intΒΆ
Python 3’s int
type is very similar to Python 2’s long
, except
for the representation (which omits the L
suffix in Python 2). Python
2’s usual (short) integers have been removed from Python 3, as has the
long
builtin name.
Python 3:
>>> 2**64
18446744073709551616
Python 2:
>>> 2**64
18446744073709551616L
future
includes a backport of Python 3’s int
that
is a subclass of Python 2’s long
with the same representation
behaviour as Python 3’s int
. To ensure an integer is long compatibly with
both Py3 and Py2, cast it like this:
>>> from builtins import int
>>> must_be_a_long_integer = int(1234)
The backported int
object helps with writing doctests and simplifies code
that deals with long
and int
as special cases on Py2. An example is the
following code from xlwt-future
(called by the xlwt.antlr.BitSet
class)
for writing out Excel .xls
spreadsheets. With future
, the code is:
from builtins import int
def longify(data):
"""
Turns data (an int or long, or a list of ints or longs) into a
list of longs.
"""
if not data:
return [int(0)]
if not isinstance(data, list):
return [int(data)]
return list(map(int, data))
Without future
(or with future
< 0.7), this might be:
def longify(data):
"""
Turns data (an int or long, or a list of ints or longs) into a
list of longs.
"""
if not data:
if PY3:
return [0]
else:
return [long(0)]
if not isinstance(data,list):
if PY3:
return [int(data)]
else:
return [long(data)]
if PY3:
return list(map(int, data)) # same as returning data, but with up-front typechecking
else:
return list(map(long, data))