I like ${hex:<hex>}, because it looks like a function and we can use the
same syntax for other string expansions, too.
I think it only looks like a function to you because you're used to
exim.conf :-) if you know of other languages where functions looks like
this, I'm interested in hearing about it.
Yes and no. :) Yes: It IS familar, because I use Exim, and I know of no
other language using that notation. No: Seen from an abstract point
of view, a variable and a function call differ only in some syntactic
element that specifies arguments, because both deliver a rhs value
(assuming strict evaluation).
That's why I like to keep function calls very close to variables.
If you dislike the colon, I don't mind exchanging that against some other
token, as long as it is not in the follow-set of the variable identifier
in the variables extension.
I like ${...}, because it specifies the borders of "magic inside".
All the magic we currently have are variables, but that does not mean
things have to stay that way.
Michael