I'd argue that the things that are wrong with "dynamic scope"
in the Lisp sense (usage #1) are just as wrong with "non-static
scope" (usage #2). Dynamic scope in Lisp was anti-modular
because the meaning of a variable could be affected by any
code throughout the arbitrary control flow of the program.
The same is true whenever you have variables whose bindings
are decided by dynamic control flow. Lisp's dynamic binding
was just a special case of the general phenomenon of variables
whose bindings are determined dynamically. This is why, in
my mind, the distinction isn't actually all that important.
Perhaps the example below helps: it contrives to emulate
dynamic scoping by dynamic (global) binding, complete
with emulating local, stack-backed bindings, using temporary
(global) bindings plus static stack.
Claus
function log(msg) {
if (typeof console!=='undefined')
console.log(msg);
else if (typeof WScript!=='undefined')
WScript.Stdout.WriteLine(msg);
}
function B(l) {
log(l+': x is '+x);
// x is always global, but may not exist there;
//
// that still isn't static scoping; it is "just"
// a question of whether x is bound, not where
// it is bound, but the answer is not static.
//
// (if x isn't there, that is a reference error,
// not an undefined)
}
if (Math.random()>0.5)
this.x = "hi"; // now you see it, now you don't
// dynamic binding with global scope
if (typeof x=="undefined") {
this.x = "ho";
B("local"); // emulate dynamic scoping by dynamic binding
delete this.x;
} else { // x is defined
B("global");
(function(){
var old_x = x; // use lexical stack to backup x
delete x; // shadow x
try { B("gone 1"); } catch(e) { log('x no longer defined'); }
x = "temporary"; // emulate a local binding by
// a temporary global binding
B("dynamic"); // dynamic scoping, in all but name
delete x; // local/temporary binding ends
try { B("gone 2"); } catch(e) { log('x still not defined'); }
x = old_x; // restore x
}());
}
B("main");
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