TIL that in python, 1--2==3

    +a - b; // equivalent to (+a) - b, NOT +(a - b)
    -c + d; // equivalent to (-c) + d, NOT -(c + d)

    +-e; // equivalent to +(-e), the unary + is a no-op if “e” is a built-in type
     // because any possible promotion is performed during negation already

For those who are curious, `...` is a placeholder value in Python called Ellipsis. I don't believe it serves any real purpose other than being a placeholder. But it is an object and it implements `__eq__`, and is considered equal to itself. So `...==...` evaluates to `True`. When you prefix a `True` with `-`, it is interpreted as a prefix negation operator and implicitly converts the `True` to a `1`, so `-(...==...)` is equal to `-1`. Then, you add another prefix `-` to turn the `-1` back into `1`.

`--(...==...)--(...==...)` evaluates to `2` because the first block evaluates to 1, as previously mentioned, and then the next `-` is interpreted as an infix subtraction operator. The second `-(...==...)` evaluates to `-1`, so you get `1 - -1` or `2`.

When chaining multiple together, you can leave off the initial `--`, because booleans will be implicitly converted to integers if inserted into an arithmetic expression, e.g. `True - -1` -> `1 - -1` -> `2`.

> There should be one-- and preferably only one --obvious way to do it.

This article is obviously completely tongue-in-cheek, but I feel the need to point out that this sentence is not meant to be a complete inversion of the Perl philosophy of TIMTOWTDI. The word "obvious" is crucial here - there can be more than one way, but ideally only one of the ways is obvious.

Ok do this but for JavaScript

If you're curious, the code in ellipsis results in executing:

    print('hello, world')

I think we're really starting to over crowd pythons syntax and I'm not a fan.

This behavior can be replicated with any class that has two special methods: __neg__ that returns -1 and __sub__ that accepts ints and returns 1-other.

For example if you make this class:

  class _:
       def __neg__(self):
           return -1
       def __sub__(self, other):
           return 1-other

You get similar behavior:

  >>> --_()
  1
  >>> _()--_()
  2

Fun python for everyone.

You can do this on JavaScript too.

  alert(1)
  // equals to:
  [][(![]+[])[+!+[]]+(!![]+[])[+[]]][([][(![]+[])[+!+[]]+(!![]+[])[+[]]]+[])[!+[]+!+[]+!+[]]+(!![]+[][(![]+[])[+!+[]]+(!![]+[])[+[]]])[+!+[]+[+[]]]+([][[]]+[])[+!+[]]+(![]+[])[!+[]+!+[]+!+[]]+(!![]+[])[+[]]+(!![]+[])[+!+[]]+([][[]]+[])[+[]]+([][(![]+[])[+!+[]]+(!![]+[])[+[]]]+[])[!+[]+!+[]+!+[]]+(!![]+[])[+[]]+(!![]+[][(![]+[])[+!+[]]+(!![]+[])[+[]]])[+!+[]+[+[]]]+(!![]+[])[+!+[]]]((![]+[])[+!+[]]+(![]+[])[!+[]+!+[]]+(!![]+[])[!+[]+!+[]+!+[]]+(!![]+[])[+!+[]]+(!![]+[])[+[]]+([][(![]+[])[+!+[]]+(!![]+[])[+[]]]+[])[+!+[]+[+!+[]]]+[+!+[]]+([]+[]+[][(![]+[])[+!+[]]+(!![]+[])[+[]]])[+!+[]+[!+[]+!+[]]])()

https://jsfuck.com/