Re: Fwd: Possible Addition to Python Language: Marked Sub-condition
Hi Rajeev and others Thanks for your responses. I completely overlooked the simple fact that the conditions are evaluated to boolean values and as such can be stored in variables. In the hindsight there may perhaps be a couple of (far-fetched) merits to my proposal (like useful in conditions with dynamic function calls or sparing users the effort of maintaining rather ephemeral variables) but they are of course not worth the effort of making a change to the language itself. So I am sorry for the spam. Will be careful the next time. Best regards Shrinivas Kulkarni On Mon, Mar 9, 2020 at 10:21 AM Rajeev J Sebastian <rajeev.sebastian@alokin.in> wrote:
Hi Shrinivas,
Wouldn’t these just be variables?
Cond1 = color == Blue and count == 20 Cond2 = color == Red
if cond1 or cond2: Do something elif cond3: Do something else
Regards Rajeev J Sebastian On 8 Mar 2020, 20:42 +0530, Shrinivas Kulkarni <shrinivk@gmail.com>, wrote:
Hello Everyone
While writing python code, I frequently come across the need to do certain tasks based on combined conditions.
Much of the task for all the sub-conditions are common but some are specific to one or more of these sub-conditions.
A simplified example:
########################## Code ########################## if (color == BLUE and count == 20) or (color == RED and count % 5 == 0): rotate_the_wheel() # Common to the two sub-conditions if(color == BLUE and count == 20): # First sub-condition set_signal() if(color == RED and count % 5 == 0): # Second sub-condition clear_signal() proc_post_rotate() # Common to the two sub-conditions
I am not sure if there is a better way to do this. If not, maybe there can be an extension to the language, which would allow marking a sub-condition just like we mark a sub-expression in a regular expression.
Tentative syntax for this could be ({} marks the sub-condition and \number refers back to it):
########################## Code ########################## if {(color == BLUE and count == 20)} or {(color == RED and count % 5 == 0)}: rotate_the_wheel() if(\1): # First marked condition set_signal() if(\2): # Second marked condition unset_signal() proc_post_rotate()
And like sub-expressions, the nesting of marked sub-condions should also be possible:
########################## Code ########################## if {{(color == BLUE and count == 20)} and {value == 20}} or {(color == RED and count % 5 == 0)}: if(\1):# Refers to the entire subcondition {{(color == BLUE and count == 20)} and {value = 20}} proc1() if(\2):# Refers to sub-subcondition {value == 20}
This will not only avoid the repetition of sub-conditions, but make code readable since something like \1 will give an immediate indication of a sub-condition that's defined earlier.
Please let me know something similar is already implemented. Even otherwise, all your thoughts, inputs and criticism are welcome.
Thanks and best regards Shrinivas Kulkarni _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-leave@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/M5OUL4... Code of Conduct: http://python.org/psf/codeofconduct/
So I am sorry for the spam. Will be careful the next time.
I wouldn't worry about it too much. :) In future, if you can establish to some degree that: 1) The feature isn't already available (if you're unsure, try python-list as suggested above) 2) It has some realistic use cases 3) It hasn't been already proposed (if so, prepare counterarguments using past discussions) 4) It doesn't involve major breaking changes (if it does, prepare to strongly justify why it's worth the breakage) If you have the above points covered, then invest some time into thinking about and writing up the post, you're pretty much good to go. Even if the idea is something that will never be implemented, a rejected proposal can often yield a substantial wealth of information or provide a spark of inspiration for a similar idea. On Mon, Mar 9, 2020 at 10:00 AM Shrinivas Kulkarni <shrinivk@gmail.com> wrote:
Hi Rajeev and others
Thanks for your responses. I completely overlooked the simple fact that the conditions are evaluated to boolean values and as such can be stored in variables. In the hindsight there may perhaps be a couple of (far-fetched) merits to my proposal (like useful in conditions with dynamic function calls or sparing users the effort of maintaining rather ephemeral variables) but they are of course not worth the effort of making a change to the language itself.
So I am sorry for the spam. Will be careful the next time.
Best regards Shrinivas Kulkarni
On Mon, Mar 9, 2020 at 10:21 AM Rajeev J Sebastian <rajeev.sebastian@alokin.in> wrote:
Hi Shrinivas,
Wouldn’t these just be variables?
Cond1 = color == Blue and count == 20 Cond2 = color == Red
if cond1 or cond2: Do something elif cond3: Do something else
Regards Rajeev J Sebastian On 8 Mar 2020, 20:42 +0530, Shrinivas Kulkarni <shrinivk@gmail.com>,
wrote:
Hello Everyone
While writing python code, I frequently come across the need to do certain tasks based on combined conditions.
Much of the task for all the sub-conditions are common but some are specific to one or more of these sub-conditions.
A simplified example:
########################## Code ########################## if (color == BLUE and count == 20) or (color == RED and count % 5 == 0): rotate_the_wheel() # Common to the two sub-conditions if(color == BLUE and count == 20): # First sub-condition set_signal() if(color == RED and count % 5 == 0): # Second sub-condition clear_signal() proc_post_rotate() # Common to the two sub-conditions
I am not sure if there is a better way to do this. If not, maybe there can be an extension to the language, which would allow marking a sub-condition just like we mark a sub-expression in a regular expression.
Tentative syntax for this could be ({} marks the sub-condition and \number refers back to it):
########################## Code ########################## if {(color == BLUE and count == 20)} or {(color == RED and count % 5 ==
0)}:
rotate_the_wheel() if(\1): # First marked condition set_signal() if(\2): # Second marked condition unset_signal() proc_post_rotate()
And like sub-expressions, the nesting of marked sub-condions should also be possible:
########################## Code ########################## if {{(color == BLUE and count == 20)} and {value == 20}} or {(color == RED and count % 5 == 0)}: if(\1):# Refers to the entire subcondition {{(color == BLUE and count == 20)} and {value = 20}} proc1() if(\2):# Refers to sub-subcondition {value == 20}
This will not only avoid the repetition of sub-conditions, but make code readable since something like \1 will give an immediate indication of a sub-condition that's defined earlier.
Please let me know something similar is already implemented. Even otherwise, all your thoughts, inputs and criticism are welcome.
Thanks and best regards Shrinivas Kulkarni _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-leave@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/M5OUL4... Code of Conduct: http://python.org/psf/codeofconduct/
Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-leave@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/7I3K72... Code of Conduct: http://python.org/psf/codeofconduct/
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Shrinivas Kulkarni