`--(...==...)--(...==...)` 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.
'%c' * (length_of_string_to_format) % (number, number, ..., length_of_string_to_format_numbers_later)
is the expression being evaluated here after you collapse all of the 1s + math formatting each number in the tuple as a unicode char for each '%c' escape in the string corresponding to its place in the tuple.
[1] https://docs.python.org/3/library/string.html#format-specifi...
print('hello, world')I noticed some ** and * in the thing sent to eval(), which (given that the building blocks are small integers) seemed related to prime factorizations.
The initial %c is duplicated 21 times (3*7, if I read correctly), and then string-interpolated (%c%c%c...) against a long tuple of integers. These integers themselves are composed of products of factors combined using * and **.
There is also one tuple "multiplication" embedded within that long tuple of integers -- (a,b)*2 = (a,b,a,b). That is for the 'l' 'l' in "hello".
It's all very clever and amusingly mathy, with a winking allusion to the construction of natural numbers using sets. It made me Godel.
For example if you make this class:
class _:
def __neg__(self):
return -1
def __sub__(self, other):
return 1-other
>>> --_()
1
>>> _()--_()
2
alert(1)
// equals to:
[][(![]+[])[+!+[]]+(!![]+[])[+[]]][([][(![]+[])[+!+[]]+(!![]+[])[+[]]]+[])[!+[]+!+[]+!+[]]+(!![]+[][(![]+[])[+!+[]]+(!![]+[])[+[]]])[+!+[]+[+[]]]+([][[]]+[])[+!+[]]+(![]+[])[!+[]+!+[]+!+[]]+(!![]+[])[+[]]+(!![]+[])[+!+[]]+([][[]]+[])[+[]]+([][(![]+[])[+!+[]]+(!![]+[])[+[]]]+[])[!+[]+!+[]+!+[]]+(!![]+[])[+[]]+(!![]+[][(![]+[])[+!+[]]+(!![]+[])[+[]]])[+!+[]+[+[]]]+(!![]+[])[+!+[]]]((![]+[])[+!+[]]+(![]+[])[!+[]+!+[]]+(!![]+[])[!+[]+!+[]+!+[]]+(!![]+[])[+!+[]]+(!![]+[])[+[]]+([][(![]+[])[+!+[]]+(!![]+[])[+[]]]+[])[+!+[]+[+!+[]]]+[+!+[]]+([]+[]+[][(![]+[])[+!+[]]+(!![]+[])[+[]]])[+!+[]+[!+[]+!+[]]])()
>>> 0^((...==...)--++--(...==...))^0
2Except for package management, of course. There, we need lots and lots of ways.
benob•1y ago
seplox•1y ago
qsort•1y ago
Python doesn't have "--", which allows the tokenizer to do something else.
nyrikki•1y ago
I am pretty sure the decriment operator came around well after that quirk was established.
seanhunter•1y ago
j2kun•1y ago