On Fri, Jan 6, 2017 at 1:06 AM, H Krishnan <hetch...@gmail.com> wrote:
> I tried replacing sys.displayhook with a function that does not print
> newline but the newline still got inserted. So, I am not sure where the
> newline is coming from. In any case, I could override sys.displayhook to add
> a newline at the end and that seems to resolve my problem.
In Python 2 the newline is written depending on the value of
sys.stdout.softspace. sys.displayhook initially calls Py_FlushLine, which
resets the file's softspace to 0 via PyFile_SoftSpace and writes a newline if
the previous value was non-zero. Next displayhook writes the repr, sets the
softspace to 1 and calls Py_FlushLine again.
The result you're seeing could occur if your filelike object doesn't have a
dict or a property to allow setting the "softspace" attribute, as the following
toy example demonstrates:
import sys
class File(object):
def __init__(self, file):
self._file = file
self._sp_enabled = True
self.softspace = 0
def write(self, string):
return self._file.write(string)
def __getattribute__(self, name):
value = object.__getattribute__(self, name)
if name == 'softspace':
if not self._sp_enabled:
raise AttributeError
self._file.write('[get softspace <- %d]\n' % value)
return value
def __setattr__(self, name, value):
if name == 'softspace':
if not self._sp_enabled:
raise AttributeError
self._file.write('[set softspace -> %d]\n' % value)
object.__setattr__(self, name, value)
softspace enabled:
>>> sys.stdout = File(sys.stdout)
[set softspace -> 0]
[get softspace <- 0]
[set softspace -> 0]
>>> 42
[get softspace <- 0]
[set softspace -> 0]
42[get softspace <- 0]
[set softspace -> 1]
[get softspace <- 1]
[set softspace -> 0]
[get softspace <- 0]
[set softspace -> 0]
softspace disabled:
>>> sys.stdout._sp_enabled = False
>>> 42
42>>> 42
42>>>
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