Re: Metaprogramming
Steffen Mueller:
So any code that uses closures is pathological?
Hmm, let's see:
perl -MO=Deparse -e 'my $x; {my $foo = Hello!; $x=sub{print $foo};}; $x-()'
my $x;
{
my $foo = 'Hello!';
$x = sub {
print $foo;
}
;
}
$x();
Nope, seems not.
--
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Citizen_X maybe they're afraid someone might steal the car in the short time
before they turn off the alarm and actually get in
Citizen_X it's a race condition, you know
Re: Metaprogramming
Simon Cozens wrote:
Steffen Mueller:
I've been wondering whether it is possible to implement some kind of
mechanism that allows a Perl script to modify itself at runtime.
B::Generate's been doing this for ages.
Okay, I read up on it, but:
You are expected to have read the Perl and XS sources to this module
before attempting to do anything with it.
I cannot read XS :)
Well, eventually, I might teach myself to, but I doubt that will be just
to implement foolish things as described in the other post.
Thanks for the pointer anyway.
Steffen
--
sub'_{q} tsuJ}}_();sub's{seek+DATA,0,0}sub'p{print_}sub'r{reverse$_[0]}
@_=(('')x2,split ,DATA);s!!s,$_=DATA;s/}.*?}/$_[$s+1]/
if$s;s/(}.*?})/r$1/e;eval$_;p,$s++!efor@_[0..3];
__DATA__
} rehtona} } lreP} },rekcah}
Re: Metaprogramming
Steffen Mueller: Okay, I read up on it, but: You are expected to have read the Perl and XS sources to this module before attempting to do anything with it. I cannot read XS :) Yeah, it was just a long-term plot to sell more books. -- IBM: It may be slow, but it's hard to use.
Re: Metaprogramming
Michael == Michael G Schwern [EMAIL PROTECTED] writes: Nope, I've given examples of subroutines that cannot currently be accurately deparsed. Michael Because of the nature of Perl or because of a mistake in B::Deparse? Not completely sure. The problem is closures, because you end up having to figure out how to construct the right sharing of lexicals amongst the various coderefs you've discovered. -- Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095 [EMAIL PROTECTED] URL:http://www.stonehenge.com/merlyn/ Perl/Unix/security consulting, Technical writing, Comedy, etc. etc. See PerlTraining.Stonehenge.com for onsite and open-enrollment Perl training!
Re: fun with regex
On Dec 12, Abigail said:
On Thu, Dec 12, 2002 at 12:48:11AM -0500, Jeff 'japhy' Pinyan wrote:
On Dec 12, Jonathan E. Paton said:
(my $sql = '--') =~ s/\A(\s+)(?{$::c = $^N})|^(??{$::c})//gm;
all over SQL related source code then your head is on the block!
While it's cool, and I'D use it, for readability purposes, might I
suggest:
$sql =~ /(\s*)/ and $sql =~ s/^$1//mg;
The question was how to do it in one regex; the original poster
already knew how to do it with two regexes.
Yes, that's all well and good. Your one-regex solution is the way I would
do it (with one regex too), but if you're going to use two regexes, I'd
use my method.
--
Jeff japhy Pinyan [EMAIL PROTECTED] http://www.pobox.com/~japhy/
RPI Acacia brother #734 http://www.perlmonks.org/ http://www.cpan.org/
stu what does y/// stand for? tenderpuss why, yansliterate of course.
[ I'm looking for programming work. If you like my work, let me know. ]
grep substitute
FWPers, Pretending your machine did not have e?grep, how concisely could you duplicate the GNUish -q (silent) functionality: stop scanning on first match and exit(0). If no match, exit(1). Here's something simple to start with: perl -n0777 exit !(/pattern/) Necessary Improvements: - concisely get the pattern from the command-line (e.g., pattern as $ARGV[0] and the file as $ARGV[1]) such that the syntax is more like grep (e.g., grep 'pattern' filename = perl -args 'pattern' filename)? Extra Credit: - is there a short way to do it without slurping the whole file? Any takers? Scott -- Scott Wiersdorf [EMAIL PROTECTED]
Re: grep substitute
On Fri, Dec 13, 2002 at 05:31:35PM -0700, Scott Wiersdorf wrote:
FWPers,
Pretending your machine did not have e?grep, how concisely could you
duplicate the GNUish -q (silent) functionality: stop scanning on
first match and exit(0). If no match, exit(1).
Extra Credit:
- is there a short way to do it without slurping the whole file?
perl -n
/pattern/ exit 1; END { exit !$? }
Scott
--
Scott Wiersdorf
[EMAIL PROTECTED]
Re: Metaprogramming
Steffen == Steffen Mueller [EMAIL PROTECTED] writes:
Steffen Okay, I admit to have relied on an overgeneralized interpretation of
Steffen Randal's post about closures being a problem for B::Deparse.
Steffen I *do*, however, remember B::Deparse failing to deparse some entries
Steffen to the tpr04b golf contest which posed some trouble to my judging the
Steffen entries. Those pieces of code qualify as pathological, I suppose. :)
Let's see if this is the one:
sub black_adder {
my $constant = shift;
sub { $constant + shift; }
}
my $to_deparse = black_adder(42);
use B::Deparse;
print \n, B::Deparse-new-coderef2text($to_deparse), \n;
==
{
$constant + shift(@_);
}
Ayup. That's the one. *What* constant? :) And that was the
first odd one I tried. I could probably construct weirder ones
once that one is fixed.
So, coderefs that have been closed, break.
--
Randal L. Schwartz - Stonehenge Consulting Services, Inc. - +1 503 777 0095
[EMAIL PROTECTED] URL:http://www.stonehenge.com/merlyn/
Perl/Unix/security consulting, Technical writing, Comedy, etc. etc.
See PerlTraining.Stonehenge.com for onsite and open-enrollment Perl training!
