Re: mkstemp strange behavior

[R. Mattes]

On Wed, 2005-08-10 at 13:54 -0400, Alan Grover wrote:
> I ran into this too. My reasoning was something like:
> 
> The string, "/tmp/XXXXXX" is constructed at reader time. So, there is
> exactly one string. The "let" creates a new variable each time you call
> "test", but the variable is bound to the same string.

Besides: string constants (i.e. "xxx" stuff) are _inmutable_ in scheme.

> Mkstemp modifies the (one and only) string the first time.

Yes, modifying a constant is not a good idea (and guile should croack 
allready the first time).

 Just my 0.02$
  
 Ralf Mattes

> If you force the value to be computed at exec time, the problem should
> go away: (string-append "" "/tmp/XXXXXX").
> 
> You could test my theory by something like:
> 
> (define (test) (let ((filename "/tmp/XXXXXX")) filename))
> 
> (display (eq? (test) (test)))
> 
> Which yields #t for me. And, (eq? "/tmp/XXXXXX" "/tmp/XXXXXX") yields
> #f, for comparison.
> 
> José Roberto B. de A. Monteiro wrote:
> > Hello all!
> > 
> > I was trying to use mkstemp! in my program, instead of tmpnam, but I have no
> > success... I mkstemp! is getting me confused. It alters original string, so
> > we can easely have the name of temporary file.
> > 
> > But, with following code, I suposed it would work, but it is reusing an old
> > string:
> > 
> > #!/usr/bin/guile \
> > -s
> > !#
> > 
> > (define (test)
> >   (let ((filename "/tmp/XXXXXX")
> >         (tmp #f))
> >     (format #t "before: filename=~A\n" filename)
> >     (set! tmp (mkstemp! filename))
> >     (format #t "after : filename=~A\n" filename)
> >     (close tmp)))
> >       
> > (format #t "First call...\n")
> > (test)
> > (format #t "Second call...\n")
> > (test)
> >                       
> > And the result of this code is:
> > 
> > First call...
> > before: filename=/tmp/XXXXXX
> > after : filename=/tmp/HGLPtZ
> > Second call...
> > before: filename=/tmp/HGLPtZ
> > ERROR: In procedure mkstemp!:
> > ERROR: Invalid argument
> > 
> > I can not figure out why the string is not set to /tmp/XXXXXX in the second
> > call...
> > 
> > Some help!?
> > 
> > Regards
> > Betoes
> > 
> > 
> > _______________________________________________
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> > 
> 
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