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CoffeeScript's approach toward top-level variables is quite elegant and simple. When you declare a variable at top-level scope, it is equally available to all

CoffeeScript's approach toward top-level variables is quite elegant and simple. When you declare a variable at top-level scope, it is equally available to all code within that file for both reading and writing, with no strange "nonlocal" or ":=" syntax to complicate manners. Once you understand the reach of CoffeeScript's top-level variables, it is easy to write bug-free code. Since you know that top-level variables have wide scope, you simply need to be judicious about putting variables at top-level scope. If a variable is not needed at top level scope, don't put it there.

the_mitsuhiko 15y ago
Way to miss the issue. I was not suggesting ":=" for global variables at all. I was suggesting ":=" as a replacement for the nonlocal keyword that Python 3 has to solve the issue I was demonstrating.
- showell30 15y ago
  Nope, I get it, you were suggesting ":=" as a replacement for the "nonlocal" keyword in Python. I'm not sure how my comments demonstrate any lack of reading comprehension. All I said about ":=" and "nonlocal" is that they are overly complicated once you accept that top-level variables can have wide scope. Obviously, plenty of folks managed to write bug-free code in Python before "nonlocal" was invented. I'm not saying it's a bad idea, but you can avoid bugs without it.
  - the_mitsuhiko 15y ago
    > Obviously, plenty of folks managed to write bug-free code in Python before "nonlocal" was invented. Python has the inverse behavior of CoffeeScript. So that was never an issue.
    - showell30 15y ago
      Well, fine, but Python2 had the inverse problem--you couldn't mutate top-level variables without awkward "global" statements.
      - notSorella 15y ago
        That's a whole different matter, which can't make you shoot yourself in the foot without knowing it for any non-trivial code. CoffeeScript's scoping forces you to always keep track of whatever is enclosing the current scope ALL THE WAY TO THE TOP. This is way too much when your function doesn't need to access outer variables (which should be the minority of the cases). So, problem is, you either make all your functions have non-free variables (but Jashkenas seems to dislike functions shadowing outer variables too, which is just... overtly weird), or you keep track of all variables above the current scope. The former is not too unreasonable, until you remember it makes no sense with closures :3
        showell30 15y ago
        You are correct that variable scoping goes all the way to the top, but nobody is forcing you to create top-level variables with overloaded names like "log". Seriously, if you have a file that uses log files and logarithms, just take some care to distinguish the concepts. Use "log_file" for log files; use "logarithm" or "Math.log" for inverse exponentation.
        xnxn 15y ago
        > Use "log_file" for log files; use "logarithm" or "Math.log" for inverse exponentation. Just clarifying; are you actually suggesting this, or was that sarcasm?
        showell30 15y ago
        It's a serious suggestion. Instead of introducing four top-level variables (log, sin, cos, and tan), just introduce one (Math) that wouldn't possibly conflict with a local.

the_mitsuhiko 15y ago

Way to miss the issue. I was not suggesting ":=" for global variables at all. I was suggesting ":=" as a replacement for the nonlocal keyword that Python 3 has to solve the issue I was demonstrating.

showell30 15y ago
Nope, I get it, you were suggesting ":=" as a replacement for the "nonlocal" keyword in Python. I'm not sure how my comments demonstrate any lack of reading comprehension. All I said about ":=" and "nonlocal" is that they are overly complicated once you accept that top-level variables can have wide scope. Obviously, plenty of folks managed to write bug-free code in Python before "nonlocal" was invented. I'm not saying it's a bad idea, but you can avoid bugs without it.
- the_mitsuhiko 15y ago
  > Obviously, plenty of folks managed to write bug-free code in Python before "nonlocal" was invented. Python has the inverse behavior of CoffeeScript. So that was never an issue.
  - showell30 15y ago
    Well, fine, but Python2 had the inverse problem--you couldn't mutate top-level variables without awkward "global" statements.
    - notSorella 15y ago
      That's a whole different matter, which can't make you shoot yourself in the foot without knowing it for any non-trivial code. CoffeeScript's scoping forces you to always keep track of whatever is enclosing the current scope ALL THE WAY TO THE TOP. This is way too much when your function doesn't need to access outer variables (which should be the minority of the cases). So, problem is, you either make all your functions have non-free variables (but Jashkenas seems to dislike functions shadowing outer variables too, which is just... overtly weird), or you keep track of all variables above the current scope. The former is not too unreasonable, until you remember it makes no sense with closures :3
      - showell30 15y ago
        You are correct that variable scoping goes all the way to the top, but nobody is forcing you to create top-level variables with overloaded names like "log". Seriously, if you have a file that uses log files and logarithms, just take some care to distinguish the concepts. Use "log_file" for log files; use "logarithm" or "Math.log" for inverse exponentation.
        xnxn 15y ago
        > Use "log_file" for log files; use "logarithm" or "Math.log" for inverse exponentation. Just clarifying; are you actually suggesting this, or was that sarcasm?
        showell30 15y ago
        It's a serious suggestion. Instead of introducing four top-level variables (log, sin, cos, and tan), just introduce one (Math) that wouldn't possibly conflict with a local.