Hokkaido.pm #4

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34. use strict;
#
my $add = sub { $_[0] + $_[1] };
#
$add->(3, 4);
# => 7
use strict;
sub add {
$_[0] + $_[1];
}
add(2,4);
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35. use strict;
my $c = 3
my $add = sub { $_[0] + $c};
$add->(4);
# => 7
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36. use strict;
my $c = 3
my $proc = sub { $c++ };
$proc->();
# 3
$proc->();
# 4
$proc->();
# 5
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37. use strict;
sub add {
$_[0] + $_[1];
}
my $func = ¥&add;
$func->(3, 4);
# => 7
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38. use strict;
#
sub generate {
my ($a, $b) = @_;
sub { $a + $b };
}
generate(3, 4)->();
# => 7
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39. use strict;
use feature qw(say);
#
sub generate {
my ($num) = @_;
sub { $num++ };
}
my $fun = generate(2);
say $fun->(); # => 2
say $fun->(); # => 3
my $fun2 = generate(2);
say $fun2->(); # => 2
say $fun2->(); # => 3
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42. use strict;
sub each_line {
my ($file, $proc) = @_;
open my $fh “<$file” or return;
while(my $line = <$fh>) {
$proc->($line);
}
close($fh);
}
each_line(‘aaa.txt’, sub { print $_[0] } );
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43. use strict;
sub each_line (&@) {
my ($proc, $file) = @_;
open my $fh, "<$file" or return;
while(my $line = <$fh>) {
$proc->($line);
}
close($fh);
}
each_line { print $_[0]; } ('lex.pl') ;
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45. use strict;
my $table = {
‘left’ => sub { print ‘left’ },
‘right’ => sub { print ‘right’ },
};
sub dispatch {
my ($mode) = @_;
my $func = $table->{$mode};
$func && $func->();
}
dispatch(‘left’);
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47. use strict;
use Log::Dispatch;
my $logger = Log::Dispatch->new;
sub generate_logger {
my ($ip) = @_;
sub { $logger->info(“$ip : $_[0]“) };
}
$custom_logger = generate_logger
(‘192.168.1.1’);
$custom_logger->(“msssssg”)
# => “192.168.1.1 : msssssssg”
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48. sub patial_add {
my ($a) = @_;
sub { add( $a + $_[0] ) };
}
sub add {
$_[0] + $_[1];
}
my $func = patial_add(2);
$func->(5);
# => 7
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50. use strict;
package Collection;
sub new {
my $class = shift;
bless {data => @_}, $class;
}
sub iter {
my $self = shift;
my $counter = 0;
sub { $self->{data}[$counter++] };
}
package main;
my $iter = Collection->new(1, 2)->iter;
say $iter->(); # => 1
say $iter->(); # => 2
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52. use strict;
use feature qw(say);
# 1 ..
my $infinite_list
= sub { my $c = 1; sub { $c++; } };
# 100
my $num_list = $infinite_list->();
for my $i (0..100) {
say $num_list->();
}
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55. my $var = 12;
sub func {
say $var;
}
sub test {
my $var = 19;
func();
}
test(); # => 12
func(); # => 12
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56. local $var = 12;
sub func {
say $var;
}
sub test {
local $var = 19;
func();
}
test(); # => 19
func(); # => 12
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