how to format long if conditions

Colin J. Williams cjw at ncf.ca
Sat Aug 27 23:25:10 CEST 2011


On 27-Aug-11 11:53 AM, Hans Mulder wrote:
> On 27/08/11 17:16:51, Colin J. Williams wrote:
>
>> What about:
>> cond= isinstance(left, PyCompare)
>> and isinstance(right, PyCompare)
>> and left.complist[-1] is right.complist[0]
>> py_and= PyCompare(left.complist + right.complist[1:])if cond
>> else: py_and = PyBooleanAnd(left, right)
>> Colin W.
>
> That's a syntax error. You need to add parenthesis.
>
> How about:
>
> cond = (
> isinstance(left, PyCompare)
> and isinstance(right, PyCompare)
> and left.complist[-1] is right.complist[0]
> }
> py_and = (
> PyCompare(left.complist + right.complist[1:])
> if cond
> else PyBooleanAnd(left, right)
> )
>
> -- HansM

I like your 11:53 message but suggest indenting the if cond as below to 
make it clearer that it, with the preceding line, is all one statement.

Colin W.

#!/usr/bin/env python
z= 1
class PyCompare:
     complist = [True, False]
     def __init__(self):
         pass
left= PyCompare
right= PyCompare
def isinstance(a, b):
     return True
def PyBooleanAnd(a, b):
     return True
def PyCompare(a):
     return False
z=2

def try1():

       '''    Hans Mulder suggestion  03:50  '''
       if (
           isinstance(left, PyCompare)
           and isinstance(right, PyCompare)
           and left.complist[-1] is right.complist[0]
       ):
           py_and = PyCompare(left.complist + right.complist[1:])
       else:
           py_and = PyBooleanAnd(left, right)

def try2():
       '''        cjw response - corrected  11:56  '''
       cond=  (isinstance(left, PyCompare)
              and isinstance(right, PyCompare)
              and left.complist[-1] is right.complist[0])
       py_and= (PyCompare(left.complist + right.complist[1:]) if cond
               else PyBooleanAnd(left, right))

def try3():
     '''       Hans Mulder 11:53   '''
     cond = (
         isinstance(left, PyCompare)
         and isinstance(right, PyCompare)
         and left.complist[-1] is right.complist[0]
         )  # not }
     py_and = (
              PyCompare(left.complist + right.complist[1:])
              if   cond
              else PyBooleanAnd(left, right)
             )
def main():
     try1()
     try2()
     try3()
if __name__ == '__main__':
     main()
     pass




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