On 31/10/2020 16:20, Chris Angelico wrote:
On Sat, Oct 31, 2020 at 1:51 PM Jon Ribbens via Python-list
<python-list@python.org> wrote:
On 2020-10-31, Stefan Ram <r...@zedat.fu-berlin.de> wrote:
Siddhharth Choudhary <siddharth654choudh...@gmail.com> writes:
I want to know why x+=1 does not return the value of the variable.
Which value? The old or the new one?
Expressions never return values.
Except when they're assignment expressions, when they do.
Expressions DO have values, but assignment is a statement, not an
expression. (Assignment expressions don't have augmented forms, so
there's no ambiguity.)
So, you've already realised that:
>>> x = 1
>>> print( x += 2 )
File "<stdin>", line 1
print( x += 2 )
isn't going to work.
However it is possible to achieve something of what you ask (Python
3.8+), using the 'walrus operator' in/as an assignment-expression:
>>> x = 1
>>> print( x := x + 2 )
3
but as others have said, an augmented-expression is not a "named
expression". Accordingly, the more usual walrus application will be
something like:
>>> if ( x := 1 + 2 ) > 1.5:
... print( f"Yes! { x }" )
... else:
... print( f"No! { x } <= 1.5" )
...
Yes! 3
Documented in the manual at
https://docs.python.org/3/reference/expressions.html?highlight=walrus#assignment-expressions
Read more at https://www.python.org/dev/peps/pep-0572/
Free advice: whatever you do, don't call @Chris a walrus!
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Regards =dn
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