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(emacs-lisp-intro.info)Several defuns

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Count Several `defuns' Within a File
====================================

   A file such as `simple.el' may have 80 or more function definitions
within it.  Our long term goal is to collect statistics on many files,
but as a first step, our immediate goal is to collect statistics on one
file.

   The information will be a series of numbers, each number being the
length of a function definition.  We can store the numbers in a list.

   We know that we will want to incorporate the information regarding
one file with information about many other files; this means that the
function for counting definition lengths within one file need only
return the list of lengths.  It need not and should not display any
messages.

   The word count commands contain one expression to jump point forward
word by word and another expression to count the jumps.  The function
to return the lengths of definitions can be designed to work the same
way, with one expression to jump point forward definition by definition
and another expression to construct the lengths' list.

   This statement of the problem makes it elementary to write the
function definition.  Clearly, we will start the count at the beginning
of the file, so the first command will be `(goto-char (point-min))'.
Next, we start the `while' loop; and the true-or-false test of the loop
can be a regular expression search for the next function definition--so
long as the search succeeds, point is moved forward and then the body
of the loop is evaluated.  The body needs an expression that constructs
the lengths' list.  `cons', the list construction command, can be used
to create the list.  That is almost all there is to it.

   Here is what this fragment of code looks like:

     (goto-char (point-min))
     (while (re-search-forward "^(defun" nil t)
       (setq lengths-list
             (cons (count-words-in-defun) lengths-list)))

   What we have left out is the mechanism for finding the file that
contains the function definitions.

   In previous examples, we either used this, the Info file, or we
switched back and forth to some other buffer, such as the `*scratch*'
buffer.

   Finding a file is a new process that we have not yet discussed.