A bug in python?

[Xavieran]

I'm running python 2.5.2 and I think I may have found a bug...

When I run:
isinstance(True,int)

python returns True...
it also returns true when I substitute False for True...

Is this a bug?
Or was this intended?

[Delever]

The Boolean type is a subclass of the int class so that arithmetic using a Boolean still works.

[Xavieran]

Seems a bit strange though, In my app I need to distuinguish between int and bool...

def opposite(x):
'''Return the opposite of x.'''
if x:
if isinstance(x,bool):return False
elif isinstance(x,int):return 0

else:
if isinstance(x,bool):return True
elif isinstance(x,int):return 1

I've switched the order of ifs so it works correctly...
But it seems rather strange...:confused:

[geirha]

I don't understand why you have to distinguish between bool and int. They are both ints ...
>>> True+True
2

[ghostdog74]

I'm running python 2.5.2 and I think I may have found a bug...

When I run:
isinstance(True,int)

python returns True...
it also returns true when I substitute False for True...

Is this a bug?
Or was this intended?

True has value of 1, False is 0. So what is wrong that you think its wrong?

[slavik]

err, shouldn't true+true be invalid in Python since it isn't duck typed?

[Delever]

err, shouldn't true+true be invalid in Python since it isn't duck typed?

This is good read if you are interested:

http://www.python.org/dev/peps/pep-0285/

[loell]

maybe use isnum? or sumpin equivalent.

[slavik]

This is good read if you are interested:

http://www.python.org/dev/peps/pep-0285/
thanks for the link ... it clears up the decision up a bit ...

[loell]

maybe use isnum? or sumpin equivalent.

def isnum(x) :
# """Return true if x is a number."""
try :
return complex(x) == x
except Exception :
return False