Side-effects of some Array methods ...

Brendan Eich brendan at
Fri Jun 27 15:57:46 PDT 2008

On Jun 27, 2008, at 3:45 PM, Garrett Smith wrote:

> to list ->

I am not the one replying to sender only -- all of my replies to you  
have cc'ed the list. You have replied twice to me only, then resent  
as reply-alls. What mailer are you using?

>> Again, we don't know what failing faster (you mean throwing a new  
>> error as
>> an exception) would break. The shell session above shows how fail- 
>> soft could
>> leave scripts executing and even behaving well. Throwing an  
>> exception that's
>> not caught would rain on such scripts' parades.
> I hardly call that a parade. It looks like a toy program aimed at

My shell example is not the "parades" plural referenced above, merely  
a demo of fail-soft behavior. The unknown web scripts that might  
depend on that behavior could be doing useful work based on the  
current semantics ("having parades").

> How do you address these concern? Is it better to fail fast or fail
> later? If later, and in the case or attempting to set a ReadOnly
> property, then should the failure be silent? (String example). What
> about the NodeList example?

This is not a green-field design exercise. My point is that browsers  
do what ES1-3 said (depending on the Array method; generics were  
there all along, but some were added IIRC after ES1). Code tends to  
depend on detailed semantics (not always, but more often than you'd  
think). Why rock the boat?


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