On Nov 23, 2011, at 13:27, David Herman wrote: > An additional point about consistency: many scripting languages talk about > the "length" of a table data structure because they actually expose the > representation of a table as an array or list.
I dispute your examples, as follows: > IIRC Perl/PHP associative arrays, In Perl, _hashes_ are different builtin objects from _arrays_; they merely have useful conversion behavior when used in _list context_ (which is a call-semantics issue unrelated to data structures). The way to get the number of elements is to call 'keys %myhash' in scalar context. 'length %myhash' will do something useless. I'm not familiar with PHP. > Python dicts, Again, different builtin objects. If they have any array nature, it is not exposed to the programmer; myDict[key] gets you a lookup by hash key, not array indexing. > Lisp alists, An alist in Lisp is not a distinctly typed data structure at all; it is only and entirely a particular application of linked lists (which are an application of cons cells (pairs/tuples)) for which there are utility functions in the standard library. A (Common) Lisp programmer looking for the size of an alist would indeed (length my-alist), but if they had a hash table it would be (hash-table-count my-ht). (In CL, the length function applies to all _sequences_, but a hash table is not a sequence; there are no functions generic over all kinds of collections.) > and Ruby hashes are all transparently built from arrays or lists. But Map and > Set aren't arrays, they're their own data structure. So IMO it makes sense to > name their methods on their on terms, not on the terms of a different data > structure. (For what it's worth, I agree with the previous suggestion to make .length used only for things which have [0], [1], [2], …; and that if it is instead a collection with .get() and .put()/.set() or similar then .size() or .count() makes sense.) -- Kevin Reid <http://switchb.org/kpreid/> _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
