Getting the class name of an instance?
PythonIntrospectionInstanceofPython DatamodelPython Problem Overview
How do I find out a name of class that created an instance of an object in Python if the function I am doing this from is the base class of which the class of the instance has been derived?
Was thinking maybe [the inspect module][1] might have helped me out here, but it doesn't seem to give me what I want. And short of parsing the __class__
member, I'm not sure how to get at this information.
[1]: https://docs.python.org/2/library/inspect.html "inspect — Inspect live objects"
Python Solutions
Solution 1 - Python
Have you tried the __name__
attribute of the class? ie type(x).__name__
will give you the name of the class, which I think is what you want.
>>> import itertools
>>> x = itertools.count(0)
>>> type(x).__name__
'count'
If you're still using Python 2, note that the above method works with new-style classes only (in Python 3+ all classes are "new-style" classes). Your code might use some old-style classes. The following works for both:
x.__class__.__name__
Solution 2 - Python
Do you want the name of the class as a string?
instance.__class__.__name__
Solution 3 - Python
type()
?
>>> class A:
... def whoami(self):
... print(type(self).__name__)
...
>>>
>>> class B(A):
... pass
...
>>>
>>>
>>> o = B()
>>> o.whoami()
'B'
>>>
Solution 4 - Python
class A:
pass
a = A()
str(a.__class__)
The sample code above (when input in the interactive interpreter) will produce '__main__.A'
as opposed to 'A'
which is produced if the __name__
attribute is invoked. By simply passing the result of A.__class__
to the str
constructor the parsing is handled for you. However, you could also use the following code if you want something more explicit.
"{0}.{1}".format(a.__class__.__module__,a.__class__.__name__)
This behavior can be preferable if you have classes with the same name defined in separate modules.
The sample code provided above was tested in Python 2.7.5.
Solution 5 - Python
In Python 2,
type(instance).__name__ != instance.__class__.__name__
# if class A is defined like
class A():
...
type(instance) == instance.__class__
# if class A is defined like
class A(object):
...
Example:
>>> class aclass(object):
... pass
...
>>> a = aclass()
>>> type(a)
<class '__main__.aclass'>
>>> a.__class__
<class '__main__.aclass'>
>>>
>>> type(a).__name__
'aclass'
>>>
>>> a.__class__.__name__
'aclass'
>>>
>>> class bclass():
... pass
...
>>> b = bclass()
>>>
>>> type(b)
<type 'instance'>
>>> b.__class__
<class __main__.bclass at 0xb765047c>
>>> type(b).__name__
'instance'
>>>
>>> b.__class__.__name__
'bclass'
>>>
Solution 6 - Python
Alternatively you can use the classmethod
decorator:
class A:
@classmethod
def get_classname(cls):
return cls.__name__
def use_classname(self):
return self.get_classname()
Usage:
>>> A.get_classname()
'A'
>>> a = A()
>>> a.get_classname()
'A'
>>> a.use_classname()
'A'
Solution 7 - Python
Good question.
Here's a simple example based on GHZ's which might help someone:
>>> class person(object):
def init(self,name):
self.name=name
def info(self)
print "My name is {0}, I am a {1}".format(self.name,self.__class__.__name__)
>>> bob = person(name='Robert')
>>> bob.info()
My name is Robert, I am a person
Solution 8 - Python
Apart from grabbing the special __name__
attribute, you might find yourself in need of the qualified name for a given class/function. This is done by grabbing the types __qualname__
.
In most cases, these will be exactly the same, but, when dealing with nested classes/methods these differ in the output you get. For example:
class Spam:
def meth(self):
pass
class Bar:
pass
>>> s = Spam()
>>> type(s).__name__
'Spam'
>>> type(s).__qualname__
'Spam'
>>> type(s).Bar.__name__ # type not needed here
'Bar'
>>> type(s).Bar.__qualname__ # type not needed here
'Spam.Bar'
>>> type(s).meth.__name__
'meth'
>>> type(s).meth.__qualname__
'Spam.meth'
Since introspection is what you're after, this is always you might want to consider.
Solution 9 - Python
You can simply use __qualname__
which stands for qualified name of a function or class
Example:
>>> class C:
... class D:
... def meth(self):
... pass
...
>>> C.__qualname__
'C'
>>> C.D.__qualname__
'C.D'
>>> C.D.meth.__qualname__
'C.D.meth'
documentation link qualname
Solution 10 - Python
To get instance classname:
type(instance).__name__
or
instance.__class__.__name__
both are the same