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Re: set variable

From: Aaron Hill
Subject: Re: set variable
Date: Fri, 19 Feb 2021 12:42:23 -0800
User-agent: Roundcube Webmail/1.4.9

On 2021-02-19 12:21 pm, Robert Kubosz wrote:

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)
xyzzy = 123
xyzzy = -456
xyzzy = 78.9
Success: compilation successfully completed

-- Aaron Hill

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