Re: [RFC PATCH v2 3/6] doc: Add namespace collision guidelines file

From: Junio C Hamano <gitster@pobox.com>
Date: May 28, 2020, 18:49 UTC
Message-ID: <xmqqy2pb3new.fsf@gitster.c.googlers.com>
In-Reply-To: <20200525232727.21096-4-keni@his.com>

Kenneth Lorber <keni@his.com> writes:

Show 8 quoted lines

> +Git uses identifiers in a number of different namespaces:
> +
> +* environment variables
> +* files in $GIT_DIR
> +* files in the working trees
> +* config sections
> +* hooks
> +* attributes

The names of the subcommands "git" can spawn is a shared resource. You can install "git-imerge" program in one of the directories on your $PATH and say "git imerge" to invoke the program.

Two third-party developers may have to coordinate to avoid giving the same name to their totally-unrelated tools, if they hope that both of their tools to be useful in the larger Git ecosystem.

> +In order to reduce the chance of collisions between names Git uses
> +and those used by other entities (users, groups, and extension authors),
> +the following are recommended best practices.

OK.

> +Names reserved to Git:

s/to/by/ perhaps.

> +Names reserved for individual users:
> +
> +* The directory `$GIT_DIR/my`

So an individual user is allowed to store anything in that directory, and "git" or any third-party tools won't care. OK.

> +* Environment variables starting with `GIT_MY_`

Likewise. But then the users can use MY_FOO_BLAH without GIT_ prefix in the first place, so there isn't much gain there. Downside for "git" and third-party tool authors is not so big (just the loss of a single prefix "_MY"), so perhaps it is OK.

> +* Configuration section `my`
> +* Files or directories in `$GIT_DIR/hooks` starting with `my_`
> +* Attributes starting with `my_`

The last one does not make much sense. You have to forbid defining my_attributes in .gitattributes files that are tracked in-tree; otherwise I cannot work with you on the same project, because I cannot use my_attributes for my own purpose in that project. For the same reason, reserving attributes for individual repositories does not make much sense, either.

> +Names reserved for individual repos:
> +
> +* The directory `$GIT_DIR/this`

It is unclear what it means to have $GIT_DIR/my and $GIT_DIR/this and how to choose which one of these two ought to be used for each occasion a user finds a need to store something in these places.

> +* Environment variables starting with `GIT_THIS_`

The utility of this one is dubious.

	$ export GIT_THIS_BLAH=value
	$ cd repo1 ; work work work
	$ cd ../repo2 ; work work work

Unless you arrange to reset GIT_THIS_* environment variable every time you visit a separate repository, it would not be pratical to use.

> +Names reserved for the lowest level group of people:

What's lowest level group of people?

Also, where did the guideline for third-party tools go?

At this point I need to say that this is not very well thought out (yet), or that this is not very well explained, or perhaps both, so I'll stop commenting on it for now.

Thanks.