customizing mm-charset-synonym-alist (was: nail uses iso8859-1 instead of iso-8859-1)

[Reiner Steib <reinersteib+gmane@imap.cc>]

On Thu, Apr 26 2007, Katsumi Yamaoka wrote:

> I've also made it use defcustom, so you can now customize the alist
> easily.

I think this is not a good idea.

1. `mm-charset-synonym-alist' is modified by mm-setup-codepage-*, so a
   user will see "CHANGED outside Customize; operating on it here may be
   unreliable."

,----
| ;; Initialize:
| (mm-setup-codepage-iso-8859)
| (mm-setup-codepage-ibm)
`----

2. The initial value depends on the availability of charsets (lots of
   `mm-coding-system-p's).  So it will change when using different
   Emacs versions and flavors.  But if the user has customized it,
   this conditionals are eliminated.

IMHO, if we want a customizable variable, we should create a new
variable (default: nil) and construct `mm-charset-synonym-alist' from
the new one, `mm-codepage-iso-8859-list' and `mm-codepage-ibm-list'
(using mm-setup-codepage-*).  A new setup function should check if the
cdr of each element is a valid charset and add it to
`mm-charset-synonym-alist'.


BTW, if former defvars are changed to defcustoms, the :version is the
one when it's made customizable, not when the defvar was introduced.
So ":version "21.1" is not correct.

Bye, Reiner.
-- 
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      (o o)
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