Perl中級者への道 (近藤嘉雪, at PerlCasual #4)

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Perl
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@yoshiyuki kondo

PerlCasual #4 (2011/4/28)

(@yoshiyuki kondo) Perl PerlCasual #4 (2011/4/28) 1 / 44

( )


( )
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@yoshiyuki_kondo

http://www.kondoyoshiyuki.com/


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@yoshiyuki_kondo


Perl
Perl


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@yoshiyuki_kondo


Perl
Perl

C
Java


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@yoshiyuki_kondo


Perl
Perl

C
Java

:


( )
Twitter
@yoshiyuki_kondo


Perl
Perl

C
Java

:
:


( )
Twitter
@yoshiyuki_kondo


Perl
Perl

C
Java

:
: Emacs


( )
Twitter
@yoshiyuki_kondo


Perl
Perl

C
Java

:
: Emacs
:


( )
Twitter
@yoshiyuki_kondo


Perl
Perl

C
Java

:
: Emacs
: T-Code (2 )


Perl


Perl

Perl


use strict
use warnings


use strict
use warnings

#!/usr/bin/perl

use strict;
use warnings;


use strict


use strict
use strict

OK


use strict
use strict

OK
#!/usr/bin/perl
use strict;
use warnings;

$foo = 10; # $foo
my $bar = 2;
print $foo, "n"; # $foo
print $bar, "n";
print $x, "n"; # $x


use strict
use strict

OK
#!/usr/bin/perl
use strict;
use warnings;

$foo = 10; # $foo
my $bar = 2;
print $foo, "n"; # $foo
print $bar, "n";
print $x, "n"; # $x

Global symbol "$foo" requires explicit package name at ....


warnings


warnings
use warnings


warnings
use warnings

#!/usr/bin/perl
use strict;
use warnings;

my $foo = "10xxx";
my $x = $foo + 5; # $foo
my $bar;
print "$barn"; # $bar undef


warnings
use warnings

#!/usr/bin/perl
use strict;
use warnings;

my $foo = "10xxx";
my $x = $foo + 5; # $foo
my $bar;
print "$barn"; # $bar undef

Argument "10xxx" isn’t numeric in addition (+) at ....
Use of uninitialized value $bar in concatenation (.) or string at ....


#!/usr/bin/perl

use strict;
use warnings;


#!/usr/bin/perl

use strict;
use warnings;

!!

open

open


open

Perl
open INPUT, "<mydata" or die "Cannot open ’mydata’: $!n";
while (<INPUT>) {
print $_;
}
close INPUT;


open

Perl
while (<INPUT>) {
print $_;
}
close INPUT;

open my $input, "<", "mydata" or die "Cannot open ’mydata’: $!n";
while (<$input>) {
print $_;
}
close $input;


open

Perl
while (<INPUT>) {
print $_;
}
close INPUT;

open my $input, "<", "mydata" or die "Cannot open ’mydata’: $!n";
while (<$input>) {
print $_;
}
close $input;

$input


open

3 open
open my $input, "<", "mydata"


open

3 open
1

1 my


open

3 open
1

1 my

2


open

3 open
1

1 my

2
3


open

open 1


open

open 1

while (<$input>) { ......
my $line = <$input>;


open

open 1


print {$output} "This is a linen"; #
print $output "This is a linen"; #


open

open 1


print $output, "This is a linen"; #


open

open 1


print $output, "This is a linen"; #

IO::File
$output->print("This is a line datan");


reference


reference

C


reference

C

etc.


C
$scaler_ref = $scalar; #


C
$array_ref = @array; #


C
$hash_ref = %hash; #


C
$func_ref = &function; #


C
$func_ref = &function; #
$glob_ref = *STDOUT; #


dereference


dereference

Perl


$sref = $x;


$sref = $x;

$a = $$ref;


$sref = $x;

$a = $$ref;

my $x = 100;
my $sref = $x; # $sref

print "$$sref $xn"; # 100 100
$$sref += 5;
print "$$sref $xn"; # 105 105

$array_ref = @array;



@s = @$array_ref;



@s = @$array_ref;

$$array_ref[10] = 10;



@s = @$array_ref;

$$array_ref[10] = 10;
foreach
foreach (@$array_ref) {


compute sum:

sub compute_sum {
my ($aref) = @_; # $aref
my $sum = 0;
foreach (@$aref) { #
$sum += $_;
}
return $sum;
}


$href = %h;


$href = %h;

$x = $$href{’a’};


$href = %h;

$x = $$href{’a’};
keys
foreach (keys %$href) {


(coderef)


(coderef)

$fref = &func;


(coderef)

$fref = &func;

&$fref($param);


