tool to display library dependencies?

tool to display library dependencies?

[Drew Adams]

This has probably been asked before, but I couldn't find it.

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? An Emacs command that
does this would be great.

For example: Library A requires B, which requires C and D. I'd like to be
able to determine all of the libraries that A ultimately requires - in this
case B, C, and D. A dependency tree would be even better:

 A-B-+-C
     |
     +-D

I realize that it would be problematic to take autoloads into account, but
just dealing with the explicit `require's would still be useful. And it
would be good if such a tool/command distinguished somehow between hard and
soft (`(require nil t)') `require's.

 - Drew

Re: tool to display library dependencies?

[Kevin Rodgers]

Drew Adams wrote:
 > This has probably been asked before, but I couldn't find it.
 >
 > 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? An Emacs 
command that
 > does this would be great.
 >
 > For example: Library A requires B, which requires C and D. I'd like to be
 > able to determine all of the libraries that A ultimately requires - 
in this
 > case B, C, and D. A dependency tree would be even better:
 >
 >  A-B-+-C
 >      |
 >      +-D
 >
 > I realize that it would be problematic to take autoloads into 
account, but
 > just dealing with the explicit `require's would still be useful. 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 RET ]
| file-requires is a compiled Lisp function in `loadhist'.
| (file-requires FILE)
|
| Return the list of features required by FILE.
`----

,----[ C-h f feature-file RET ]
| feature-file is a compiled Lisp function in `loadhist'.
| (feature-file FEATURE)
|
| Return the file name from which a given FEATURE was loaded.
| Actually, return the load argument, if any; this is sometimes the name 
of a
| Lisp file without an extension.  If the feature came from an 
`eval-buffer' on
| a buffer with no associated file, or an `eval-region', return nil.
`----

So:

(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)))

Now (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")

-- 
Kevin Rodgers

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

Re: tool to display library dependencies?

[Kevin Rodgers]

Drew Adams wrote:
 > 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)?

Sure, just conditionalize the lambda body:

(if (featurep feature)
     (let*
       ...)
     feature)

That will yield a feature symbol instead of a file name string for all
features that were not actually loaded.

-- 
Kevin Rodgers