Re: Pointers In C++
* Stefan Ram:
James Kanze <james.kanze@gmail.com> writes:
IIRC, both ?pointer? and ?variable? are not defined explicitly
of this International Standard are defined where they are used
and italicized where they are defined." Of course, I'm not
Thanks for the hint regarding italis! It helps to know when
ISO/IEC 14882:2003(E) deems a term to be ?defined?.
Both of you, James and Alf, refer to ?definition?, while I
was using ?explicit definition?.
To me, an ?explicit definition? is a definition of the
following form:
?An <new term> is a <known superordinate concept>,
so that <complete list of requirements> are fulfilled.?
For example, for ?object?,
?An object is a region of storage that has a type.?
Not in C++.
Or (in mathematics), for ?x?,
?x e N, 0 = x + 2.?
(x is a natural number, so that x plus 2 is zero.)
Hm, no such. :-) Except in the context of modulo arithmetic. But if you write
'-' instead of '+' then you have an implicit definition, not an explicit one,
because the definition can't be substituted for an occurrence of x; the
definition is not of the form "x is ...".
On the other hand, just stating one property, but not all
properties required, and not giving a known superordinate
concept is not an explicit definition to me. For example,
the following is not an explicit definition of ?car?:
A car can be obtained by a visit to a car shop.
It seems that the argument is that some definitions do not impose enough
constraints to your taste, here that you have a much more constraining
definition in mind, and would like the quoted definition to also impose those
constraints. First, that has nothing to do with explicit versus implicit.
Secondly, where the standard does not impose a given constraint, it's often for
some good reason (e.g., there's no formal requirement that a "region of storage"
is contiguous, and AFAIK this was for good committee-political reason, not the
ungood technical one of supporting virtual inheritance).
Cheers, & hth.,
- Alf
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