Pylint false positives

[Gregory Ewing]

Marko Rauhamaa wrote:
> Chris Angelico <rosuav at gmail.com>:
> 
>>3) Every invocation of method() has to execute the class body, which
>>takes time.
> 
> That's what happens with every method invocation in Python regardless.

No, it doesn't! Invoking a method involves creating a bound method
object, which is very small and lightweight. Executing a class
statement creates a class object, which is enormous by comparison,
and quite expensive to initialise.

A quick test of your Outer class vs. Chris Angelico's version
suggests that yours is about 12 times slower at creating instances
of Inner.

from timeit import timeit

class Outer1:

     def method(self):
         outer = self
         class Inner:
             def spam(self, a, b):
                 outer.quarantine(a, b)
         return Inner()

     def quarantine(self, a, b):
         pass


def test1():
     x = Outer1()
     for i in range(100000):
         y = x.method()
         y.spam(1, 2)


class Outer2:

     class Inner:

         def __init__(self, outer):
             self.outer = outer

         def spam(self, a, b):
             self.outer.quarantine(a, b)

     def method(self):
         return self.Inner(self)

     def quarantine(self, a, b):
         pass


def test2():
     x = Outer2()
     for i in range(100000):
         y = x.method()
         y.spam(1, 2)


t1 = timeit(test1, number = 1)
print("Nested class:    ", t1)

t2 = timeit(test2, number = 1)
print("Non-nested class:", t2)

print("Ratio =", t1 / t2)

----------------------------------------------
Results:
----------------------------------------------
Nested class:     1.899524817999918
Non-nested class: 0.15806536600030086
Ratio = 12.01733729573816

-- 
Greg