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From: Lawrence D'Oliveiro <ldo@nz.invalid>
Newsgroups: comp.lang.misc
Subject: Re: String-Based Macro Systems
Date: Sat, 13 Apr 2024 05:51:27 -0000 (UTC)
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On Sat, 13 Apr 2024 05:09:26 -0000 (UTC), Blue-Maned_Hawk wrote:

> Whenever a system has a system to escape symbols, there are two ways to
> go about it:  either the symbol is magic by default, and the escape
> makes it normal, or the symbol is normal by default, and the escape
> makes it magic.

And here’s another question: is magic iterative? Is text produced by a 
macro substitution automatically subject to further macro substitutions?

This is true of Macrogenerator and m4, but perhaps this is a source of a 
lot of the problems with string-based macro systems.

On the other hand, if you didn’t do this, then how would you implement the 
example I gave?

 §DEF,AORB,<§§Q;;>,§DEF,A,<A§UPDATE,Q,B;>;,§DEF,B,<B§UPDATE,Q,A;>;;

If “§A;” expands literally to “A§UPDATE,Q,B;” with no further special 
interpretation of the embedded “§”, then how would you explicitly request 
invocation of the “UPDATE” function?

The answer would be, the body of the macro would not directly be 
interpreted as literal text, but would have to consist of a sequence of 
explicit directives, like “insert literal text”, “insert expansion of a 
further macro” and so on.