Полезные встроенные функции

Работа с атрибутами объекта

Функции hasattr, getattr, delattr, setattr.

hasattr:

class Test:
    def __init__(self, name):
        self.name = name

    def method1(self):
        print("method1")


In [7]: t1 = Test("object1")

In [8]: hasattr(t1, "name")
Out[8]: True

In [9]: hasattr(t1, "test")
Out[9]: False

In [10]: hasattr(t1, "method1")
Out[10]: True

getattr

In [11]: getattr(t1, "method1")
Out[11]: <bound method Test.method1 of <__main__.Test object at 0xb5213ef8>>

In [12]: getattr(t1, "name")
Out[12]: 'object1'

In [13]: getattr(t1, "test")
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-13-200257dcfffb> in <module>
----> 1 getattr(t1, "test")

AttributeError: 'Test' object has no attribute 'test'

In [14]: getattr(t1, "test", None)

In [15]: getattr(t1, "test", False)
Out[15]: False

setattr

In [16]: setattr(t1, "test", False)

In [17]: t1.test
Out[17]: False

delattr

In [19]: delattr(t1, "test")

In [20]: t1.test
---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
<ipython-input-20-8ad1d771f5eb> in <module>
----> 1 t1.test

AttributeError: 'Test' object has no attribute 'test'

vars

class Test:
    def __init__(self, name):
        self.name = name

    def method1(self):
        print("method1")

In [22]: vars(Test)
Out[22]:
mappingproxy({'__module__': '__main__',
              '__init__': <function __main__.Test.__init__(self, name)>,
              'method1': <function __main__.Test.method1(self)>,
              '__dict__': <attribute '__dict__' of 'Test' objects>,
              '__weakref__': <attribute '__weakref__' of 'Test' objects>,
              '__doc__': None})

In [23]: t1 = Test("object1")

In [24]: vars(t1)
Out[24]: {'name': 'object1'}

isinstance, issubclass

In [39]: from collections.abc import Iterator, Iterable

In [40]: vlans = [1, 2, 3]

In [41]: isinstance(vlans, list)
Out[41]: True

In [42]: isinstance(vlans, Iterable)
Out[42]: True

In [43]: isinstance(vlans, Iterator)
Out[43]: False

callable

def summ(a, b):
    print(locals())
    return a + b


In [36]: callable(summ)
Out[36]: True

In [37]: callable(Test)
Out[37]: True

In [38]: callable(t1)
Out[38]: False

dir

class Test:
    def __init__(self, name):
        self.name = name

    def method1(self):
        print("method1")


In [34]: dir(Test)
Out[34]:
['__class__',
 '__delattr__',
 '__dict__',
 '__dir__',
 '__doc__',
 '__eq__',
 '__format__',
 '__ge__',
 '__getattribute__',
 '__gt__',
 '__hash__',
 '__init__',
 '__init_subclass__',
 '__le__',
 '__lt__',
 '__module__',
 '__ne__',
 '__new__',
 '__reduce__',
 '__reduce_ex__',
 '__repr__',
 '__setattr__',
 '__sizeof__',
 '__str__',
 '__subclasshook__',
 '__weakref__',
 'method1']

eval, exec

eval

In [29]: eval("10 + 5")
Out[29]: 15

exec

upper_func = """
def upper(string):
    return string.upper()
"""

In [31]: exec(upper_func)

In [32]: upper("test")
Out[32]: 'TEST'

locals, globals

globals

In [25]: globals()
Out[25]:
{'__name__': '__main__',
 '__doc__': 'Automatically created module for IPython interactive environment',
 '__package__': None,
 '__loader__': None,
 '__spec__': None,
 '__builtin__': <module 'builtins' (built-in)>,
 '__builtins__': <module 'builtins' (built-in)>,
 ...

locals

def summ(a, b):
    print(locals())
    return a + b


In [28]: summ(3, 4)
{'a': 3, 'b': 4}
Out[28]: 7