Is it possible to return a value while still modifying it?
Well honestly no easy way for me to lamens the title of this question, basically is there a way to modify a return value for a function while also returning it in the same line.
Example - custom implementation of an iterable class
I’d like to replace this:
def __next__(self):
if self.count <= 0:
raise StopIteration
r = self.count
self.count -= 1
return r
With this:
def __next__(self):
if self.count <= 0:
raise StopIteration
return self.count -= 1
Honestly, I know this may seem frivolous (which it may be) but I’m only this because I’m a fan of one-liners and this boils down to making even a process as simple as this more logically readable; plus, depending on the implementation, it would nullify having to hold the value r in memory (I know I know, removing the need for r has no significant gain but hey I’m only asking if this is possible).
I know I’ve only given one example but this happens to be the only case I can think of that something like this Would be needed. Python is a wonderful language full of many special things like += being a “wrapper” of __iadd__ my thing is am I missing something? Or is this possible... and why must it be used as a single line and not in conjunction with a return statement as it doesn’t return its altered value?
python python-3.x
asked Nov 23 at 6:29
Jaba
6,821175293
add a comment |
Well honestly no easy way for me to lamens the title of this question, basically is there a way to modify a return value for a function while also returning it in the same line.
Example - custom implementation of an iterable class
I’d like to replace this:
def __next__(self):
if self.count <= 0:
raise StopIteration
r = self.count
self.count -= 1
return r
With this:
def __next__(self):
if self.count <= 0:
raise StopIteration
return self.count -= 1
Honestly, I know this may seem frivolous (which it may be) but I’m only this because I’m a fan of one-liners and this boils down to making even a process as simple as this more logically readable; plus, depending on the implementation, it would nullify having to hold the value r in memory (I know I know, removing the need for r has no significant gain but hey I’m only asking if this is possible).
I know I’ve only given one example but this happens to be the only case I can think of that something like this Would be needed. Python is a wonderful language full of many special things like += being a “wrapper” of __iadd__ my thing is am I missing something? Or is this possible... and why must it be used as a single line and not in conjunction with a return statement as it doesn’t return its altered value?
python python-3.x
asked Nov 23 at 6:29
Jaba
6,821175293
"depending on the implementation, it would nullify having to hold the value r in memory" - you really shouldn't try to optimize based on speculation like that. As a matter of fact, no, it would not prevent having to hold the value in memory, even if syntax like this existed. (Also, in every language I know wherereturn x -= ysyntax exists, the value returned is the value after subtraction, not before.)
– user2357112
Nov 23 at 6:55
Also, the method is__next__on Python 3.
– user2357112
Nov 23 at 6:57
Basically, why can’tval += ireturn it’s altered value then? Seems to me this should be viable.
– Jaba
Nov 23 at 6:59
One-liners are overrated. In Python, an assignment is not an expression, so you can't do that sort of thing. This was a deliberate design decision to prevent the hard-to-read nested assignments that C allows.
– PM 2Ring
Nov 23 at 7:16
But, but I like those nested assignments. Shorter the better. Either way it’s nothing I’m hung up on I just prefer shorter code on simpler tasks
– Jaba
Nov 23 at 7:22
add a comment |
Well honestly no easy way for me to lamens the title of this question, basically is there a way to modify a return value for a function while also returning it in the same line.
Example - custom implementation of an iterable class
I’d like to replace this:
def __next__(self):
if self.count <= 0:
raise StopIteration
r = self.count
self.count -= 1
return r
With this:
def __next__(self):
if self.count <= 0:
raise StopIteration
return self.count -= 1
Honestly, I know this may seem frivolous (which it may be) but I’m only this because I’m a fan of one-liners and this boils down to making even a process as simple as this more logically readable; plus, depending on the implementation, it would nullify having to hold the value r in memory (I know I know, removing the need for r has no significant gain but hey I’m only asking if this is possible).
I know I’ve only given one example but this happens to be the only case I can think of that something like this Would be needed. Python is a wonderful language full of many special things like += being a “wrapper” of __iadd__ my thing is am I missing something? Or is this possible... and why must it be used as a single line and not in conjunction with a return statement as it doesn’t return its altered value?
python python-3.x
asked Nov 23 at 6:29
Jaba
6,821175293
Well honestly no easy way for me to lamens the title of this question, basically is there a way to modify a return value for a function while also returning it in the same line.
