3 added 74 characters in body edited Jul 19 '15 at 12:24 ctrl-alt-delor 56144 silver badges99 bronze badges Say it once and only once: in `x = x + 1`, I say 'x' twice. But do not ever write, 'a = b +=1' or we will have to kill 10 kittens, 27 mice, a dog and a hamster.   Some people argue that youYou should never change the value of a variable, as it makes it easier to prove the code is correct — see functional programming. However if you do, then it is better no say things only once. Say it once and only once: in `x = x + 1`, I say 'x' twice. But do not ever write, 'a = b +=1' or we will have to kill 10 kittens, 27 mice, a dog and a hamster. Some people argue that you should never change the value of a variable, as it makes it easier to prove the code is correct. Say it once and only once: in `x = x + 1`, I say 'x' twice. But do not ever write, 'a = b +=1' or we will have to kill 10 kittens, 27 mice, a dog and a hamster.   You should never change the value of a variable, as it makes it easier to prove the code is correct — see functional programming. However if you do, then it is better no say things only once. 2 added 2 characters in body edited Feb 9 '12 at 22:28 Peter Mortensen 1,08122 gold badges1111 silver badges1414 bronze badges Say it once and only once: in `x = x + 1`, I say 'x' twice. But do not ever write, 'a = b +=1' or we will have to willkill 10 kittens, 27 mice, a dog and a hamster. Some people argue that you should never change the value of a variable, as it makes it easier to prove the code is correct.   Say it once and only once: in `x = x + 1` I say 'x' twice But do not ever write, 'a = b +=1' or we will have to will 10 kittens, 27 mice, a dog and a hamster. Some people argue that you should never change the value of a variable, as it makes it easier to prove the code is correct.   Say it once and only once: in `x = x + 1`, I say 'x' twice. But do not ever write, 'a = b +=1' or we will have to kill 10 kittens, 27 mice, a dog and a hamster. Some people argue that you should never change the value of a variable, as it makes it easier to prove the code is correct. 1 answered Feb 9 '12 at 14:28 ctrl-alt-delor 56144 silver badges99 bronze badges Say it once and only once: in `x = x + 1` I say 'x' twice But do not ever write, 'a = b +=1' or we will have to will 10 kittens, 27 mice, a dog and a hamster. Some people argue that you should never change the value of a variable, as it makes it easier to prove the code is correct. Post Made Community Wiki by ctrl-alt-delor occurred Feb 9 '12 at 14:28