Re: What is the type of user input?

[Kevin Rodgers <ihs_4664@yahoo.com>]

Hattuari wrote:
 > Kevin Rodgers wrote:
 >>gl-type is a string.  Since the paste-gl-type-map property list is keyed
 >>by symbols, plist-get returns nil.
 >
 > That's what I was missing.  I was assuming that 'symbol-name implicitly
 > meant symbol would evaluate to a string.  Now that I've read the first
 > several chapters of the Elisp Reference Manual, I have a better idea of
 > what's going on.

'foo is equivalent to (quote foo), which is the symbol whose name is
"foo".

The symbol-name name function takes a symbol and returns its name
string, and the intern function takes a string and returns the symbol
with that name.

 >>The %s message specifier can be
 >>applied to any Lisp object, and symbols and strings are formatted the
 >>same.
 >>
 >>The solution is to either (1) read gl-type with the %S code or (2) call
 >>plist-get with (intern gl-type).
 >
 > I opted for trying an association array, which also worked.

I assume you mean association list.  But whether you have a (KEY-1
VALUE-1 ... KEY-N VALUE-N) property list where they keys are by
definition symbols or a ((KEY-1 . VALUE-1) ... (KEY-N . VALUE-N)) alist
where the keys can be arbitrary lisp objects, you still have to make
sure that you pass a key of the correct type to plist-get or assoc,
respectively.

 > I will try your suggestion of using (intern gl-type).  As for reading
 > gl-type with %S, I'm not sure what that would do for me.  The only use
 > I know for that is to use it in a string format.

Oops, I meant S.  (You used s in the interactive spec to read gl-type as
a string; using S would bind gl-type to the intern'ed symbol.)

 >> > OTOH, when I evaluate this expression in an emacs-lisp buffer
 >> > (paste-gl-array 'GLbyte 4 'v), I see the following in the echo area:
 >> >
 >> > gl-type=GLbyte, gl-components=4, gl-vector=v , suffix=b
 >> >
 >> > That is the desired result.  Why is this not the result of calling the
 >> > function as an interactive command as described above?
 >> >
 >> > I will continue to look for an answer in the documentation, but any
 >> > help from someone who knows the answer would be appreciated.
 >>
 >>It's not that hard to find:
 >>
 >>`C-h f message' has a link to the doc string for `format', which has a
 >>link to the doc string for `princ' in its description of %s:
 >>
 >>,----[ C-h f princ RET ]
 >>| princ is a built-in function.
 >>| (princ OBJECT &optional PRINTCHARFUN)
 >>|
 >>| Output the printed representation of OBJECT, any Lisp object.
 >>| No quoting characters are used; no delimiters are printed around
 >>| the contents of strings.
 >>|
 >>| OBJECT is any of the Lisp data types: a number, a string, a symbol,
 >>| a list, a buffer, a window, a frame, etc.
 >>|
 >>| A printed representation of an object is text which describes that
 >>| object.
 >>...`----
 >
 >
 > That doesn't tell me anything that I see as addressing my problem. 
Can you
 > explain how that answers my question as to why the two symbols were not
 > comparing as I had expected?

You assumed that since the symbol and the string looked the same when
displayed in the echo area by (message "%s" ...), that they were
actually the same.  The message -> format -> princ doc strings explain
that a symbol and its name string will be displayed the same by (message
"%s"), even though they are different objects of different types.

 >  (type-of gl-type) was what showed me what I was doing wrong.  I tried to
 > post back to the newsgroup, but my ISP was down.

-- 
Kevin Rodgers