gmane.comp.mathematics.maxima.general

reading a string from keyboard

Hi,

I just recently noticed that readline(true) (or readline(false)) no 
longer reads a string from the keyboard (stdin). It used to work before 
5.15 - probably this was not the correct way of doing it but couldn't 
figure out anything else at that time. Note that I want to read a string 
- not expression. This string can be, for example, a path name which is 
not a valid expression obviously.

After testing a bit, I found out that the following seems to work now:

readline(?\*standard\-input\*)

where the stream refers to the corresponding lisp stream name that 
points to standard input. This also works well with wxmaxima (which 
communicates via pipes I suppose). Is this the right way of doing this? 
Meaning that is it standard enough that it should work with future 
maxima releases as well.

It might be a good idea to include the pre-existing stream names that 
are accessible in maxima in the manual - the previous one was
not trivial to figure out.

Jussi Eloranta
Cal State Northridge

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van Nek | 6 Sep 11:29

Re: reading a string from keyboard


Hi,

when I load an old version of stringproc.lisp I can reproduce, that readline(true) and 
readline(false) worked somehow. 
Entering readline(true); makes Maxima appear to hang, but you had been able to type in 
characters behind it:

(%i1) load("H:/Programme/Maxima-
5.14.0/share/maxima/5.14.0/share/contrib/stringproc/stringproc.lisp")$
(%i2) stringdisp:true$
(%i3) readline(true);  qwe qwe;
(%o3)                            "  qwe qwe;"

Readline was designed to read from streams from files opened by the openr function. The 
actual version of stringproc.lisp errors if the stream is not regarded as a stream on Lisp 
level. So it errors if you use true or false. 

For reading from the standard input you can use the function read:

(%i4) read("my text");
my text 
"qwe QWE Qwe";
(%o4)                            "qwe QWE Qwe"
(%i5) stringp(%);
(%o5)                                true

Two remarks:
1. read without argument shows the same behaviour as the above described for the old 
readline. It seems to hang. I regard this as a bug.

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