>It doesn't help that Camel II's glossary defines "array" as "A named list
>of values, each of which has a unique key to identify it. In a normal
>array, the key is numeric... In a hash...the key is a string." and seems to
>go to a lot of effort to deprecate "array" in favor of "list" (array
>context: "A quaint, archaic expression used by people who have read the
>first edition of this book. Nowadays called 'list context'.").
Here's from Camel III. I hope you find this more helpful than before.
=item B<array>
An ordered sequence of values, stored such that you can easily access
any of the values using an integer subscript that specifies the value's
offset in the sequence.
=item B<array context>
An archaic expression for what is more correctly referred to as I<list
context>
=item B<hash>
An unordered association of I<key>/I<value> pairs, stored such
that you can easily use a string I<key> to look up its associated
data <value>. This glossary is like a hash, where the word to be
defined is the key, and the definition is the value. A hash is
also sometimes septisyllabically called an "associative array",
which is a pretty good reason for simply calling it a "hash" instead.
=item B<hash table>
A data structure used internally by Perl for implementing associative
arrays (hashes) efficiently. See also I<bucket>.
=item B<LIST>
A syntactic construct representing a comma-separated list of
expressions, evaluated to produce a I<list value>. Each I<expression>
in a R<LIST> is evaluated in a I<list context> and interpolated into
the list value.
=item B<list>
An ordered set of scalar values,
=item B<list context>
The situation in which an I<expression> is expected by its surroundings
(the code calling it) to return a list of values rather than a
single value. Functions that want a R<LIST> of arguments tell those
arguments that they should produce a list value. See also I<context>.
>Reading that, what would you say the difference between an array, a list,
>and a hash is?
I'm not sure from reading that. The answer that comes to my mind
is that an array has an AV (updatable array metadata header
structure) and a hash an HV (similarly), but a list--well, that's
just SVs sitting around on a stack somewher. But that's not very
useful for anyone who's still confused.
>(My answer: From that glossary, I'd say that 'array' and 'list' are
>virtually synonymous. From actual use, I'd say that an array can be an
>lvalue, but a list is strictly an rvalue.)
Actually, you *can* use a list lvalueably, provided that each of that
list's components is also a legal lvalue. For example:
($a, $b, $c, $d, @etc) = fn();
However, currently you can't switch those, even for lvaluable functions.
--tom