Example - custom implementation of an iterable class
I’d like to replace this:
def __next__(self):
if self.count <= 0:
raise StopIteration
r = self.count
self.count -= 1
return r
With this:
def __next__(self):
if self.count <= 0:
raise StopIteration
return self.count -= 1
Honestly, I know this may seem frivolous (which it may be) but I’m only this because I’m a fan of one-liners and this boils down to making even a process as simple as this more logically readable; plus, depending on the implementation, it would nullify having to hold the value r in memory (I know I know, removing the need for r has no significant gain but hey I’m only asking if this is possible).
I know I’ve only given one example but this happens to be the only case I can think of that something like this Would be needed. Python is a wonderful language full of many special things like += being a “wrapper” of __iadd__ my thing is am I missing something? Or is this possible... and why must it be used as a single line and not in conjunction with a return statement as it doesn’t return its altered value?
python python-3.x
python python-3.x
asked Nov 23 at 6:29
Jaba
6,821175293
asked Nov 23 at 6:29
Jaba
6,821175293
edited Nov 23 at 7:00
asked Nov 23 at 6:29
Jaba
6,821175293
asked Nov 23 at 6:29
Jaba
6,821175293
asked Nov 23 at 6:29
Jaba
6,821175293
6,821175293
"depending on the implementation, it would nullify having to hold the value r in memory" - you really shouldn't try to optimize based on speculation like that. As a matter of fact, no, it would not prevent having to hold the value in memory, even if syntax like this existed. (Also, in every language I know wherereturn x -= ysyntax exists, the value returned is the value after subtraction, not before.)
– user2357112
Nov 23 at 6:55
Also, the method is__next__on Python 3.
– user2357112
Nov 23 at 6:57
Basically, why can’tval += ireturn it’s altered value then? Seems to me this should be viable.
– Jaba
Nov 23 at 6:59
One-liners are overrated. In Python, an assignment is not an expression, so you can't do that sort of thing. This was a deliberate design decision to prevent the hard-to-read nested assignments that C allows.
– PM 2Ring
Nov 23 at 7:16
But, but I like those nested assignments. Shorter the better. Either way it’s nothing I’m hung up on I just prefer shorter code on simpler tasks
– Jaba
Nov 23 at 7:22
add a comment |
"depending on the implementation, it would nullify having to hold the value r in memory" - you really shouldn't try to optimize based on speculation like that. As a matter of fact, no, it would not prevent having to hold the value in memory, even if syntax like this existed. (Also, in every language I know wherereturn x -= ysyntax exists, the value returned is the value after subtraction, not before.)
– user2357112
Nov 23 at 6:55
Also, the method is__next__on Python 3.
– user2357112
Nov 23 at 6:57
Basically, why can’tval += ireturn it’s altered value then? Seems to me this should be viable.
– Jaba
Nov 23 at 6:59
One-liners are overrated. In Python, an assignment is not an expression, so you can't do that sort of thing. This was a deliberate design decision to prevent the hard-to-read nested assignments that C allows.
– PM 2Ring
Nov 23 at 7:16
But, but I like those nested assignments. Shorter the better. Either way it’s nothing I’m hung up on I just prefer shorter code on simpler tasks
– Jaba
Nov 23 at 7:22
"depending on the implementation, it would nullify having to hold the value r in memory" - you really shouldn't try to optimize based on speculation like that. As a matter of fact, no, it would not prevent having to hold the value in memory, even if syntax like this existed. (Also, in every language I know where
return x -= y syntax exists, the value returned is the value after subtraction, not before.)– user2357112
Nov 23 at 6:55
"depending on the implementation, it would nullify having to hold the value r in memory" - you really shouldn't try to optimize based on speculation like that. As a matter of fact, no, it would not prevent having to hold the value in memory, even if syntax like this existed. (Also, in every language I know where
return x -= y syntax exists, the value returned is the value after subtraction, not before.)– user2357112
Nov 23 at 6:55
Also, the method is
__next__ on Python 3.– user2357112
Nov 23 at 6:57
Also, the method is
__next__ on Python 3.– user2357112
Nov 23 at 6:57
Basically, why can’t
val += i return it’s altered value then? Seems to me this should be viable.– Jaba
Nov 23 at 6:59
Basically, why can’t
val += i return it’s altered value then? Seems to me this should be viable.– Jaba
Nov 23 at 6:59
One-liners are overrated. In Python, an assignment is not an expression, so you can't do that sort of thing. This was a deliberate design decision to prevent the hard-to-read nested assignments that C allows.
