[Qt-qml] Semantics of 'return' in a JavaScript block in QML

[Pertti Kellomäki]

On 09/29/2010 01:50 PM, ext Stephen Kelly wrote:
> Pertti Kellomäki wrote:
>
>    
>> On 09/16/2010 03:37 AM, Kennedy Aaron (Nokia-MS-Qt/Brisbane) wrote:
>>      
>>> Internally
>>> the above is actually evaluated like this:
>>>
>>> Text {
>>>       text: (function() { if (condition) { return "A"; } return "B"; })()
>>> }
>>>
>>>        
>> This would actually be a good way to document it, at least to a former
>> Lisp-head like myself ;-)
>>      
>
> As a C++ head I rarely see syntax like the above and I find it quite
> difficult to parse.
Me too. It would be a lot clearer as

    (lambda () (if condition "A" "B"))()

;-)

>   I've seen stuff like that when reading jQuery.js and
> code that uses it, but what is actually happening and why is it such a
> common construct when using javascript? Got links?
>
> It looks like a unnamed function is defined 'inline' inside some (), like a
> python lambda function or so, and then called immediately. Is that what's
> happening?
>    
AFAIK that is exactly what is going on, though I have to say I am also a 
bit puzzled by the need of parenthesis around the anonymous function.
-- 
Pertti