Docstrings and manuals, was: Re: bug#20637: incompatible, undocumented change to vc-working-revision

[Dmitry Gutov <dgutov@yandex.ru>]

On 04/15/2016 04:23 PM, Michael Albinus wrote:

>> I disagree. The manual is the documentation for the users, to explain
>> in depth, give examples, et cetera. The docstrings and VC's internal
>> documentation have to stand on their own. It would be silly if the
>> difference between `vc-backend' and `vc-responsible-backend' were to
>> only be explained in the manual, but not in the docstrings.
>
> Are we speaking about different manuals? I'm speaking about the ‘GNU
> Emacs Lisp Reference Manual’, and not the ‘GNU Emacs Manual’ (the manual
> dedicated to users).

OK, so the Emacs Lisp Reference is a counter-example. And it contains a 
narrative that explains different aspects of Emacs Lisp in a sort-of 
seamless fashion, which is great, because there's no good way to do that 
with just docstrings.

And then it goes ahead and provides its own versions of descriptions for 
functions and variables that are different from the docstrings, and are 
often longer, but sometimes shorter (e.g. for `obarray'), and at times 
it seems like the only reasons for the existence of the two versions is 
to have docstrings in the imperative voice, and the pieces of text in 
the manual, in the passive voice.

And then the two versions start to diverge. For instance, the docstring 
for `mapatoms' is rather short. The manual entry for it is longer, *and* 
it documents that `mapatoms' returns nil. Why would someone put that 
piece of information into the manual, but not the docstring, is beyond me.

So, to be clear, I dislike the ambiguity that manuals that try to be 
all-encompassing, like this one, create about the main source of 
information about each function.