You need (need in the sense "having readable construct to perform")
.{...} with [[DefineOwnProperty]] not for "foo":"bar" (yes, there
[[Put]] should happen), but for dynamically adding concise methods
and/or getters/setters to objects.
Using API is much more cumbersome here. And lots of bugs can appear if
people will use .defineProperties instead of .defineMethod, for example.
And object literal extension, because it has identical syntax, is super
readable.
Not that I don't like the idea, by the way... but stopping literal
extension is too much. Retain it in some way (like foo.={literal} or so).
Herby
David Herman wrote:
On May 29, 2012, at 9:33 AM, Tab Atkins Jr. wrote:
Same thoughts here. Regular devs (like me!) only see
[[DefineOwnProperty]] when creating a literal, and then there's no
observable distinction between these two in normal circumstances:
Bingo. The different between [[DefineOwnProperty]] and [[Put]] is subtle and
rarely encountered when dealing with a new object.
The distinction between the two operations is a corner case of the language,
and [[Put]] is the common case.
I don't think it's worth optimizing for the [[DefineOwnProperty]]
case. We should just use the standard "foo:bar" syntax, and have it
invoke [[Put]] behavior.
I agree we should only be considering syntax for [[Put]] -- syntactic sugar
should be to support common patterns, not to invent patterns that don't fit
smoothly within the rest of the language.
However, I really, really oppose reusing syntax that's used for declarative
data construction (i.e., literals) to notate *update* operations. We should not
use the object literal notation for [[Put]]. We should use assignment syntax,
which corresponds to doing assignment on an object.
This was the motivation between my blog post a while back on a different syntax
for mustache:
http://blog.mozilla.org/dherman/2011/12/01/now-thats-a-nice-stache/
tl;dr: instead of an object literal, the RHS of mustache should have a syntax
that corresponds more closely to that of blocks. It allows assignments and
method calls.
array.{
pop();
pop();
pop();
};
path.{
moveTo(10, 10);
stroke("red");
fill("blue");
ellipse(50, 50);
};
this.{
foo = 17;
bar = "hello";
baz = true;
};
(I'll eventually write up a new strawman for it, but I'm working on the new
wiki right now which I consider higher priority.)
Dave
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