“You already have to.” –> If something is bad, don't change it? (1) Block expressions are not useful because you can't use them as expressions (=retreive their value) if you don't use “string eval”. (2) Object syntax is restricted because lookahead comes at a cost for parsers.
This is a mess. Beginners hate it. Parsers don't like it. And yet it's still
there...
Personnaly, I would like to do something like that (and I remind an earlier
proposal from the mailing list) :
// try to create an "x" variable
let x = try { doSomething() } catch (ex) {};
or
// log the value of 1+2+3+...+10
console.log (eval { let i=10, j=0; while(i) { j+=i—; } });
Now, I have to do something like that :
// not as readable
let x; try { x=doSomething() } catch (ex) {}
or
// bad but close in term of input
console.log(eval("let i=10, j=0; while(i) { j+=i--; }"));
// as optimized, but not as readable
{ let i=10; let j=0; while(i) { j+=i--; }; console.log(j); };
The introduction of the “eval” keyword before a block has tons of other
advantages :
{}.toString(); // will now compile and return “[object Object]” from
anywhere in the code
That means I can do something like :
let props = eval {
let obj = func();
let prop1 = getProp1(obj);
let prop2 = getProp2(obj, prop1);
{
prop1: prop1,
prop2: prop2
}
}
Another proposed syntax, namely
this.function() {} <—> (function() {}).bind(this)
will now be acceptable since
function() {
return this.function(); //ASI
{
doSomething();
}
}
is not allowed in ES6, there’s no syntax conflict. So, we can introduce the
[noLineBreak] token after “function” safely.
BTW, I also think we should drop labels for ES6. This will help to simplify
syntax, too. With ES6, we should build a new syntax that’s more logical to use.
-----Message d'origine-----
From: Mike Samuel
Sent: Wednesday, January 04, 2012 9:17 PM
To: Herby Vojčík
Cc: François REMY ; [email protected]
Subject: Re: Boolean shortcuts
2012/1/4 Herby Vojčík <[email protected]>:
> Hi,
>
> If you must think whether you should put it in
> parentheses or not to prevent runtime error, you rather write { window:false
> } and reduce the insecurity.
You already have to.
'boolean' === typeof eval('{ window: false }')
See section 12.4 : http://es5.github.com/#x12.4
"""
12.4 Expression Statement # Ⓣ
Syntax
ExpressionStatement :
[lookahead ∉ {{, function}] Expression ;
NOTE An ExpressionStatement cannot start with an opening curly brace
because that might make it ambiguous with a Block.
"""<<wlEmoticon-smile[1].png>>
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