$aref = @array;
$$aref = 10;
Not a SCALAR reference at - line 7.


ref

REF
SCALAR
ARRAY
HASH
CODE
GLOB


print


print
16
CODE(0xbb5b48), HASH(0xbb59f8)


print
16
CODE(0xbb5b48), HASH(0xbb59f8)
eq


${$sref}


${$sref}

@{&get_array_ref()}


${$sref}

@{&get_array_ref()}
${$a[2]} $$a[2]
$$a[2] ${$a}[2]


${$a[2]} $$a[2]


->
$a->[3] $$a[3]


->
$a->[3] $$a[3]
$h->{key} $$h{key}


->
$a->[3] $$a[3]
$h->{key} $$h{key}
$f->($param) &$f($param)


->
$a->[3] $$a[3]
$h->{key} $$h{key}

$a->[3]->[2]


->
$a->[3] $$a[3]
$h->{key} $$h{key}

$a->[3]->[2]
-> [],{} () ->
$a->[3]->[2] $a->[2][3]


$a[3][2][5]


$a[3][2][5]

$a[3]->[2]->[5]


$a[3][2][5]

$a[3]->[2]->[5]
$a->[3][2][5]


$a[2][1] $a->[2][1]


Perl


Perl

$a[2][3]


Perl

$a[2][3]

$a[2][1] = 100


compute sum
my @tmp_array = (1, 3, 5, 7, 9);
print "Total: ", compute_sum(@tmp_array), "n";

sub compute_sum {
my ($aref) = @_;
my $sum = 0;
foreach (@$aref) {
$sum += $_;
}
return $sum;
}


compute sum
my @tmp_array = (1, 3, 5, 7, 9);
print "Total: ", compute_sum(@tmp_array), "n";

sub compute_sum {
my ($aref) = @_;
my $sum = 0;
foreach (@$aref) {
$sum += $_;
}
return $sum;
}
@tmp array


Perl (anonymous array)

[]


Perl (anonymous array)

[]

)
5 $aref

$aref = [1, 2, 3, 4, 5]


compute sum
print "Total: ", compute_sum([1, 3, 5, 7, 9]), "n";


compute sum
print "Total: ", compute_sum([1, 3, 5, 7, 9]), "n";
(1, 2, 3) [1, 2, 3]


anonymous
hash
{}


anonymous
hash
{}

) 3

$href = {one => 1, two => 2, three => 3};


=>
=> (thick arrow) (
Perl p121)


=>
=> (thick arrow) (
Perl p121)

=> (
)


=>
=> (thick arrow) (
Perl p121)

=> (
)


$href = {’one’, 1, ’two’, 2, ’three’, 3 };


=>
=> (thick arrow) (
Perl p121)

=> (
)



=>


=>
=> (thick arrow) (
Perl p121)

=> (
)



=>
( )

( )

my $userinfo = { name => $name,
uid => $uid,
gid => [1, 200, 201, 203],
env => {
HOME => $ENV{HOME},
TERM => "VT100" } };


Data::Dumper

?


Data::Dumper

?
HASH(0x116360)


Data::Dumper

?
HASH(0x116360)
Data::Dumper
$VAR1 = {
’uid’ => 1001,
’env’ => {
’HOME’ => ’/home/cond’,
’TERM’ => ’VT100’
},
’name’ => ’John’,
’gid’ => [
1,
200,
201,
203
]
};


( )

( )


( )

Perl anonymous
subroutine


( )

Perl anonymous
subroutine
sub { ..... }


( )

Perl anonymous
subroutine
sub { ..... }

fref
$fref = sub { print "Hello, $_[0]n"; }


( )

Perl anonymous
subroutine
sub { ..... }

fref

&$fref("world");


( )

Perl anonymous
subroutine
sub { ..... }

fref

&$fref("world");
-> (
)
$fref->("world");


( )

(closure) ?

(my )


( )

adder:

sub adder {
my ($increment) = @_; #

return sub {
my ($x) = @_;
return $x + $increment;
}
}

my $add1 = adder(1); # 1
my $add20 = adder(20); # 20

print $add1->(10), "n"; # 11
print $add20->(10), "n"; # 30
print $add1->(30), "n"; # 31

( )

make counter:

sub make_counter {
my ($counter) = @_; #

return sub { return ++$counter };
}

my $foo = make_counter(0); # 0
my $bar = make_counter(100); # 100

print $foo->(), "n"; # 1
print $bar->(), "n"; # 101
print $bar->(), "n"; # 102
print $foo->(), "n"; # 2
print $bar->(), "n"; # 103
print $foo->(), "n"; # 3


( )


( )

use strict
use warnings


Perl中級者への道 (近藤嘉雪, at PerlCasual #4)

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