Re: set variable

[Robert Kubosz]

Aaron, thank you!

This is something I was looking for.

On 19.02.2021 21:42, Aaron Hill wrote:
> On 2021-02-19 12:21 pm, Robert Kubosz wrote:
> > Hello
> >
> > The default way to override an existing variable in scheme is:
> > #(define foo 2)
> > #(set! foo 3)
> > #(display foo) %--> output is 3
> >
> > I want to override the foo with use of another variable storing the
> > foo's varname:
> >
> > #(define foo 2)
> > #(define bar 'foo) %variable storing the foo's varname
> > #(set! `,bar 3)  %I want here to override the foo variable with use 
> > of bar
> > #(display foo) %---> the expected by me output is 3
> >
> > How can I do this?
>
> The set! macro expects the variable to be changed.  On the other hand, 
> module-set! expects a symbol naming the variable to be changed.  If 
> you know the variable is within the current-module, you can do this:
>
> %%%%
> \version "2.22.0"
>
> #(define xyzzy 123)
> #(format #t "\nxyzzy = ~s" xyzzy)
> #(set! xyzzy -456)
> #(format #t "\nxyzzy = ~s" xyzzy)
> #(module-set! (current-module) 'xyzzy 78.9)
> #(format #t "\nxyzzy = ~s" xyzzy)
> %%%%
> ====
> Parsing...
> xyzzy = 123
> xyzzy = -456
> xyzzy = 78.9
> Success: compilation successfully completed
> ====
>
>
> -- Aaron Hill