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Re: Using append to create a list from a line of text
From: |
Pascal J. Bourguignon |
Subject: |
Re: Using append to create a list from a line of text |
Date: |
Tue, 16 Apr 2013 22:51:00 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.2 (gnu/linux) |
acomber <deedexy@gmail.com> writes:
> I want to create a list of words from a line of text delimitted by tabs. I
> want to basically split the line into atoms, split by tab.
>
> The code below is sort of pseudocode but is this the best approach to do
> this type of thing?
>
> Here is my first attempt:-
>
> (defun get-hdr()
> ;obviously point must be positioned on correct line
> (let (mylist)
> while(not (end-of-line)
> while(re-search-forward ("[A-Za-z]+[^\t\n]" nil t)
> append (match-string 1) mylist
> )
> )
> )
> )
Nice, but it's not formatted correctly. I'd avise you to use
paredit-mode.
Adding and removing newlines where one should, and letting emacs indent
the sexp, we get this text:
(defun get-hdr()
;; obviously point must be positioned on correct line
(let (mylist)
while
(not (end-of-line)
while
(re-search-forward ("[A-Za-z]+[^\t\n]" nil t)
append
(match-string 1)
mylist))))
Now, two obvious things:
1- undefined variable named `while'. Where does that variable come
from?
2- the function `not' is passed three arguments, when it expects only
one!
3- "[A-Za-z]+[^\t\n]" is not a symbol naming an operator, nor is it a
lambda expression, therefore the sexp ("[A-Za-z]+[^\t\n]" nil t) is
not a lisp form.
4- undefined avariable named `append'.
5- while re-search-forward takes optionally up to four arguments, I
doubt that mylist is bound to the count of searches to do, or that
(match-string 1) returns whether you want or not to signal errors if
no match is found.
> How do I get my function to return the list, mylist?
Try to read a lisp tutorial again. On the first chapter, the basic
syntactic elements are always presented. You should have no problem
understanding them and correcting your code.
--
__Pascal Bourguignon__ http://www.informatimago.com/
A bad day in () is better than a good day in {}.