In what ways does the following "eval" regularity break?

Brendan Eich brendan at mozilla.com
Thu Oct 30 00:18:43 PDT 2008


On Oct 29, 2008, at 11:46 PM, Maciej Stachowiak wrote:

> Personally I think use of the local-scope eval should be  
> discouraged. We should introduce an explicit globalEval function  
> which has eval function rather than eval operator semantics, i.e.  
> evaluates at global scope. In my experience, programs using eval  
> rarely truly want local eval,

SunSpider has some evals that absolutely want their caller's scope.

> and so they are doing something that defeats lexecial analysis for  
> no reason.

There are lots of dumb eval uses, but I do not agree that most eval  
calls could be global-eval. The EXT Ajax library among many others  
uses local eval to compile optimized selector-matching functions, e.g.  
IIRC gmail uses local eval (and global).

> I think we should even consider banning local eval from strict mode.

In light of the examples I gave above, and more that are pretty easy  
to find, I think this would make strict mode unused in practice.

/be


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