On 2008-May-27, at 9:40 am, Dave Whipp wrote:
TSa wrote:
method inch
{
yield $inch = $.mm * 25.4;
self.mm = $inch / 25.4;
}
Would you regard that as elegant?
That looks functionally incorrect to my eyes: if the caller resumes
at the time of the "yield" statement, and immediately assigns a new
value to the "mm" attribute, then there is a race between the two
updates to "mm".
It seems overly complex to me, but perhaps I'm missing good reasons
for such an approach. I see lvalue subs mainly as syntactic sugar:
foo(42); # arg using normal syntax
foo <== 42; # arg using feed syntax
foo = 42; # arg using assignment syntax
Feeds are a way of passing values to a function, but work like
assignment when used on a variable; assignment is a way of giving a
value to a variable, so it should work like passing args when used on
a function. Then you can easily do whatever you want with it.
In fact, it could work just like a feed, and pass values to the slurpy
params, but I think assignment is special enough to be worth treating
separately. Maybe something like:
sub foo ($arg1, $arg2, [EMAIL PROTECTED], =$x) {...}
foo(6,9) = 42; # the 42 gets passed to $x
That example uses a leading "=" for the "assigned" param (parallel to
the leading "*" for the slurpy param), but I'm not crazy about it for
various reasons (and =$x refers to iteration in other contexts).
Perhaps it could be identified as "$x is assigned" -- but that doesn't
look quite right to me either. However it's written, it would be
simpler than having to use proxies.
-David
