Python Object-oriented programming--Get object information

1.1   Get object Information1.1.1   UseType ()Judging Object Types

>>> type (123)-- basic data type judgment

<class ' int ' >

>>> type (' 123 ')

<class ' str ' >

>>> type (ABS)--python built-in function judgment

<class ' Builtin_function_or_method ' >

>>> type (DOG)

<class ' type ' >

>>> type (Dog ())--The judgment of the custom class, quoted in the Dogclass above

<class ' __main__. Dog ' >

>>> type (123) = = Type (456)

True

>>> type (' 123 ') = = Type (' 456 ') # can be judged in the if

True

determines whether an object is a function, Types constants in the module

>>> importtypes

>>> def fn ():

... pass

...

>>> type (fn) = = types. Functiontype

True

>>> type (ABS) ==types. Builtinfunctiontype

True

>>> type (lambda x:x) ==types. Lambdatype

True

>>> type ((x for x in range) = = types. Generatortype

True

1.1.2   UseIsinstance ()Judging Inheritance

>>> class Animal (object):

... pass

...

>>> class Dog (Animal):

... pass

...

>>> class Erha (DOG):

... pass

...

>>> # Erha inheritance relationship Animal->dog

... a = Animal () # Create an object in turn

>>> B = Dog ()

>>> C = Erha ()

>>>

>>> isinstance(C,ERHA)

True

>>> isinstance (c, Dog)

True

>>> isinstance (c, Animal)

True

>>> Isinstance (b, Dog)

True

>>> Isinstance (b, Animal)

True

>>> Isinstance (b, Erha)

False

can be judged by Type() or by isinstance

>>> Isinstance (123, Int.)

True

>>> isinstance (' a ', str)

True

>>> isinstance ([3], (list, tuple)) -- determine if a variable is one of some types

True

>>> Isinstance ((1, 2, 3), (List,tuple))

True

1.1.3   UseDir ()Get properties and methods for an object

>>> dir (' abc ')-- list properties and methods

[' __add__ ', ' __class__ ', ' __contains__ ', ' __delattr__ ', ' __dir__ ', ' __doc__ ', ' __eq__ ', ' __format__ ', ' __ge__ ', ' __ getattribute__ ', ' __getitem__ ', ' __getnewargs__ ', ' __gt__ ', ' __hash__ ', ' __init__ ', ' __iter__ ', ' __le__ ', ' __len__ ', ' _ _lt__ ', ' __mod__ ', ' __mul__ ', ' __ne__ ', ' __new__ ', ' __reduce__ ', ' __reduce_ex__ ', ' __repr__ ', ' __rmod__ ', ' __rmul__ ', ' _ _setattr__ ', ' __sizeof__ ', ' __str__ ', ' __subclasshook__ ', ' capitalize ', ' casefold ', ' center ', ' count ', ' encode ', ' EndsWith ', ' expandtabs ', ' find ', ' format ', ' Format_map ', ' index ', ' isalnum ', ' isalpha ', ' isdecimal ', ' isdigit ', ' Isidentifier ', ' islower ', ' isnumeric ', ' isprintable ', ' isspace ', ' istitle ', ' isupper ', ' join ', ' ljust ', ' lower ', ' Lstrip ' ', ' Maketrans ', ' partition ', ' replace ', ' rfind ', ' rindex ', ' rjust ', ' rpartition ', ' rsplit ', ' Rstrip ', ' Split ', ' Splitlines ', ' startswith ', ' strip ', ' swapcase ', ' title ', ' Translate ', ' upper ', ' Zfill ']

Mates getattr () , setattr () as well hasattr () , we can manipulate the state of an object directly.

>>> class Myobject (object):

... def __init__ (self):

... self.x = 9

... def power (self):

... return self.x * self.x

...

>>> obj = Myobject ()

>>> hasattr (obj, ' x ') # has attribute ' x '?

True

>>> obj.x

9

>>> getattr (obj, ' x ')

9

>>> hasattr (obj, ' y ') # has attribute ' y '?

False

>>> setattr (obj, ' y ', +) # sets a Y property of 19

>>> getattr (obj, ' y ')

19

>>> OBJ.Y

19

>>> hasattr (obj, ' power ') # have attribute Power(method)?

True

>>> getattr (obj, ' power ') # get Property Power

<bound method Myobject.power of<__main__. Myobject Object at 0x2af174d0bd68>>

Syntaxerror:invalid character Inidentifier

>>> getattr (obj, ' power ') () # get property Power value

81

>>> fn = getattr (obj, ' power ')

>>> fn ()

81

Hasattr 's classic application scenario

Apply the above Myobject () instance

>>> def readpower (obj):

... if hasattr (obj, ' power '):

... return obj.power ()

.. else:

... return None

...

>>> Readpower (Myobject)

Traceback (most recent):

File "<stdin>", line 1, in <module>

File "<stdin>", line 3, in Readpower

Typeerror:power () Missing 1 requiredpositional argument: ' Self '

>>> Myobject (). x

9

>>> Myobject (). Power ()

81

>>> Readpower (Myobject ())

81

This article is from the "90SirDB" blog, be sure to keep this source http://90sirdb.blog.51cto.com/8713279/1826206

Python Object-oriented programming--Get object information