[BLACKBOX] Conversion & Casting

From: [at]} <Robert>
Date: Mon, 25 Oct 2010 22:10:52 +0100

----boundary-LibPST-iamunique-1267362632_-_-
Content-type: text/plain

On 21/10/2010 23:32, Chris Burrows wrote:

> If what you actually need is type *conversion* (for types of different size)
> rather than type *casting* then you should use the built-in procedures LONG
> and SHORT to convert from one type to another.


Folks, I am rather confused by recent posts because I don't really understand
the jargon.


Does (*conversion*) mean using different bit patterns too represent the same 'idea'?
For example the idea "-3" might be represented as C008 0000 0000 0000 as a REAL,
as FFFF FFFF FFFF FFFD as a LONGINT, as FFFF FFFD as an INTEGER, and so on. Such
transformations would use SHORT, LONG, ENTIER and implicit conversions.


Does (*casting*) mean using the same bit pattern to represent different ideas?
For example FFFF FFFD would represent -3 as an INTEGER and {0, 2..31} as a SET.
Such transformations would ideally use functions such as BITS & ORD, but would
need SYSTEM.VAL when the CP language did not give explicit support (eg from
POINTER to INTEGER)?


What (*should*) SYSTEM.VAL do when the input and output have differing numbers
of bits (which seems to be the case in recent discussions)?


What (*does*) SYSTEM.VAL do when the input and output have differing numbers of
bits?


Cheers

Robert

----
To unsubscribe, send a message with body "SIGNOFF BLACKBOX" to LISTSERV{([at]})nowhere.xy----boundary-LibPST-iamunique-1267362632_-_-
Content-type: application/rtf
Content-transfer-encoding: base64
Content-Disposition: attachment; filename="rtf-body.rtf"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----boundary-LibPST-iamunique-1267362632_-_---

Received on Mon Oct 25 2010 - 23:10:52 UTC