Re: Efficient Sequential Access to Arrays

[Shark8 <onewingedshark@gmail.com>]

>>> These assumptions must be upheld per value construction.
>>
>> Er, yes? Your value-construction procedure, which might be a
>> stream-implementation, could use 'Input to ensure the data is valid, no?
>> Then isn't the 'Read the value-construction?
>
>Neither. If you use stream you should do it properly, i.e. as the transport
>layer. The transport is defined in terms of bytes, characters or other
>units. So the only read here might be Character'Read.

Um, I think you completely misread what I was saying. You can use 'Read and 'Write to handle your import/export to the requisite format; the 'Write shouldn't be an issue (WRT validity; at this point your object should be valid and your writing it out should be straightforward), but the 'Read certainly needs to check for validity. Using Character'Read is perfectly reasonable when talking about parsing from text into the internal types, as I was doing in my LISP interpreter; indeed I was using Character'Read.

'Valid might be a perfectly reasonable way to raise an exception; as I said before many DBs do not have ranges on their values; if your data (say for a simulation) is exported to a DB, then any import needs to check that the constraints on the fields [present in the program, not present in the DB] have not been broken. (A common cause would be because of some SQL update-statement some user ran.) Why would using 'Valid be the wrong way to go if those constraints were strictly subranges?