On Tue, Oct 08, 2002 at 06:07:09PM -0700, Larry Wall wrote:
> I've always wondered what the ! postfix operator means. The mathematicians
> think they know. :-)
The Ruby folks think they know. They're method name conventions.
>From "Programming Ruby"
Methods that act as queries are often named with a trailing '?', such
as instance_of?. Methods that are 'dangerous' or modify the receiver,
might be named with a trailing '!'. For instance, String provides
both a chop and a chop!. The first one returns a modified string;
the second modifies the receiver in place. '?' and '!' are the only
weird characters allowed as method name suffixes.
So...
sorted_array = array.sort # return a sorted array
array.sort! # sort in place
is_sorted = array.sorted? # return true if the array is sorted
Interestingly enough, Ruby also supports the ?: operator as Perl does and
does not require whitespace between the tokens.
$foo=1?42:0; # $foo will have 42 in it.
I believe that ? simply binds tighter to method names than the ?:
operator.
This is fine:
print defined? $foo;
This is a syntax error:
print defined? $foo : 42;
/home/schwern/tmp/foo.rb:1: parse error
print defined? $foo : 42;
^
--
Michael G. Schwern <[EMAIL PROTECTED]> http://www.pobox.com/~schwern/
Perl Quality Assurance <[EMAIL PROTECTED]> Kwalitee Is Job One
Cottleston, Cottleston, Cottleston Pie.
Why does a chicken, I don't know why.
Ask me a riddle and I reply:
"Cottleston, Cottleston, Cottleston Pie."
