8-Bit characters for Ada

8-Bit characters for Ada

[David B. Kinder]

AI-420 (submitted over 3 years ago) brought up the issue of an an 8-bit 
character type.  This should be a hot issue with non-US Ada customers who 
should reasonably insist on support for their (non-English) characters in 
STRING variables and in TEXT_IO.  I've seen packages that define a new 
extended character type, however this character type can't be used with 
TEXT_IO, so a whole new (and non-standard) I/O package must be used.  

Are there Ada users concerned with this problem?  Have there been any 
further thoughts by the LMC/ARG on supporting 8-bit characters?  Can we get 
some definitive ruling on AI-420?  What do you Ada developers think about 
direct language support for 8-bit characters?  

-- David Kinder, BiiN

Re: 8-Bit characters for Ada

[Erland Sommarskog]

David Kinder (kinder@biin.com) writes:
>AI-420 (submitted over 3 years ago) brought up the issue of an an 8-bit 
>character type.  This should be a hot issue with non-US Ada customers who 
>should reasonably insist on support for their (non-English) characters in 
>STRING variables and in TEXT_IO.  I've seen packages that define a new 
>extended character type, however this character type can't be used with 
>TEXT_IO, so a whole new (and non-standard) I/O package must be used.  

I recall I brought up this problem in this newsgroup a little more than a 
year ago. The conclusion if you wanted to use eight-bit characters was
to define a new type with a new Text_IO or to simply cheat. (You are
not really required to write an entirely new Text_IO you can map to 
the old, but you still have problems with being non-standard.) The big
problem with Ada is that it defines only characters 32-126 as printable.
It also says that a user that in/outputs non-prinable charcaters cannot
rely on that Text_IO works as described.
  I generally very hesitant to proposals to change the Ada standard. One
point with Ada was that it should be complete. But a minor change like
extending Ada to support the ISO/Latin standards (8859/1-9) has my full 
support. I even see it as necessary. At minimum 8859/1 should be supported.

I don't know about AI-420. Could you, or anyone else, give more info?
-- 
Erland Sommarskog
ENEA Data, Stockholm
sommar@enea.se
"Frequently, unexpected errors are entirely unpredictable" - Digital Equipment