RE: tool to display library dependencies?

[Drew Adams]

     > Is there a tool somewhere that will look at one or more Emacs Lisp
     > libraries and output a tree or list of its library dependencies?
     > And it would be good if such a tool/command distinguished somehow
     > between hard and soft (`(require nil t)') `require's.

    C-h f file-requires
    C-h f feature-file

This is great news. I wasn't aware of these functions (or of loadhist.el).

    (require 'loadhist)
    (defun file-dependencies (file)
       "Return a list of the files `require'd by FILE.
    If any of those files themselves `require' another, return it as a list
    of it and its dependencies, and so on (recursively)."
       (mapcar (lambda (feature)
                 (let* ((required-file (feature-file feature))
                        (required-file-dependencies
                         (file-dependencies required-file)))
                   (if required-file-dependencies
                       (cons required-file required-file-dependencies)
                     required-file)))
               (file-requires file)))

    (progn (require 'w3m) (file-dependencies "w3m"))
    returns ("browse-url" "timezone" "w3m-hist" ("w3m-e21" "wid-edit"
            ("w3m-ccl" "ccl") "w3m-fsf" "w3m-favicon" "w3m-image")
            "w3m-proc" "w3m-util")

Thanks, Kevin.

However, there is one hiccup still: there is no distinction between hard and
soft `require's. This in effect relies on all of the `require'd libraries
actually being loaded.

For example, I have a library foo.el that does this: (require 'mwheel nil
t). My library works in Emacs 21 (which has feature mwheel), but also in
Emacs 20 (which does not have feature mwheel) - the soft require succeeds in
Emacs 21 and fails (gracefully) in Emacs 20.

When I try (progn (require 'foo) (file-dependencies "foo")) in Emacs 20 I
get an error from the call to (feature-file mwheel): "mwheel is not a
currently loaded feature".

This is such a _useful_ feature, and it's so close to being generally
usable. I can try myself to hack it up to get around this, but perhaps you
have a suggestion or two (or a fix)?

Thanks,

  Drew