[Python-ideas] Making colons optional?

[Lie Ryan]

On Tue, 10 Feb 2009 10:54:52 -0600, Ron Adam wrote:

> Lie Ryan wrote:
>> On Thu, 05 Feb 2009 12:07:39 -0500, Scott Dial wrote:
> 
>> personally, I like this:
>> 
>> if some() and some_other() or \
>>    some_more(complex=(True,)) and \
>>    a_final_call(egg=(1,2,3)) \
>>     :
>>     do_something()
> 
> 
> My preference is to lead with keywords or symbols when it's convenient:
> 
> if (some()
>          and some_other()
>          or some_more(complex=(True,))
>          and a_final_call(egg=(1, 2, 3))):
>      do_something()
> 
> 
> For long math expressions spanning multiple lines I usually split before
> addition or subtraction signs.
> 
> if (some_long_value * another_long_value
>           + some_long_value * a_special_quanity -
>           an_offset_of_some_size):
>      do_something()
> 
> 
> With syntax highlighting these becomes even more readable.  The eye and
> mind just follow along the vertical line of highlighted keywords or
> operations until it reaches the end.
> 
> As far as optional things go, I'd like the '\' to be optional for
> multiple lines that end with a ':'.  Adding parentheses around the
> expression works, but it seems like a compromise to me.
> 
> Cheers,
>      Ron

Under ideal circumstances, when I see codes like that I'll turn it into a 
function. Such a complex expression decreases readability exponentially, 
turning it into a function would make it much more readable. Worse is if 
the expression uses a lot of parentheses, it becomes a nightmare trying 
to count the parentheses, keep it balanced, and keep it logically correct.

r = 1.0 / (
          (n**p * p**n)**(n*p) + 
          l**w
    )

where
r = readability
n = number of terms
p = number of parentheses used to change evaluation order
l = number of lines
w = average width of each line

n = 4, l = 4, p = 3, w = 20
the readability of that expression is:

r = 2.6547283374476086e-45