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Comment by Eliezer | Hacker News Reader

Call me loony but I see nothing surprising here. It's just indirection... I guess I've probably got some Elder Thing blood in me.

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For what it's worth, I used variable variables when making a DB class for a project I was working on last year.

It isn't something you can easily debug and it is complicated. That said, it isn't the gates to hell that it is represented as. It's a tool, and it can make code cleaner if you want it to.

function __tostring(){ $items = ['title','header','comment'] foreach($items as $item){ echo $this->$item; } }

Make that list of class variables much longer and you start to see the benefits in certain cases.

There are times when I do miss variable variables.

Python has it in a more object-oriented way ...

    def print_string(self):
        items = ['title', 'header', 'comment']
        for item in items:
            print getattr(self, item)

Where "getattr" is just a pretty protocol for calling ...

    self.__dict__[item]

This extends to whatever you want, including members of namespaces (like declared classes, functions, other namespaces, etc...)

There is actually a little more to getattr in that __dict__ just has attributes local to that instance where as getattr (also instance.attribute syntax) also accesses class attributes, non-bound methods, and properties. Additionally, these non-local attributes can also be inherited from parent classes.

I laughed at TFA, largely because it's clever and lucidly written, and cringed at the thought of what sorts of horror an unskilled operator could inflict with this on the poor dumb bastards charged with maintenance; but I'd rather my language err on the side of lunacy.

The loony thing is that the indirection is by name, not by reference, which allows the indirection to be a lot less predictable. Compared to pointers, it's like the data structure equivalent of using dynamic scope instead of lexical scope.

Indeed, call me when you're using complicated string-returning lambda functions inside the brackets and maybe then I'll--well, probably just redirect you to an obfuscated PHP contest, but cheers.

It's not even really indirection. Variable variables using strings is a useful feature for quickly getting functionality up and running (although there are usually security trade-offs, especially if you accept user input as the string to be evaluated).

Edited for clarity

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