Re: mailcap viewers in dired; gnus-dired.el, mailcap.el

[Juri Linkov]

>     > `!' (`dired-do-shell-command') is not exactly what
>     > `gnus-dired-find-file-mailcap' does.  In mailcap.el you can also
>     > specify Emacs-internal handling, IIRC.
>
>     This is an interesting problem.  It seems that Emacs-internal handling in
>     mailcap-mime-data mostly duplicates auto-mode-alist, isn't it?
>
> If this is a matter of deciding how to handle an attachment based on
> its mime type, I do not see that as redundant with `auto-mode-alist'.
> That decides how to handle a file based on its name.  A file does
> not carry anything with it analogous to a stated mime type.
> You only have the file name and the data (magic numbers).

The mailcap feature contains two basic parts:

1. file extension to the mime type mapping (e.g. ".pdf" -> "application/pdf"),
2. mime type to the view command name mapping (e.g. "application/pdf" -> 
"xpdf").

But also it allows mappings from the mime type to the Emacs function
(e.g. "application/pdf" -> `doc-view').

For Gnus attachments these types are necessary, and perhaps we should add
now the `doc-view' mappings for PDF/PS/DVI mime types to mailcap.el,
because I think viewing PDF/PS/DVI attachments is more preferable than
running an external program.

In the latest patch Tassilo added a new `auto-mode-alist' mapping
from .pdf/.ps/.dvi to `doc-view-mode', and I think this is right because
this is for visiting a file in Emacs, not an attachment in Gnus.

BTW, I don't understand why .eps is removed from `auto-mode-alist' in the
latest patch?

-- 
Juri Linkov
http://www.jurta.org/emacs/