> I have retained the title of "Lexical variables made default,"
> because I still feel that that is the primary purpose of this change
First off, I think this is a great idea in principle. However, I don't
think it goes nearly far enough in the implementation. I'd like to
propose something radical.
Consider code like this, which is not uncommon:
use strict;
my $var1 = 'some val';
my $var2 = 'some other val';
sub mysub {
my($arg1, $arg2) = @_;
(my $result = $arg1) =~ s/some/every/g;
return ($result, $arg2);
}
my @stuff = mysub($var1, $var2);
You get the idea. Dang there's a lot of my()'s in there! The only thing
I see this RFC changing is the need for the "use strict" statement.
However, the code is still littered with what I would argue are
"useless" my()'s that serve as workarounds for a fundamental flaw in the
langauge: all variables are global by default.
Before you write me back and claim heresy, let me explain what I mean.
When the usage of Perl was basically only as "shell scripting on
steroids", all global variables worked fine. However, as Perl 5 became
more and more powerful and extensible, and classes and OOP became
mainstays, this no longer worked. So, my() is now used pervasively to
manually impose much needed compartmentalization of code.
I argue we should fundamentally shift this thinking in Perl 6. Let's
truly have "lexical variables made default". Let's change the above code
to:
#use strict; # unneeded, now implied
$var1 = 'some val'; # my() now default
$var2 = 'some other val';
sub mysub {
($arg1, $arg2) = @_;
($result = $arg1) =~ s/some/every/g;
return ($result, $arg2);
}
@stuff = mysub($var1, $var2);
One basic rule of user interface is that "if something's easy and
repetitive, have the computer do it". I would argue my() is such a
beast. I propose these changes:
1. "use strict" as default
2. my() the default scope of vars
If Perl 6 is going to be successful and hailed (as I'm sure we all hope
it is), I think it has to offer some clear advantages that make things
easier. Consider which of these sounds more like a benefit:
1. setting "use strict" on by default, forcing
users to formally declare all their variables
as my()'s
2. making it so that they don't have to anymore
I would argue that (1) is a burden, but (2) is a benefit. Doing it this
way doesn't break scripts either - in fact it makes it easier to avoid
accidental errors, even in "quick-and-dirty" scripting:
sub square {
($x) = @_;
$x *= $x;
}
$x = 2;
$ans = square($x);
print "$x squared is: $ans\n"; # uh-oh
One could argue that "you shouldn't make this mistake", but c'mon. We're
human, and I'm sure everyone on this list has done this. Let's make Perl
6 do the hard work for us. :-) Moreover, we can leave my() just as-is,
so if someone wants to explicitly use it for clarity they're welcome to.
-Nate
P.S. I know that square() example is trite, but it's the best I could do
in 30 seconds. :-)
