my $var = "Hello World \x{263a}\cM\x0A This bit is trimmed";
print "\$var is $qesc_to{$var}{30}\n";
# output: $var is "Hello World \x{263A}\r\n..."
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#!/usr/bin/perl -wl
use strict;
use String::Escape qw(printable qprintable elide);
use YAML qw(Dump);
use Interpolation (
        'elide:$$->$' => sub { elide($_[0],$_[1]) },
        'esc' => \&esc,
        'esc_to:$$->$' => sub { elide(esc($_[0]),$_[1]) },
        'qesc' => sub { '"'.esc(@_).'"' },
        'qesc_to:$$->$' => sub { '"'.elide(esc($_[0]),$_[1]).'"' },
        'uniescape' => \&uniescape,
        'yaml' => sub { "\n".Dump($_[0]) },
    );

my %escaped = map { eval qq{"\\$_"} => "\\$_" } qw(a t e f b); # perlo
+p

# String::Escape::printable doesn't always produce valid perl strings
sub esc {  
    local $_ = shift;
    s/([\$"@])/\\$1/g; # interpolators
    s/([\t\e\f\b\a])/$escaped{$1}/g; # portable escapes
    s/\r/\\r/g, s/\n/\\n/g if("\r\n" eq "\cM\cJ"); # non-portable
    s/([^ [:graph:]])/sprintf '\\x{%02X}', ord $1/ge; # \x{} form for 
+clarity
    $_ = uniescape($_);
    return $_;
}

# From /usr/share/perl/5.8.7/dumpvar.pl
sub uniescape {
    join("",
     map { $_ > 255 ? sprintf("\\x{%04X}", $_) : chr($_) }
         unpack("U*", $_[0]));
}


my $var = "Hello World \x{263a}\cM\x0A This bit is trimmed";
print "\$var is $qesc_to{$var}{30}\n";
# OUTPUT: 
# $var is "Hello World \x{263A}\r\n..."

my $long_str = "Some long, long, long, long string";
my $ugly_str = "Some \f string with\r\n\tnewlines,\b tabs & the like \
+x{263a}\n";

print "long string is $elide{$long_str}{25}";
print "ugly_str is $esc{$ugly_str}";
print "ugly_str is $qesc{$ugly_str}";
print "ugly_str is $esc_to{$ugly_str}{35}";
print "ugly_str is $qesc_to{$ugly_str}{35}";
print "ugly_str is $uniescape{$ugly_str}";

# Bonus recipe:
my $ds = [ 1,undef, { b => 3 }];
print "\$ds is $yaml{$ds}";
# OUTPUT:
# $ds is 
# ---
# - 1
# - ~
# - b: 3
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