perl と対比させてく。

基本1

perl

package Foo;
sub new  { bless { a => pop }, shift }
sub echo { print shift->{a}, "\n" }
1;

Foo->new("foo")->echo ;

python

class Foo(object):
    def __init__(self,a):
        self.a = a
    def echo(self):
        print(self.a)

Foo("foo").echo()

基本2

perl

package Foo;
sub new { bless {}, shift }
sub add { ++ shift->{c} }
1;

my $c = Foo->new ;
print $c->add . "\n" for 0 .. 9 ;

python

class Foo(object):
    def __init__(self):
        self.a = 0
    def add(self):
        self.a = self.a + 1
        return self.a

o = Foo()
for i in range(10):
    print (o.add())

引数をハッシュ(辞書)で

perl

package Foo;
sub new   { bless { c => 10, @_[1..$#_]}, shift }
1;

use Data::Dumper ;
my $obj = Foo->new( d => 10) ;
print Dumper $obj ;

python

class Foo(object):
    def __init__(self, **args):
        self.__dict__ = { 'c':10 }
        self.__dict__.update( args )

o = Foo(d=10)
print (vars(o))

シングルトン

perl

package Foo;

my $s ;
sub new { $s ||= bless {}, shift ; }
sub add { ++ shift->{c} }

1;

my $o = Foo->new ;
my $p = Foo->new ;
print  $o . "\n";
print  $p . "\n";
print $o->add . "\n";
print $p->add . "\n";

python

class Foo(object):
    _instance = None
    def  __new__(cls):
        if cls._instance is None:
            cls._instance = object.__new__(cls)
        return cls._instance
    def __init__(self):
        self._x = 0
    def add(self):
        self._x = self._x + 1
        return self._x

o = Foo()
p = Foo()
print (id(o))
print (id(p))
print (o.add())
print (p.add())

コールバック

もちょっと真面な例に差し替え予定

perl

package Foo;
sub new     { bless pop, shift ; } ;
sub execute { shift->(pop); }
1;

my $obj = Foo->new( sub { print $_[0] ; } ) ;
$obj->execute( 'foo' ) ;

python

# from __future__ import print_function
class Foo(object):
    def __init__(self, f):
        self._f = f
    def execute(self):
        self._f()

o = Foo(lambda : print ('foo'))
o.execute()

2系で使いたければコメントをアンコメント