I think that what he meant is that we know for sure in which scope we can find
the property/variable. That the propery exists or not in the that scope is
another issue.
So, in the code “function getOoops(t) { t(); return function() { return ooops;
} }” we know statically that the scope where the “ooops” variable is defined is
the global scope. At runtime, we just need to do “globalScope.get(‘oops’)" to
retreive the value (or throw). In non-strict ES, the “t” function may be eval,
and eval could add a “oops” variable in the parent function getOoops. So, we
don’t know at compilation if “ooops” belong the the global scope of from the
function’s scope (we can only find that out at runtime).
From: Šime Vidas
Sent: Wednesday, October 03, 2012 6:41 PM
To: es-discuss@mozilla.org
Subject: Is ES5 Strict a fully statically scoped language?
In the talk "Changes to JavaScript, Part 1: EcmaScript 5", Mark Miller states
that ES5 Default contains four static scope violations (direct link:
http://www.youtube.com/watch?v=Kq4FpMe6cRs&t=42m53s). He also states that ES5
Strict corrects these violations, making ES5 Strict is a statically scoped
language. I don't understand how that can be true, since it is possible to
dynamically add bindings to the global environment by creating new global
properties (during code evaluation). Isn't this a static scope violation, too?
-- Šime Vidas
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