– PM 2Ring
Nov 23 at 7:16
One-liners are overrated. In Python, an assignment is not an expression, so you can't do that sort of thing. This was a deliberate design decision to prevent the hard-to-read nested assignments that C allows.
– PM 2Ring
Nov 23 at 7:16
But, but I like those nested assignments. Shorter the better. Either way it’s nothing I’m hung up on I just prefer shorter code on simpler tasks
– Jaba
Nov 23 at 7:22
But, but I like those nested assignments. Shorter the better. Either way it’s nothing I’m hung up on I just prefer shorter code on simpler tasks
– Jaba
Nov 23 at 7:22
add a comment |
2 Answers
2
active
oldest
votes
It's because -= modifies the variable, and do any thing to that, (like now you returned that) will raise errors.
Demo:
>>> a=3
>>> a+(a+=1)
SyntaxError: invalid syntax
>>> # also to show that it does modify the variable:
>>> a=3
>>> a+=1
>>> a
4
>>>
Update:
You do a two-liner:
def f(a):
if a<=0:raise StopIteration
a-=1;return a
answered Nov 23 at 6:43
U9-Forward
12.5k21136
@Jaba i edited mine, Btw, you received my email?
– U9-Forward
Nov 23 at 6:54
1
Yes, thanks! I will respond later
– Jaba
Nov 23 at 7:01
1
Ok, now that’s more my liking, look at that simplicity
– Jaba
Nov 23 at 7:19
@Jaba Happy to help, :-), 😊😊😊, (just got back to stackoverflow)
– U9-Forward
Nov 24 at 23:39
@Jaba Haven't so a reply yet as promised :-), tho you can answer anytime, lol :D, 😜
– U9-Forward
Nov 28 at 4:05
add a comment |
return foobar -= 1
or
>>> a = 3
>>> b = (a += 1)
File "<stdin>", line 1
b = (a += 1)
^
SyntaxError: invalid syntax
is not possible in Python.
Although the first solution needs to store one more variable for this timestep (or do one operation more), to cite the Python Zen: Readability counts.
answered Nov 23 at 6:35
Martin Thoma
40.5k53290509
I understand thatreturn foo-=1isn’t possible, I’m asking if there is a way to accomplish this without being as verbose as my first example. I just feelreturn foo-=1is easily readable but less verbose than the later
– Jaba
Nov 23 at 6:48
add a comment |
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2 Answers
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active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
It's because -= modifies the variable, and do any thing to that, (like now you returned that) will raise errors.
Demo:
>>> a=3
>>> a+(a+=1)
SyntaxError: invalid syntax
>>> # also to show that it does modify the variable:
>>> a=3
>>> a+=1
>>> a
4
>>>
Update:
You do a two-liner:
def f(a):
if a<=0:raise StopIteration
a-=1;return a
answered Nov 23 at 6:43
U9-Forward
12.5k21136
@Jaba i edited mine, Btw, you received my email?
– U9-Forward
Nov 23 at 6:54
1
Yes, thanks! I will respond later
– Jaba
Nov 23 at 7:01
1
Ok, now that’s more my liking, look at that simplicity
– Jaba
Nov 23 at 7:19
@Jaba Happy to help, :-), 😊😊😊, (just got back to stackoverflow)
– U9-Forward
Nov 24 at 23:39
@Jaba Haven't so a reply yet as promised :-), tho you can answer anytime, lol :D, 😜
– U9-Forward
Nov 28 at 4:05
add a comment |
It's because -= modifies the variable, and do any thing to that, (like now you returned that) will raise errors.
Demo:
>>> a=3
>>> a+(a+=1)
SyntaxError: invalid syntax
>>> # also to show that it does modify the variable:
>>> a=3
>>> a+=1
>>> a
4
>>>
Update:
You do a two-liner:
def f(a):
if a<=0:raise StopIteration
a-=1;return a
answered Nov 23 at 6:43
U9-Forward
12.5k21136
@Jaba i edited mine, Btw, you received my email?
