newbee I have an object how to check what's his class?

[consternation]

I can't find neither in tutorial nor with google It's all about
isinstance, or __class__.
How to test that an object is an instance of my X class??
Do I have this problems because I stre my objects in a dict?

I wrote a class X like this :
class X(object):

def __init__(self,n ame):
self.name=name
self.val=[]
self.descriptio n ="class X contains : "

def __repr__(self):
for i in range(len(self. val)):
description+=i
return self.descriptio n


In class Y I create my X objects and put them into a dict

print "\nTEST"
..for (i,v) in self.mem.items( ):
print v

The objects are printed out the way I specified in __repr__, so I know it's
an object of X class.
No I want to put in the dict some other objects of class Z,K....
When I get the value fom dict I have to distinguish them somehow to handle
them latr in programm.
I thouth about isinstanceof - it doesn't work. I did some tests, but I
don't understand the answers:
Why python claims it's a list, but still print's it like X class
#in Y class:
print isinstance(v,X) False
print v.__class__.__n ame__ list


And adding print in X class i see
def __repr__(self):
print self.__class__ -- [__main__.Comple x

Could someone explain this to me?
thank you

[paul.keating@nibc.com]

Re: newbee I have an object how to check what's his class?

This doesn't answer your whole post because it asked a lot of
questions. But as to finding out whether something is an instance of a
class:

class X(object):
# ... defined as in your post

>>x = X('Fred')
>>x

class X contains:

>>type(x) is X

True

>>isinstance(x, X)

True

>>x.__class__._ _name__

'X'

Now for subclasses:

class Y(X):
extrastuffinY = 1

>>y = Y('Joe')
>>type(y) is X

False

>>isinstance(y, X)

True


consternation:

I can't find neither in tutorial nor with google It's all about
isinstance, or __class__.
How to test that an object is an instance of my X class??

[consternation]

Re: newbee I have an object how to check what's his class?

Thank You for reply but ....
I found solution suggested by You in a tutorial yesterday. For some reason
it doesn't work in my case.

code:
#mem-dictionary in Y class for storing objects
#Y doesn't inherit from X
for (i,v) in self.mem.items( ):
print " isinstance(x,X) "
print isinstance(v,X)
print "type(x) is X"
print type(v) is X
print v.__class__.__n ame__
print v.__class__

result:
isinstance(x,X)
False
type(x) is X
False
<type 'list'>
list

Well I can handle my problem. I will give an extra field in class with it's
name. But I thought that when a language has tools to learn a class of an
object one should use it.


paul.keating@ni bc.com wrote:

This doesn't answer your whole post because it asked a lot of
questions. But as to finding out whether something is an instance of a
class:
>
class X(object):
# ... defined as in your post
>

>>>x = X('Fred')
>>>x

class X contains:

>>>type(x) is X

True

>>>isinstance(x ,X)

True

>>>x.__class__. __name__

'X'
>
Now for subclasses:
>
class Y(X):
extrastuffinY = 1
>

>>>y = Y('Joe')
>>>type(y) is X

False

>>>isinstance(y ,X)

True
>
>
consternation:
>

>I can't find neither in tutorial nor with google It's all about
>isinstance, or __class__.
>How to test that an object is an instance of my X class??

[Marc 'BlackJack' Rintsch]

Re: newbee I have an object how to check what's his class?

In <ej2b34$9nk$1@u ltra60.mat.uni. torun.pl>, consternation wrote:

Thank You for reply but ....
I found solution suggested by You in a tutorial yesterday. For some reason
it doesn't work in my case.
>
code:
#mem-dictionary in Y class for storing objects
#Y doesn't inherit from X
for (i,v) in self.mem.items( ):
print " isinstance(x,X) "
print isinstance(v,X)
print "type(x) is X"
print type(v) is X
print v.__class__.__n ame__
print v.__class__
>
result:
isinstance(x,X)
False
type(x) is X
False
<type 'list'>
list

Define "doesn't work". Obviously lists are not instances of your `X`
class. So where's the problem? What did you expect and why?

Ciao,
Marc 'BlackJack' Rintsch

[consternation]

Re: newbee I have an object how to check what's his class?


I think I know now where my problems come from. I spare you boring
implementation code.
The case look like this: I parse xml file something a like
<X id="0">
<a>1 <\a>
<a2 <\a>

<X id="1">
<a>3 <\a>
<b4<\b>
<\X>
</X>

<X id="2">
<a <\a>
<a <\a>

<X id="3">
<a<\a>
<b<\b>
<\X>
</X>
I succesfully constructlop-level X objects - I see all components when i
print X0, X1 out with _repr_.
I store my X's in memory. I had some problems with this. I googled, red
newsgoup ad foud a solution that seemd to be perfect for me (...till now).
In the parser- Y class a have a dictionary
def __init__
self.mem={}
I googled a way how to add elements to dict, I have read the code not the
description below
##copied from http://aspn.activestate.com/ASPN/Coo...n/Recipe/66516
def addItem(self,wo rd,pagenumber):
self.mem.setdef ault(word,[]).append(pagenu mber)
^^^^^^^^
So my dict looks like{
(id of top-level X) 0 : (the X itself) X0,
2 : X2,
4..........
}
I wrote it some time and I was tired I haven't pay attention to the
breackets at he beginning of outprint
TOP LEVEL X WITH ID=0
[<class X<----
<a>1<\a>
<a>2<\a>
<class X>
<a >3<\a>
<a4<\a>
<\class X>
<\class X>]
One can clearly see it's a list :( Shame on me.
I did a trick. If my X object is stored in a list and it's the only element
of the list I can simply use it like:
print v[0]
print" isinstance(x,X) "
print isinstance(v[0],X)
print "type(x) is X"
print type(v[0]) is X
print v[0].__class__
print v[0].__class__.__na me__
and results
<class X<----no [!!!!
<a>1<\a>
<a>2<\a>
<class X>
<a >3<\a>
<a4<\a>
<\class X>
<\class X>

isinstance(x,X)
True :-)
type(x) is X
False :( ??
__main__.X
X
temporarily it solves my probblems I'm just curious why type can't handle
the test.
Thank you for help, and making me think :-)

[Gabriel Genellina]

Re: newbee I have an object how to check what's his class?

At Friday 10/11/2006 18:05, consternation wrote:

>def __init__
self.mem={}
>I googled a way how to add elements to dict, I have read the code not the
>description below

self.mem[key] = value

I strongly suggest you read some introductory Python docs, like
http://docs.python.org/tut/tut.html or http://www.diveintopython.org

>isinstance(x,X )
>True :-)
>type(x) is X
>False :( ??
>__main__.X
>X
temporarily it solves my probblems I'm just curious why type can't handle
>the test.

You still didn't show enough code, but I bet that X is an old-style
class, that is, you wrote:
class X: blablabla
instead of
class X(object): blablabla
For old-style class instances, type(x) is InstanceType, not the actual class.


--
Gabriel Genellina
Softlab SRL

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