Re: CAP once more

From: [at]} <Bob>
Date: Fri, 17 Sep 2004 19:27:04 +0100

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Hi H.,

> When you look at the output you will remark quite a lot of characters (of
> different gender, i. e. 'letter' and non 'letter') being mapped onto
> themselves whereas others of similar gender are not. So, if despite of
> speed it is possible to do this mapping why isn't it possible in the rest
> of the non sense cases resulting an intuitively understandable and at the
> same time foolproof function?

it is a consequence of the way CAP is defined and implemented in CP,
and of the way Latin-1 is coded.

Latin-1 is arranged in such a way that by ANDing the character with CHR(64)
the result, for letters, is either the capital version of the letter, or the
letter itself (e.g. if the input is 'A' then the output is 'A').

However, it does not work in this way for some non-letter characters; as you
have pointed out, CAP(CHR(247)) = CAP(÷) = ×

There is no sense in which ÷ can be said to have a capital letter, as
far as I know.

Other Oberons do not have a character set as part of the specification of
CAP, and none of them seems to specify the result of executing CAP on a
character like ÷, for which there is no meaningful capital equivalent.
Therefore, if you execute CAP with a non-letter character, all bets
are off. This is rather unfortunate. It would have been better to
define a result for the non-letter case. It should have returned
either the same character that was input, or it should have returned a
value such as 0X, indicating 'no corresponding capital'.

-- 
Regards,
 Bob
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Received on Fri Sep 17 2004 - 20:27:04 UTC