another party didn't think it was feasible or reasonable to provide.
Hence the compromise.

Notice that "uninterpreted data" is not unheard of as a concept:
Summary, Description, Keywords, Author, Maintainer are all of the
same kind.
> 
> You imply that this field is not intended to be machine processable. 
> That means that:
> 
> - packaging tools will not look at it, because the tools don't know what
> it means

Correct.

> - database searches of available packages will not look at it, because
> the databases don't know what it means

I don't know where you get that implication from. By the same reasoning,
the database search wouldn't look at Summary or Description. I can
assure you that they do.

> In that case, it is as simple as adding "This field is intended only as
> a hint to a human reader about the build environment.  Because there is
> no specification for the content of this field, it does not make sense
> to do searches or comparisons on this field.  When writing a new record,
> put whatever descriptive text about the platform that you think might be
> useful."
> 
> If that is a correct description, then that description should go in the
> PEP.

I wouldn't mind it being added. However, the wording that is currently
there already says exactly that (and more).

Regards,
Martin