but then, I've had my share of turrible bugs too, so i'm not here to poke fun.
Downvoters: most programming languages don’t silently convert strings (i.e., usernames) to array indices. Even Python doesn’t do this. While this particular bug probably wouldn’t be possible in most other languages, I’m only commenting because it’s rare and amusing to see bugs that are so language specific. I’m not making a generic “lol PHP” joke.
And it's certainly possible in Python to accidentally use a map as a list or vice versa, if the map has integer keys.
var arr = ["one", "two", "three"];
arr["2"] === "three"; // true> Arrays cannot use strings as element indexes (as in an associative array) but must use integers. Setting or accessing via non-integers using bracket notation (or dot notation) will not set or retrieve an element from the array list itself, but will set or access a variable associated with that array's object property collection. The array's object properties and list of array elements are separate, and the array's traversal and mutation operations cannot be applied to these named properties.
First sentence, “An array in PHP is actually an ordered map.”
† btw, have you seen this? https://stackoverflow.com/questions/2473989/list-of-big-o-fo... pretty detailed investigation of big-O for PHP arrays
class Foo:
def __getitem__(self, x):
return x
i = iter(Foo())
print(next(i))
print(next(i))
But interfaces are just one way to declare a type. The question is, did it convert it to a new type?
Well, what type was it before? If you want to talk about LSP[0], you're a bit stuck here since you can't prove anything about a method in python. (And here, we declared its type, and we said nothing about it being iterable or a sequence.) You have to run it because you don't know that a. Foo has __iter__ or __getitem__, b. that they accept the arguments you're going to pass, c. let alone that they're designed to, d. that the object won't simply delete them halfway through.
All that iter() is going to do is look for those methods and make assumptions that if you wrote __getitem__ that you meant it. At which point maybe LSP works, after all, you'll prove that it has that property by running the code and fixing it if it breaks.
But... python nevertheless will nevertheless construct this proxy to use your class based on inspection, which seems an awful lot like coercion to me.
[0]: Quoth Wikipedia: Let 𝜙(𝑥) be a property provable about objects 𝑥 of type T. Then 𝜙(𝑦) should be true for objects 𝑦 of type S where S is a subtype of T.
>>> b'egg' + u'spam'
u'eggspam'
>>> True + 1
2 fizzbuzz = lambda n: [print((“fizz” * m % 3 == 0) + (“buzz” * m % 5 == 0) or m) for m in range(n)]