Re: Re: How's your Perl?

Though I'm almost certain that's what the OP had in mind, it relies on a bug rather than a documented feaure. For that reason I happen to like this solution to question #5 of the OP's quiz:

sub{my$x=\$x};
[download]

Updated version that creates only one $x:

sub { my $x; $x = \$x; }
[download]

The anonymous sub is created and immediately falls out of existance because it's not passed to a scalar variable. And yet $x never disappears because its reference count is always going to be 1; it refers to itself.

It probably doesn't qualify as a static, and is pretty much useless, but it meets the definition of static that the OP gave.

Dave

"If I had my life to live over again, I'd be a plumber." -- Albert Einstein

Comment on Re: Re: How's your Perl? Select or Download Code

Replies are listed 'Best First'.
Re[3]: How's your Perl? by xmath (Hermit) on Oct 27, 2003 at 06:36 UTC
oops, you're right, my definition of "static" in the clarification was flawed :-) I do mean function-scoped static like in C/C++ ofcourse btw tachyon, your #1 solution isn't: `perl -le 'my @x = ( \$_, \$_ ); $x[0]=42; print $x[1]'`	[reply] [d/l]
Re: Re[3]: How's your Perl? by tachyon (Chancellor) on Oct 27, 2003 at 07:26 UTC
Read your rules. You don't specify HOW the value of `$x[0]` is changed :-) vis Create an array @x such that changing `$x[0]` also sets `$x[1]` to the same value While assignment is one way to change a value.... `@x=(\$_,\$_); $_=10; print "\$x[$_] = ${$x[$_]}\n" for 0..$#x; $_=20; print "\$x[$_] = ${$x[$_]}\n" for 0..$#x; __DATA__ $x[0] = 10 $x[1] = 10 $x[0] = 20 $x[1] = 20` [download] cheers $[ tachyon s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print	[reply] [d/l] [select]
Re: Re: Re[3]: How's your Perl? by Juerd (Abbot) on Oct 27, 2003 at 08:11 UTC
Create an array @x such that changing $x[0] ... `@x=(\$_,\$_); my $initial_value = $x[0]; $_=10; print "\$x[$_] = ${$x[$_]}\n" for 0..$#x; die "But \$x[0] did not change.\n" if $x[0] eq $initial_value; $_=20; print "\$x[$_] = ${$x[$_]}\n" for 0..$#x; die "But \$x[0] did not change.\n" if $x[0] eq $initial_value;` [download] You're really printing the wrong thing. `print "\$x[$_] = ${$x[$_]}\n" for 0..$#x; ^^ ^ LHS is $foo, RHS is $$foo. The output is very misleading. print "\${\$x[$_]} = ${$x[$_]}\n" for 0..$#x; LHS is $$foo and RHS is $$foo. But we're interested in $foo. print "\$x[$_] = $x[$_]\n" for 0..$#x; LHS is $foo and RHS is $foo. Output is correct and shows that the need +ed change did not happen.` [download] You're changing the variable that is refered to by the references in $x[0] and $x[1], but you're not actually changing the value in the container that is named $x[0]. Clearer would be: "so that assigning to $x[0] also changes ...", but as said, we're against sanity. Juerd # { site => 'juerd.nl', plp_site => 'plp.juerd.nl', do_not_use => 'spamtrap' }	[reply] [d/l] [select]
Re: Re: Re: Re[3]: How's your Perl? by tachyon (Chancellor) on Oct 27, 2003 at 08:29 UTC
Re: Re: Re: Re: Re[3]: How's your Perl? by Juerd (Abbot) on Oct 27, 2003 at 08:33 UTC
Re[7]: How's your Perl? by xmath (Hermit) on Oct 27, 2003 at 10:06 UTC
Re: Re: Re: How's your Perl? by Anonymous Monk on Oct 27, 2003 at 04:27 UTC
I do not think your code does what you think it does. You have two different `$x` variables shown in your anonymous subroutine, not a single one referencing itself.	[reply] [d/l]
Re: Re: Re: How's your Perl? by Anonymous Monk on Oct 27, 2003 at 05:38 UTC
A static variable in a subroutine context would be created only once and hold its value between invocations. You've created a circular reference in an uninvokable routine. Even if it weren't optimized away, of which I am uncertain, it bears no resemblance to a static variable.	[reply]
Re: Re: Re: Re: How's your Perl? by davido (Archbishop) on Oct 27, 2003 at 06:26 UTC
You are correct, given the conventional definition of a static variable. But the Original Poster provided us with a test of expert Perl prowess, and went so far as to give us his expert definition of static: "static variable" means a variable with infinite lifetime... My solution meets his spec. In a rediculous way, of course... but then again it's a rediculous quiz. Dave "If I had my life to live over again, I'd be a plumber." -- Albert Einstein	[reply]
Re[5]: How's your Perl? by xmath (Hermit) on Oct 27, 2003 at 10:12 UTC
But the Original Poster provided us with a test of expert Perl prowess, and went so far as to give us his expert definition of static ok ok I messed up; because I've had questions about what a "static variable" is (not all perl programmers are C programmers) so I added a quick clarification and got it wrong.. nobody's perfect no need to get sarcastic here My solution meets his spec. In a rediculous way, of course... but then again it's a rediculous quiz. true on both points :-)	[reply]


good chemistry is complicated, and a little bit messy -LW
	PerlMonks