Pavol Droba <droba@topmail.sk> writes:
On Thu, May 06, 2004 at 04:33:54AM -0500, Aleksey Gurtovoy wrote:
[snip]
I wasn't suggesting to re-define the standard's Sequence concept to mean what we want (although that's not entirely impossible). Rather, I was saying that "Collection" is a bad substitute for the occupied term.
I found collection easy to understand. I don't understand what is wrong with it.
There is nothing wrong with the word per se. It just has a commonly accepted meaning that is in conflict with the definition we are giving to the identically named concept. In particular, like I said earlier, "Collection" commonly implies storage, while the concept in question specifically aims to represent sequences that don't have any. Compare, for instance, http://tinyurl.com/32fmb and http://tinyurl.com/3h23s.
It very well fits into the standard concept hierarchy
Collection < Container < Sequence < Associative container
Looks like a total mess to me. If anything, it should be
Sequence < Collection < Container < Associative Container < View
I don't agree, that sequence is a good candidate for this concept as you're suggestion. Sequence directlu implies that elements are sequentialy organized.
Anything with iterators is sequentially organized.
There are operations that are natural only to sequences like push_front/back() front/back() pop_front()/back.
Those are not sequence operations. Alex Stepanov defined "Sequence" for us long before this library: http://www.sgi.com/tech/stl/Sequence.html and the standard contains this definition: Table 67---Sequence requirements (in addition to container) ______________________________________________________________________________ expression return type pre/post-condition assertion/note ______________________________________________________________________________ ______________________________________________________________________________ X(n, t) post: size() == n. X a(n, t); constructs a sequence with n copies of t. ______________________________________________________________________________ X(i, j) post: size() == distance between i and j. X a(i, j); constructs a sequence equal to the range [i,j). ______________________________________________________________________________ a.insert(p,t) iterator inserts a copy of t before p. ______________________________________________________________________________ a.insert(p,n,t) void inserts n copies of t before p. ______________________________________________________________________________ a.insert(p,i,j) void pre: i,j are not iterators into a. inserts copies of elements in [i,j) before p. ______________________________________________________________________________ a.erase(q) iterator erases the element pointed to by q. ______________________________________________________________________________ a.erase(q1,q2) iterator erases the elements in the range [q1,q2). ______________________________________________________________________________ a.clear() void erase(begin(), end()) post: size() == 0. ______________________________________________________________________________
There is nothing like front() for map, yet it can be enumarated,
Maybe the best name for the concept should be "Enumerable". That designates, the primar goal of this conceps, i.e. to be able to enumerate the elementes of an arbitrary collection/container or what ever you name it.
I'd say "Iterable" if we have to use an "-able" term. 24.1/7 suggests to me that "Range" might be OK: Most of the library's algorithmic templates that operate on data structures have interfaces that use ranges. A range is a pair of iterators that designate the beginning and end of the computation. A range [i, i) is an empty range; in general, a range [i, j) refers to the elements in the data structure starting with the one pointed to by i and up to but not including the one pointed to by j. Range [i, j) is valid if and only if j is reachable from i. The result of the application of functions in the library to invalid ranges is undefined. -- Dave Abrahams Boost Consulting http://www.boost-consulting.com