iisaka51

Python@Osakaについて

PythonのコミュニティーとしてPython大阪の会に携わっていまして、 Scapbox でも PythonOsaka に資料を多数アップしていています。

Python@Osaka としたのはアットマーク( @ )が蛇がとぐろを巻いていようにも見えることと、 大阪でのコミュニテイーを表すのにちょうどよいと思ったしだいです。

iisaka51

try:
    # python 3.8 or later
    from functools import singledispatchmethod
except ImportError:
    from functools import singledispatch, update_wrapper

    def singledispatchmethod(func):
        dispatcher = singledispatch(func)
        def wrapper(*args, **kw):
            return dispatcher.dispatch(args[1].__class__)(*args, **kw)

iisaka51

In [1]: from datajuggler import serializer as io

In [2]: io.read_contents('sqlite:///users.sqlite#users')
Out[2]:
[{'id': 1, 'name': 'David Coverdale', 'age': 71, 'belongs': 'Whitesnake'},
 {'id': 2, 'name': 'Neal Schon ', 'age': 68, 'belongs': 'Journey'},
 {'id': 3, 'name': 'Tom Scholz', 'age': 75, 'belongs': 'Boston'},
 {'id': 4, 'name': 'David Gilmour', 'age': 75, 'belongs': 'Pink Floyd'},
 {'id': 5, 'name': 'Ann Wilson', 'age': 71, 'belongs': 'Heart'},
 {'id': 6, 'name': 'Nacy Wilson', 'age': 67, 'belongs': 'Heart'}]

iisaka51

In [8]: # %load users_class.py
   ...: class User:
   ...:
   ...:     def __init__(self, *nargs, **kwargs):
   ...:         self.data = dict(*nargs, **kwargs)
   ...:         self.id: int = self.data['id']
   ...:         self.name: str = self.data['name']
   ...:         self.age: int = self.data['age']
   ...:         self.belongs: str = self.data['belongs']
   ...:

iisaka51

In [4]:  class User:
   ...:
   ...:     def __init__(self, *nargs, **kwargs):
   ...:         self.data = dict(*nargs, **kwargs)
   ...:         self.id: int = self.data['id']
   ...:         self.name: str = self.data['name']
   ...:         self.age: int = self.data['age']
   ...:         self.belongs: str = self.data['belongs']
   ...:

iisaka51

In [18]: from typing import NamedTuple
    ...:
    ...: try:
    ...:     class User(NamedTuple):
    ...:         id: int
    ...:         name: str
    ...:         age: int
    ...:         belongs: str
    ...:
    ...:         def __init__(self, profile):

iisaka51

In [20]: from typing import NamedTuple
    ...:
    ...: class UserBase(NamedTuple):
    ...:     id: int
    ...:     name: str
    ...:     age: int
    ...:     belongs: str
    ...:
    ...: class User(UserBase):
    ...:     def __new__(cls, profile):

iisaka51

In [1]: from datajuggler import serializer as io

In [2]: from dataclasses import dataclass, field
   ...:
   ...: @dataclass
   ...: class User:
   ...:     id: int = field(init=False)
   ...:     name: str = field(init=False)
   ...:     age: int = field(init=False)
   ...:     belongs: str = field(init=False)

iisaka51

In [1]: from datajuggler import serializer as io

In [2]: from datajuggler import aDict

In [3]: class User(aDict):
   ...:     pass
   ...:

In [4]: users = io.read_contents('sqlite:///users.sqlite#users',row_type=User)

iisaka51

In [8]: users[0].freeze()

In [9]: try:
   ...:     users[0].age=20
   ...: except AttributeError as e:
   ...:     print(e)
   ...:
User frozen object cannot be modified.

In [10]: