trigraphs in X3J11

[T. William Wells]

In article <5215 at ico.ISC.COM>, rcd at ico.ISC.COM (Dick Dunn) writes:

> [lots of stuff demonstrating how trigraphs break existing code].

>     Replacing all the nasty characters with corresponding trigraphs gives:
>
>       if (line??(0??)=='??=' ??!??! line??(0??)=='%') ??<
>               prepro(&line??(1??));
>               linect++;
>       ??>

Ugh.  How horrible.  However, I imagine that few programmers will
actually have to cope with this.  As you suggest, the effort of
using the trigraphs would not be well rewarded; however,
mechanical translation of programs without the trigraphs into
those with trigraphs would permit compilation of existing
programs (and those written offline) on a machine without the
characters.

> A general question:  Has the trigraph mechanism been tried out, in real
> practice, anywhere prior to the introduction in X3J11?  If so, I'd like to
> hear about how it's worked out.

I remember all to well writing APL on a machine that had two
kinds of terminals: those with the APL character set and those
without; digraphs were used for entry using the latter.  I also
remember the intense competition to get the terminals with the
APL set.  BUT, we did write an awful lot of code with the
digraphs.