in java, the following code defines an array of the predefined class (myCls):
myCls arr[] = new myCls
how can I do that in python? I want to have an array of type (myCls)?
thanks in advance
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Duplicate: stackoverflow.com/questions/1924469/define-a-list-with-typeS.Lott– S.Lott2009-12-27 14:58:46 +00:00Commented Dec 27, 2009 at 14:58
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2 Answers
Python is dynamically typed. You do not need to (and in fact CAN'T) create a list that only contains a single type:
arr = list()
arr = []
If you require it to only contain a single type then you'll have to create your own list-alike, reimplementing the list methods and __setitem__() yourself.
answered Dec 27, 2009 at 10:54
Ignacio Vazquez-Abrams
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5 Comments
catchmeifyoutry
but you CAN create arrays of only integers, double, etc. types in python
Georg Schölly
I don't think that the OP cares about the difference between arrays and lists.
bayer
The statement that you cannot is false, however.
Ignacio Vazquez-Abrams
No, it isn't. list does not care what class it contains. Yes, you can create a list-alike that only accepts a single type, or use array.array, but neither of those is a list.
tzot
@Ignacio: indeed your "CAN'T" statement as specified is false. In python, you CAN create a list that contains items of a single type; what you can't, is you CAN'T ENFORCE the list items to be of a single type.
You can only create arrays of only a single type using the array package, but it is not designed to store user-defined classes.
The python way would be to just create a list of objects:
a = [myCls() for _ in xrange(10)]
You might want to take a look at this stackoverflow question.
NOTE:
Be careful with this notation, IT PROBABLY DOES NOT WHAT YOU INTEND:
a = [myCls()] * 10
This will also create a list with ten times a myCls object, but it is ten times THE SAME OBJECT, not ten independently created objects.
