Is implicit underscore assignment documented anywhere? I've seen
reference to this, and it seems to be simply that, when Python
interactively prints a value in response to a user entering an expression,
that value is assigned to the variable _.
As far as I can tell, the following transcript shows its workings:
ActivePython 2.4.3 Build 12 (ActiveState Software Inc.) based on
Python 2.4.3 (#69, Apr 11 2006, 15:32:42) [MSC v.1310 32 bit (Intel)] on win32
Type help, copyright, credits or license for more information.
_
Traceback (most recent call last):
File stdin, line 1, in ?
NameError: name '_' is not defined
a = 0
_
Traceback (most recent call last):
File stdin, line 1, in ?
NameError: name '_' is not defined
a
0
_
0
a = 5
_
0
a
5
_
5
a = 5
_
0
a
5
_
5
#value unchanged, because a's value was not printed (the interpreter
does not print None).
...
a = 10
print a
10
_
5
# value unchanged, because print is a statement, not an expression.
...
Is this documented anywhere?
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