std.algorithm.find and array of needles?

[captaindet]

On 2014-03-03 14:58, John Colvin wrote:
> On Monday, 3 March 2014 at 19:35:53 UTC, captaindet wrote:
>> std.algorithm.find has an overload that works with several needles:
>>
>> // phobos doc example:
>> int[] a = [ 1, 4, 2, 3 ];
>> assert(find(a, [ 1, 3 ], 4) == tuple([ 4, 2, 3 ], 2));
>>
>> the function i want to write has to deal with variadic arguments serving as needles. unfortunately, i failed trying to make find work with the needles provided in an array:
>>
>> int[] a = [ 9, 8, 7, 6, 5, 4, 3, 2, 1 ];
>> int[][] ns = [ [ 7, 6 ], [ 4, 3 ] ];
>> auto res = find( a, ns );
>> //Error: template std.algorithm.find does not match any function template declaration. Candidates are:
>>
>> any ideas how this can be achieved?
>>
>> thanks
>> /det
>
> You can use a variadic template function instead of variadic slice construction:
>
> void foo(A, T ...)(A[] a, T ns)
> {
> //use find as follows. For example:
> return a.find(ns);
> }
>
> assert(foo([1,2,3,4], 3, 6, 2) == Tuple!([2,3,4], 2));

thanks, john.

i was afraid that this is the hoop i might have to jump through ;)

which is fine for the simple case i asked for. in another case, i would need to construct a needle proper from each pre-needle that is one the variadic arguments. this seems impossible now.

so i probably have to make the pre-needles template parameters and enter the dreadful realm of std.typetuple... guess staticMap is my friend here.


cheers
/det