– U9-Forward
Nov 23 at 6:54
1
Yes, thanks! I will respond later
– Jaba
Nov 23 at 7:01
1
Ok, now that’s more my liking, look at that simplicity
– Jaba
Nov 23 at 7:19
@Jaba Happy to help, :-), 😊😊😊, (just got back to stackoverflow)
– U9-Forward
Nov 24 at 23:39
@Jaba Haven't so a reply yet as promised :-), tho you can answer anytime, lol :D, 😜
– U9-Forward
Nov 28 at 4:05
add a comment |
It's because -= modifies the variable, and do any thing to that, (like now you returned that) will raise errors.
Demo:
>>> a=3
>>> a+(a+=1)
SyntaxError: invalid syntax
>>> # also to show that it does modify the variable:
>>> a=3
>>> a+=1
>>> a
4
>>>
Update:
You do a two-liner:
def f(a):
if a<=0:raise StopIteration
a-=1;return a
answered Nov 23 at 6:43
U9-Forward
12.5k21136
It's because -= modifies the variable, and do any thing to that, (like now you returned that) will raise errors.
Demo:
>>> a=3
>>> a+(a+=1)
SyntaxError: invalid syntax
>>> # also to show that it does modify the variable:
>>> a=3
>>> a+=1
>>> a
4
>>>
Update:
You do a two-liner:
def f(a):
if a<=0:raise StopIteration
a-=1;return a
answered Nov 23 at 6:43
U9-Forward
12.5k21136
edited Nov 23 at 6:54
answered Nov 23 at 6:43
U9-Forward
12.5k21136
answered Nov 23 at 6:43
U9-Forward
12.5k21136
answered Nov 23 at 6:43
U9-Forward
12.5k21136
12.5k21136
@Jaba i edited mine, Btw, you received my email?
– U9-Forward
Nov 23 at 6:54
1
Yes, thanks! I will respond later
– Jaba
Nov 23 at 7:01
1
Ok, now that’s more my liking, look at that simplicity
– Jaba
Nov 23 at 7:19
@Jaba Happy to help, :-), 😊😊😊, (just got back to stackoverflow)
– U9-Forward
Nov 24 at 23:39
@Jaba Haven't so a reply yet as promised :-), tho you can answer anytime, lol :D, 😜
– U9-Forward
Nov 28 at 4:05
add a comment |
@Jaba i edited mine, Btw, you received my email?
– U9-Forward
Nov 23 at 6:54
1
Yes, thanks! I will respond later
– Jaba
Nov 23 at 7:01
1
Ok, now that’s more my liking, look at that simplicity
– Jaba
Nov 23 at 7:19
@Jaba Happy to help, :-), 😊😊😊, (just got back to stackoverflow)
– U9-Forward
Nov 24 at 23:39
@Jaba Haven't so a reply yet as promised :-), tho you can answer anytime, lol :D, 😜
– U9-Forward
Nov 28 at 4:05
@Jaba i edited mine, Btw, you received my email?
– U9-Forward
Nov 23 at 6:54
@Jaba i edited mine, Btw, you received my email?
– U9-Forward
Nov 23 at 6:54
1
1
Yes, thanks! I will respond later
– Jaba
Nov 23 at 7:01
Yes, thanks! I will respond later
– Jaba
Nov 23 at 7:01
1
1
Ok, now that’s more my liking, look at that simplicity
– Jaba
Nov 23 at 7:19
Ok, now that’s more my liking, look at that simplicity
– Jaba
Nov 23 at 7:19
@Jaba Happy to help, :-), 😊😊😊, (just got back to stackoverflow)
– U9-Forward
Nov 24 at 23:39
@Jaba Happy to help, :-), 😊😊😊, (just got back to stackoverflow)
– U9-Forward
Nov 24 at 23:39
@Jaba Haven't so a reply yet as promised :-), tho you can answer anytime, lol :D, 😜
– U9-Forward
Nov 28 at 4:05
@Jaba Haven't so a reply yet as promised :-), tho you can answer anytime, lol :D, 😜
– U9-Forward
Nov 28 at 4:05
add a comment |
return foobar -= 1
or
>>> a = 3
>>> b = (a += 1)
File "<stdin>", line 1
b = (a += 1)
^
SyntaxError: invalid syntax
is not possible in Python.
