Automatic Foreach

[janderson]

Bill Baxter wrote:
> janderson wrote:
>> Bill Baxter wrote:
>>> janderson wrote:
>>>> Bill Baxter wrote:
>>>>> janderson wrote:
>>>>>> What do you think?
>>>>>
>>>>> I think it's already hard enough to figure out what's going to get 
>>>>> called by something like foo(array)
>>>>>
>>>>> It could be
>>>>> - foo(int[] x)
>>>>> - foo(int[] x...)
>>>>> - foo(T)(T x)
>>>>> - foo(T)(T[] x)
>>>>> - foo(T...)(T x)
>>>>> - struct foo { static foo opCall(int[]); }
>>>>> - struct foo { static foo opCall(int[]...); }
>>>>> - struct foo { static foo opCall(T)(T x); }  etc
>>>>> - or struct Foo with non-static opCall on instance foo
>>>>> - or all the same stuff on class  ...
>>>>>
>>>>> So I don't think another meaning for foo(array) is really helpful.
>>>>>
>>>>> I *do* like the idea of an expression (not a statement) that has 
>>>>> foreach-like abilities.  But I think it should come with some 
>>>>> distinguishing syntax.
>>>>>
>>>>> In Python it's just [expr(x) for x in array]
>>>>> Which resonates with Pythons normal loopoing:
>>>>>    for x in array: expr(x)
>>>>>
>>>>> So direct translation of that idea to D would be
>>>>>    [expr(x) foreach(x; array)];
>>>>>
>>>>> Seems not so terrible a syntax to me.
>>>>>
>>>>> --bb
>>>>
>>>> I think I prefer:
>>>>
>>>> foo(array[]);
>>>
>>> I think that already means call foo with a full slice of array, 
>>> doesn't it?  Anyway, even if it doesn't you can overload opSlice() 
>>> currently so that array[] can mean anything you want it to.
>>>
>>> --bb
>>
>> That's the point though.  If there's already an overload available 
>> then that should be used.  It allows you to come along later and write 
>> specialized behavior.
> 
> Ok I suppose.  As long as you're aware what your proposing will break 
> existing code,  which means the barrier for accepting the proposal will 
> be a lot higher.
> 
> --bb

How?