Comment by horsawlarway | Hacker News Reader

Comment by horsawlarway | Hacker News Reader

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Way late, but your response sort of proves the point. You're having to argue about what I can infer about the language.

What JS/Ruby/Lisp/Perl/Java do is irrelevant. Hey, C/Go/D/C++ would all be more likely to append by value, but neither of us care a whit because it's asking about Python, which I know nothing about.

So (and this is really hard) try to forget that you've got experience with the language, and approach it as a random pseudo language: this question has no clear answer, because it depends on the memorized implementation details of the standard library of a language...

That's bad.

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Finally: JS doesn't have matrix as a base type (boolean/number/string/null/undefined/symbol is it, baby), so for this same question, I'd strongly argue that you're simply wrong about bucketing JS with those other languages. Again, for JS the question would revolve around the implementation details of the matrix object and its prototype. Trust me, I can write a useful matrix implementation that appends by value in JS.

> What JS/Ruby/Lisp/Perl/Java do is irrelevant. Hey, C/Go/D/C++ would all be more likely to append by value, but neither of us care a whit because it's asking about Python, which I know nothing about.

I guess my point was that you should be able to infer that Python would be more likely to behave like JS/Ruby/Lisp/Perl/Java than C/Go/D/C++. If you know or can tell by looking at it that it's much more in the first camp then the second, then you should be able to guess. You're probably right that I overstated how easy that is to tell just from the syntax if you don't know anything at all about Python, but it's also pretty short of memorizing implementation details.

> Finally: JS doesn't have matrix as a base type (boolean/number/string/null/undefined/symbol is it, baby), so for this same question, I'd strongly argue that you're simply wrong about bucketing JS with those other languages. Again, for JS the question would revolve around the implementation details of the matrix object and its prototype.

The 'matrix' in the question wasn't a special matrix type, it was just a list of lists. Word-for-word translated into Javascript it would look like:

    let matrix = []
    let row = [0, 0]
    for (let i = 0; i < 2; ++i) matrix.push(row)
    matrix[1][1] = 1

Question: If you were given a new block of code below, what is the result of X if X is passed by reference?

[Block of code]

     1. 34
     2. 17
     3. 43
     4. 22.5
     5. Not listed

____________________

This would be a much more clearer way of handling pass by ref/value. 2 of the answers are correct, so this could be reused to ask the other one. If they're being tricky, they can award half-credit for choosing the wrong pass-by-*. And 3 other answers are junk. And this abstracts out any sort of programming neologims or fetishization of $random_language.

But that LITERALLY is memorizing implementation details.

Here are the rules for JS, which I happen to know, because I use it often:

1. Javascript is always pass by value, but when a variable refers to an object (including arrays), the "value" is a reference to the object.

2. Changing the value of a variable never changes the underlying primitive or object, it just points the variable to a new primitive or object.

3. Changing a property of an object referenced by a variable does change the underlying object.

Those are not trivial "just infer it" details. That's highly language specific, and absolutely unrelated to the skills the test claims to be evaluating.

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