Although the first solution needs to store one more variable for this timestep (or do one operation more), to cite the Python Zen: Readability counts.
answered Nov 23 at 6:35
Martin Thoma
40.5k53290509
I understand thatreturn foo-=1isn’t possible, I’m asking if there is a way to accomplish this without being as verbose as my first example. I just feelreturn foo-=1is easily readable but less verbose than the later
– Jaba
Nov 23 at 6:48
add a comment |
return foobar -= 1
or
>>> a = 3
>>> b = (a += 1)
File "<stdin>", line 1
b = (a += 1)
^
SyntaxError: invalid syntax
is not possible in Python.
Although the first solution needs to store one more variable for this timestep (or do one operation more), to cite the Python Zen: Readability counts.
answered Nov 23 at 6:35
Martin Thoma
40.5k53290509
I understand thatreturn foo-=1isn’t possible, I’m asking if there is a way to accomplish this without being as verbose as my first example. I just feelreturn foo-=1is easily readable but less verbose than the later
– Jaba
Nov 23 at 6:48
add a comment |
return foobar -= 1
or
>>> a = 3
>>> b = (a += 1)
File "<stdin>", line 1
b = (a += 1)
^
SyntaxError: invalid syntax
is not possible in Python.
Although the first solution needs to store one more variable for this timestep (or do one operation more), to cite the Python Zen: Readability counts.
answered Nov 23 at 6:35
Martin Thoma
40.5k53290509
return foobar -= 1
or
>>> a = 3
>>> b = (a += 1)
File "<stdin>", line 1
b = (a += 1)
^
SyntaxError: invalid syntax
is not possible in Python.
Although the first solution needs to store one more variable for this timestep (or do one operation more), to cite the Python Zen: Readability counts.
answered Nov 23 at 6:35
Martin Thoma
40.5k53290509
answered Nov 23 at 6:35
Martin Thoma
40.5k53290509
answered Nov 23 at 6:35
Martin Thoma
40.5k53290509
answered Nov 23 at 6:35
Martin Thoma
40.5k53290509
40.5k53290509
I understand thatreturn foo-=1isn’t possible, I’m asking if there is a way to accomplish this without being as verbose as my first example. I just feelreturn foo-=1is easily readable but less verbose than the later
– Jaba
Nov 23 at 6:48
add a comment |
I understand thatreturn foo-=1isn’t possible, I’m asking if there is a way to accomplish this without being as verbose as my first example. I just feelreturn foo-=1is easily readable but less verbose than the later
– Jaba
Nov 23 at 6:48
I understand that
return foo-=1 isn’t possible, I’m asking if there is a way to accomplish this without being as verbose as my first example. I just feel return foo-=1 is easily readable but less verbose than the later– Jaba
Nov 23 at 6:48
I understand that
return foo-=1 isn’t possible, I’m asking if there is a way to accomplish this without being as verbose as my first example. I just feel return foo-=1 is easily readable but less verbose than the later– Jaba
Nov 23 at 6:48
add a comment |
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"depending on the implementation, it would nullify having to hold the value r in memory" - you really shouldn't try to optimize based on speculation like that. As a matter of fact, no, it would not prevent having to hold the value in memory, even if syntax like this existed. (Also, in every language I know where
return x -= ysyntax exists, the value returned is the value after subtraction, not before.)– user2357112
Nov 23 at 6:55
Also, the method is
__next__on Python 3.– user2357112
Nov 23 at 6:57
Basically, why can’t
val += ireturn it’s altered value then? Seems to me this should be viable.– Jaba
Nov 23 at 6:59
One-liners are overrated. In Python, an assignment is not an expression, so you can't do that sort of thing. This was a deliberate design decision to prevent the hard-to-read nested assignments that C allows.
– PM 2Ring
Nov 23 at 7:16
But, but I like those nested assignments. Shorter the better. Either way it’s nothing I’m hung up on I just prefer shorter code on simpler tasks
– Jaba
Nov 23 at 7:22