Thanks! I went with extend and generator expression as I *am* dealing with rather a lot of data. Now I think I'm going to go on a little hunt through my code looking for more places where I should replace list comprehensions with generator expressions - bit of a newbie here.
On Mar 25, 3:57 pm, Steven D'Aprano <[EMAIL PROTECTED]> wrote: > On Sat, 24 Mar 2007 23:43:10 -0700, bullockbefriending bard wrote: > > z_list = [Z(y.var1, y.var2,..) for y in list_of_objects_of_class_Y] > > > Of course this just gives me a plain list and no access to the > > methodsof z_list. > > List comprehensions give you a list. If you want to convert that list into > the type of z_list, you need to do it yourself. Since ZList sub-classes > from list, probably the easiest way is just: > > z_list = ZList([some list comprehension here]) > > > I could, of course go and write a static method in > > ZList which takes a plain list of Z objects and returns a ZList. > > Yes, that would be one such way. Another way is: > > z_list.extend([some list comprehension here]) > > If you are using a recent enough version of Python, you probably don't > even need the list comprehension. Just use a generator expression: > > z_list.extend(Z(y.var1, y.var2,..) for y in list_of_objects_of_class_Y) > > That's especially useful if the list of objects is huge, because it avoids > creating the list twice: once in the list comp, and once as z_list. > > -- > Steven. -- http://mail.python.org/mailman/listinfo/python-list
