Maybe ban holes, then... (was: Re: lexical for-in/for-of loose end)

2012-02-02 Thread Herby Vojčík 



Allen Wirfs-Brock wrote:

That said, I'd hate to see things like:

[,x] = someArray;

and even
[a,,y] = someArray;

can be easily missed.

It isn't clear to me that we are doing ES programmers (especially those
with poor eyesight) a favor by allowing such expressions. What is the
evidence with JS1.7 up. How much usage do we see of such holes?


If

  {5:x} = someArray;

and

  {0:a, 2:y} = someArray;

would be possible, there is probably little need for holes. In case of

  [a,b,c,d,,f] = someArray;

one could always use (some conventional) anon-var, like _ (from Prolog):

  [a,b,c,d,_,f] = someArray;

Herby
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Re: Maybe ban holes, then... (was: Re: lexical for-in/for-of loose end)

2012-02-02 Thread Brendan Eich 
This is all unwanted innovation. We have holes in arrays, and in 
SpiderMonkey and Rhino we've had holes in destructuring array patterns 
for years. No one got confused or went blind. We should stop nanny-ing 
about holes.


Some of you don't like holes, but they're not going away in arrays. They 
are useful in array patterns to avoid _ or junk bindings. That's enough 
to keep them, rather than straining to invent more cumbersome ad-hoc 
replacements.


/be


Herby Vojčík mailto:he...@mailbox.sk
February 2, 2012 11:49 AM




If

  {5:x} = someArray;

and

  {0:a, 2:y} = someArray;

would be possible, there is probably little need for holes. In case of

  [a,b,c,d,,f] = someArray;

one could always use (some conventional) anon-var, like _ (from Prolog):

  [a,b,c,d,_,f] = someArray;

Herby
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Re: Maybe ban holes, then... (was: Re: lexical for-in/for-of loose end)

2012-02-02 Thread Herby Vojčík 

Allen Wirfs-Brock wrote:

It isn't just possible, it is already specified as valid. and
youdon't need the quotes around the array indices. But you need a set
ofparams to deal with the expression statement can't start with {
problem. This wouldn't be the case for binding position
destructuring.

({5:x} = someArray);
({0:a, 2:y} = someArray);


A bit off-topic... I don't like paretheses. Not only because I have to 
put them in both ends, but also because of uncomfortable feeling of 
thing closed in parentheses.


Maybe alternative convention to deal with expressions beginning with { 
could be used as well:


  0, {5:x} = someArray;
  0, {0:a, 2:y} = someArray;

Herby
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Re: Maybe ban holes, then... (was: Re: lexical for-in/for-of loose end)

2012-02-02 Thread Andreas Rossberg 
On 2 February 2012 21:19, Brendan Eich bren...@mozilla.org wrote:
 Some of you don't like holes, but they're not going away in arrays. They are
 useful in array patterns to avoid _ or junk bindings. That's enough to keep
 them, rather than straining to invent more cumbersome ad-hoc replacements.

Are you implying that wildcards are more ad-hoc than array holes? That
doesn't add up for me.

/Andreas
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