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And this is why I tend to use a slightly smaller subset of some of the features that C-family languages support, along with an abundance of brackets.

If I remember rightly, there is the example:

    a = {-1, -1}
    x = 0
    a[++x] = x
    print(a[0] + " " + a[1])

Depending on the language (and sometimes even if you have optimizations set for those that compile to binaries), you'll get a different answer.

I always love (read sarcasm) to see awesome code, such as:

    z = a & b > c | d

or:

    z = a > b ? c < d ? e : f : g ? h : i

And then of course, the statement: "my code doesn't need comments because the code comments itself"...

Don't do that. The behavior is explicitly undefined in C. http://c-faq.com/expr/seqpoints.html

Don't do what, precisely? He listed several examples.

And I think he's agreeing with you, he's just sarcastic.

He said, "this is why I tend to use a slightly smaller subset of some of the features that C-family languages support, along with an abundance of brackets."

C does not support his first example. The standard states that the behavior is undefined.

> If I remember rightly [..]

You're probably not wrong, but I specifically remember there was something you could do in order to trick the compiler to allow modification on the left hand side to happen. It could possibly be by having two variable names referencing the same variable - for example.

Besides, the whole point was that it's usually not clever "trying to be clever". It just creates confusion. I don't personally believe the majority of people need to test the entire C spec to it's absolute boundary. A subset serves most people perfectly well.

I've recently started working on a code base with great comments and they are worth their weight in gold. Especially class and method level description comments. And doubly especially the class level ones.

Also there is none of the code golf in there that you have just given as an example.

> z = a > b ? c < d ? e : f : g ? h : i

That's stylistically ugly but not hard to predict; at some point I had it beaten into my head that ternaries are always at the bottom of the single-character operator precedence stack (I really hope all languages stick to that). I'd expect most people to know this.

> z = a & b > c | d

That is harder to predict. I wouldn't expect most people to know this one without looking up a precedence list.

It gets better when you compile that C code as C++, as ?: has a different precedence level.

RHS seems right to me because it means the actions on the LHS happen consecutively.

To expand your example a bit:

  class ShoutyContainer:
      def __setitem__(self, index, value):
          print("Assignment")
  
  def lhs(): print("LHS")
  def rhs(): print("RHS")
  a = ShoutyContainer()
  a[lhs()] = rhs()

Yields:

  RHS
  LHS
  Assignment

If LHS were evaluated first, then it would be separated from the final assignment step by the RHS evaluation. That would be odd.

I think it depends on how you think about it. As mentioned elsewhere, "=" is a special statement syntax rather than an operator in Python, but if you were to think of it like an operator, it would be evaluated in three phases: (1) evaluate one side, (2) evaluate the other side, (3) perform operation. The __setitem__ method defines how the left side participates in step 3, but IMO there's a separate LHS evaluation step that's independent of the assignment itself.

You might call this code snippet analogous:

    class ShoutyNumber:
        def __init__(self, n):
            self.n = n
            print(f'Created {self.n}')
    
        def __add__(self, other):
            print(f'Added with {self.n}')
            return self.n + other.n
    
    ShoutyNumber(1) + ShoutyNumber(2)

Yields:

    Created 1
    Created 2
    Added with 1

But I understand that in some mental models and some implementations, it's cleaner to have the entire RHS value ready before starting any evaluation of the LHS. I think that avoids the need to have "assignable reference" as a special type of expression result.

In Python `=` is not just a binary operator. Python is evaluated left-to-right (but not on assignment).

Is there no language in which evaluation order is random/undefined?

Scheme doesn't define an evaluation order.

As mentioned elsewhere, it's unspecified in C but tends to be right-to-left in practice. To be clear, my categorization of languages is just from testing it directly, I didn't look it up in the spec for any of them. But I think newer languages try to have fully-defined behavior, at least for things like this.