On 11/5/23 01:36, Waldek Hebisch wrote:
_Any_ attempt to read elements of uninitialized array may lead to troubles. So it is not only printing, but in general it is unsafe to pass uninitialized array to a routine, unless one _knows_ that the routine will initialize the array.
Yes, exactly that is the point. qnew claims to return an object of type %, but, in fact, it doesn't.
We could add the followowing to description of 'qnew': Use only when you know what you are doing.
That is one thing, but does not give enough information. How should a user know what he is doing? Where would he get this information from?
A better phrase would perhaps be: qnew constructs structure with uninitialized elements. Do not pass such a structure to other functions before its parts are initialized via setelt! or qsetelt!.
Possibly we could add a FAQ entry with some explanation.
Additionally also good, but I doubt that people jump to the FAQs if the stumple over problems with qnew.
I have doubts about general usefulness of NonNegativeInteger.
Indeed. There is no subtraction. Yes, that's not a total function in NNI, but in most use cases the programmer knows that the result is still in NNI. I sometimes wished there where a "minus: (NNI, NNI) -> NNI" that throws an error if the result becomes negative. But I do not care too much.
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