Hi all,
can anyone explain the behaviour of the following code sniplet:
---schnipp <---
class Base(object):
def __init__( self, lst=[] ):
self.varlist = lst
def addVar( self, var ):
self.varlist.append(var)
class Derived(Base):
def __init__( self, var ):
Base.__init__(self)
self.addVar(var)
vars = ['foo', 'bar']
for ivar in vars:
obj = Derived(ivar)
print ivar, obj, obj.varlist
---schnapp <---
After running (Python 2.5.1), I get the following output:
foo <__main__.Derived object at 0xb7c608cc['foo']
bar <__main__.Derived object at 0xb7c6092c['foo', 'bar']
So, I get two different objects, but how does the 'foo' get into the second
varlist? I'm a little bit confused about this, any ideas?
Thanks in advance
Jan 2 1008
Jan Schäfer wrote:
can anyone explain the behaviour of the following code sniplet:
well, it *is* explained in the tutorial, the language reference, and the
FAQ, so yes, it can be explained ;-)
for more information, see this page: http://effbot.org/zone/default-values.htm
</F>
On 7 sep, 12:40, Fredrik Lundh <fred...@pythonware.comwrote:
Jan Schäfer wrote:
can anyone explain the behaviour of the following code sniplet:
well, it *is* explained in the tutorial, the language reference, and the
FAQ, so yes, it can be explained ;-)
for more information, see this page:
http://effbot.org/zone/default-values.htm
</F>
Well, you may want replace the last line by:
print ivar, obj, obj.varlist, id(obj.varlist)
To have another behavior, you may want replace the 3 first lines by:
class Base(object):
def __init__( self, lst=None ):
if lst is None: lst=[]
self.varlist = lst
Enjoy Python ! This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics
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