[python] Pulnocni rozjimani :-)

[Hynek Fabian]

Skutecna zlodejna neni tak hezky deklarovana,
ale dela se pekne pod rukou:

a = SuperMaxiSecureAccount()
a.__class__ = Thief

On 05/12/2015 12:46 AM, Jan Bednařík wrote:
> Trošku z jiného soudku:
> 
> $ python3
> Python 3.4.3 (default, Mar 23 2015, 04:19:36)
> [GCC 4.2.1 Compatible Apple LLVM 6.0 (clang-600.0.57)] on darwin
> Type "help", "copyright", "credits" or "license" for more information.
>>>>
>>>> class Account:
> ...     def deposit(self, amount):
> ...         print('saved:', amount)
> ...
>>>> class SecureAccount(Account):
> ...     def safe_deposit(self, amount):
> ...         print('*secure transaction begin*')
> ...         super().deposit(amount)
> ...         print('*secure transaction end*')
> ...
>>>> sa = SecureAccount()
>>>> sa.safe_deposit(100)
> *secure transaction begin*
> saved: 100
> *secure transaction end*
>>>>
>>>> class Thief(Account):
> ...     def deposit(self, amount):
> ...         print('STOLEN:', amount)
> ...
>>>> class MyAccount(SecureAccount, Thief):
> ...     pass
> ...
>>>> ma = MyAccount()
>>>> ma.safe_deposit(200)
> *secure transaction begin*
> STOLEN: 200
> *secure transaction end*
>>>>
> 
> Honza
> 
> 2015-05-11 23:57 GMT+02:00 Matěj Cepl <mcepl na cepl.eu
> <mailto:mcepl na cepl.eu>>:
> 
>     On 2015-05-11, 20:53 GMT, Honza Král wrote:
>     > Jen pozor, ze tohle je chovani CPythonu, tedy jedne z implementaci a
>     > nikoli definice chovani pythonu, nelze tedy na to spolehat a
>     > porovnavani integereru by se melo vzdy provadet pres == a nikdy pres
>     > is, i kdybychom meli 1000% jistotu, ze to budou jen cisla od 0 do 10.
>     > Honza Král
> 
>     Skutečně, neni Python jako Python:
> 
>         $ jython
>         Jython 2.7b4 (default:3672e624962a, Feb 13 2015, 04:59:14)
>         [OpenJDK 64-Bit Server VM (Oracle Corporation)] on java1.7.0_79
>         Type "help", "copyright", "credits" or "license" for more
>     information.
>         >>> a = 256
>         >>> b = 256
>         >>> a is b
>         True
>         >>> a = 257
>         >>> b = 257
>         >>> a is b
>         True
>         >>>
>         $
> 
>     Zajímavě,
> 
>     Matěj
>     --
>     http://www.ceplovi.cz/matej/, Jabber: mcepl<at>ceplovi.cz
>     <http://ceplovi.cz>
>     GPG Finger: 89EF 4BC6 288A BF43 1BAB  25C3 E09F EF25 D964 84AC
> 
>     The ratio of literacy to illiteracy is a constant, but nowadays
>     the illiterates can read.
>         -- Alberto Moravia
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> 
> 
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