RE: [PATCH] Add new function to test whether a key is present in a hash table.

[Drew Adams <drew.adams@oracle.com>]

> DA> 2. The function name should have `key' in it, I think. Suggestion:
> DA> `hash-table-contains-key-p' or even just `hash-table-key-p'.
> 
> It seems a bit strange that the name isn't something like "hashash",
> since knowing "puthash" and "gethash" would never help you guess
> hash-table-contains-key-p.

Right.  And knowing `hash-table-contains-key-p' wouldn't
help you guess `puthash' or `get-hash'.

But that's the fault of `puthash' and `gethash'. ;-)

It's `puthash' and `gethash' that are not so conventional
for Emacs.  They are borrowed from Common Lisp.  Likewise,
`maphash', `remhash', and `clrhash'.  Those names predate
Common Lisp even.

`puthash', `gethash', `remhash', etc. could be made
aliases of, say, `hash-table-put', `hash-table-get',
`hash-table-remove', etc.  (I'm not saying they should.)

`puthash' seems to be the only Emacs `put*' function
whose name doesn't start with `put-' (apart from `put'
itself).  Same thing for `gethash' (except that there
are also `getenv' and `getf').  The Emacs convention is
to use prefix `put-' or `get-'.

Another (more common?) convention in Emacs is to put the
object type first: `string-match', `bool-vector-union',
`mode-line-next-buffer', `menu-bar-open', `marker-buffer',
`buffer-size', `window-child', `frame-edges', etc.,
especially for functions that extract parts of an object.

Yet another convention is to put the verb first,
especially for "utility" verbs: `map-*', `make-*',
`put-*', `get-*', `copy-*', `delete-*', etc.

Finally, a library prefix is often used: `ad-get-*',
`ange-ftp-get-*', `bookmark-get-*', `comint-get-*',
`dired-get-*', `ediff-get-*', `gnus-get-*' ...


These are the functions I see with "hash" in their names:

0. Those that (I guess) have nothing to do with hash tables:

   ange-ftp-guess-hash-mark-size
   ange-ftp-process-handle-hash
   buffer-hash
   gnutls-hash-digest
   hashcash-insert-payment
   hashcash-insert-payment-async
   hashcash-verify-payment
   rfc2104-hash
   sxhash
   sxhash-eq
   sxhash-eql
   sxhash-equal

   I mention these to point out that names like `puthash'
   don't really, on their own, make clear that they have
   to do with a hash table.

1. Those that are about hash-table hashing but (I guess)
   don't have a hash table as the main object:

   gnus-create-hash-size
   gnutls-hash-mac
   secure-hash
   secure-hash-algorithms

2. Those (non-CL) that have a hash table as the main object:

   ange-ftp-hash-entry-exists-p
   ange-ftp-hash-table-keys
   clrhash
   copy-hash-table
   define-hash-table-test
   define-translation-hash-table
   gethash
   gnus-make-hashtable
   hash-table-count
   hash-table-p
   hash-table-rehash-size
   hash-table-rehash-threshold
   hash-table-size
   hash-table-test
   hash-table-weakness
   make-hash-table
   maphash
   puthash
   remhash
   ucs-normalize-make-hash-table-from-alist

3. Common-Lisp emulation functions for hash tables:

   cl-clrhash
   cl-gethash
   cl-hash-table-count
   cl-hash-table-p
   cl-make-hash-table
   cl-maphash
   cl-not-hash-table 
   cl-puthash
   cl-remhash

   Note that except for those names inherited from older
   Lisps, Common Lisp spells out `hash-table' in the
   function names.

The most common convention, so far, for Emacs hash-table
functions is to start the function name with `hash-table'.
That accords with the convention of putting the object
name first.