Re: String concatenation design


"Risto Lankinen" <rlankine@xxxxxxxxxxx> wrote in message
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"Anton Treuenfels" <atreuenfels@xxxxxxxxxxxxx> wrote in message
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Now I am considering how best to add string concatenation. The problem
isn't
so much how to actually concatenate strings (that's easy) but how to
allow
the operation to be expressed.

[...]

2) use no operator. Imply concatenation by adjacent strings. "A" "B" ->
"AB"

3) pick a currently unused symbol (or one that only appears in some
non-conflicting context) to use as the concatenation operator. But what
might be a good, easily remembered choice? "&", maybe?

Do you allow string variables? If all strings are literals, then I would
choose option 2) [which begs a question: why is concatenation needed
anyway]. If you do allow string variables then I would choose option
3) and use the ampersand "&" for concatenation.

Presently all strings are literals but not necessarily constants :) The
expression analyzer is part of a macro assembler and macro argument
substitution can change the value of a string literal during macro expansion
(I get to write the rules, so I permit this!).

In assembly languages opcode argument expressions sometimes contain, for
example, address mode information as well as numeric. I want to be able to
massage such expressions before passing them to the analyzer, rather than
tying the analyzer to one particular assembly language. More particularly I
want to be able to provide that facility at the user level as part of an
effort to make the assembler more customizable.

But obviously string variables are a reasonable extension.


.

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