Re: Is it possible to modify __DATA__ via the DATA file handle or otherwise?

It's definitely possible, I would have shown you Ikegami's approach.

But I have trouble imagining a use case where the benefits of this approach outweigh the drawbacks.

The only thing I could come up with was self reproducing code like a virus. (But then you would alter a copy ...)

Cheers Rolf
_{(addicted to the Perl Programming Language and ☆☆☆☆ :)

Wikisyntax for the Monastery}

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Re^2: Is it possible to modify __DATA__ via the DATA file handle or otherwise? by eyepopslikeamosquito (Archbishop) on Feb 11, 2018 at 20:20 UTC
The only thing I could come up with was self reproducing code like a virus Well, it is used effectively as a comedic device in source filter joke modules - such as Acme::Bleach and Acme::Buffy. The Acme::Bleach source is short and amusing (note the use of `0/$0` below to bleach the source file): package Acme::Bleach; our $VERSION = '1.150'; my $tie = " \t"x8; sub whiten { local $_ = unpack "b", pop; tr/01/ \t/; s/(.{9})/$1\n/g; + $tie.$_ } sub brighten { local $_ = pop; s/^$tie\|[^ \t]//g; tr/ \t/01/; pack "b +", $_ } sub dirty { $_[0] =~ /\S/ } sub dress { $_[0] =~ /^$tie/ } open 0 or print "Can't rebleach '$0'\n" and exit; (my $shirt = join "", <0>) =~ s/(.)^\suse\s+Acme::Bleach\s*;\n//sm; my $coat = $1; my $pressed = '#line ' . ("$coat\n" =~ tr/\n/\n/) . ' ' . (caller)[1] +. "\n"; local $SIG{__WARN__} = \&dirty; do {eval $coat . brighten $shirt; print STDERR $@ if $@; exit} unless dirty $shirt && not dress $shirt; open 0, ">$0" or print "Cannot bleach '$0'\n" and exit; print {0} "${coat}use Acme::Bleach;\n", whiten $pressed.$shirt and exi +t; __END__ [download]	[reply] [d/l] [select]

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Re^2: Is it possible to modify __DATA__ via the DATA file handle or otherwise?
by eyepopslikeamosquito (Archbishop) on Feb 11, 2018 at 20:20 UTC

The only thing I could come up with was self reproducing code like a virus

source filter

Acme::Bleach

Acme::Buffy

The Acme::Bleach source is short and amusing (note the use of 0/$0 below to bleach the source file):

package Acme::Bleach;
our $VERSION = '1.150';
my $tie = " \t"x8;
sub whiten { local $_ = unpack "b*", pop; tr/01/ \t/; s/(.{9})/$1\n/g;
+ $tie.$_ }
sub brighten { local $_ = pop; s/^$tie|[^ \t]//g; tr/ \t/01/; pack "b*
+", $_ }
sub dirty { $_[0] =~ /\S/ }
sub dress { $_[0] =~ /^$tie/ }
open 0 or print "Can't rebleach '$0'\n" and exit;
(my $shirt = join "", <0>) =~ s/(.*)^\s*use\s+Acme::Bleach\s*;\n//sm;
my $coat = $1;
my $pressed = '#line ' . ("$coat\n" =~ tr/\n/\n/) . ' ' . (caller)[1] 
+. "\n";
local $SIG{__WARN__} = \&dirty;
do {eval $coat . brighten $shirt; print STDERR $@ if $@; exit}
    unless dirty $shirt && not dress $shirt;
open 0, ">$0" or print "Cannot bleach '$0'\n" and exit;
print {0} "${coat}use Acme::Bleach;\n", whiten $pressed.$shirt and exi
+t;
__END__
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