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Message-ID: <7836422.gBDQCprLM3@PointedEars.de>
From: Thomas 'PointedEars' Lahn <PointedEars@web.de>
Reply-To: Thomas 'PointedEars' Lahn <usenet@PointedEars.de>
Organization: PointedEars Software (PES)
Date: Tue, 03 Sep 2013 01:59:17 +0200
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Subject: Re: (golf-ish) Conditional object property access
Newsgroups: comp.lang.javascript
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Ben Bacarisse wrote:

> Thomas 'PointedEars' Lahn <PointedEars@web.de> writes:
>> Ben Bacarisse wrote:
>>> If HAS returns o.p when o.hasOwnProperty('p'), then you can avoid the
>>> conditional
>>> 
>>>   HAS(o, 'p') || <EXPR>
>>
>> Incorrect.  There is a difference between an object having a property and
>> converting the result of a property access to Boolean.  Assuming you
>> meant
>>
>>   function HAS (o, p)
>>   {
>>     if (o.hasOwnProperty(p)) return o[p];
>>   }
>>
>> (where “HAS” is a very unwise identifier), if the value of o[p] was a
>> false- value, the result of
>>
>>   HAS(o, 'p') || <EXPR>
>>
>> would be
>>
>>   <EXPR>
> 
> Yes, good point.  I've used something similar, but in situations where
> this problem would be unlikely.  I was too hasty, though I suppose it's
> possible that || works in all the OP's use cases.

I do not think there is a use-case here.  That is the very nature of code-
golfing, because it is more play than work: trying to find the shortest 
equivalent expression, however unreadable, to solve a *theoretical* problem.  
You would never used golfed code in production: it is probably inefficient, 
likely error-prone, and definitely hard to maintain.
 
>>> Anything that uses functions to wrap EXPR for delayed execution suffers
>>> from the fact the ECMAScript uses such a long keyword, and that the
>>> syntax requires empty parentheses.  (I take it that one of the rules of
>>> this golf game is that the expression should be short.)
>>
>> Harmony (ECMAScript Edition 6) is going to fix that with foo(bar => baz):
>>
>> <http://wiki.ecmascript.org/doku.php?id=harmony:arrow_function_syntax>
> 
> Nice.  The return is no longer needed in simple cases too.  It's always
> seemed to me that the early designers never expected the wide use that
> function expressions would get.

ISTM that this particular syntax for lambda expressions was borrowed from 
C#, which in turn might have shortened that of Python.  I learned it when I 
first used LINQ extension methods about a year ago.

-- 
PointedEars

Twitter: @PointedEars2
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