On Mon, Apr 30, 2012 at 11:46:09AM +0400, Dmitry Olshansky wrote:
> On 30.04.2012 9:33, H. S. Teoh wrote:
[...]
> >I think the latter area has lots of room for improvement. From a
> >theoretical standpoint, syntax like [1,2,3,4,5] really should not be
> >prematurely tied to a specific type: at the most fundamental level,
> >it's just specifying a list of things. How the abstract concept of a
> >list of things should be implemented need not be constrained to
> >concrete built-in types; I'd argue that the language should permit
> >the realization of the concept in a user-defined type as well (i.e.,
> >the literal interpreted by a user type).
> >
> >Just off the top of my head, this might be achievable by introducing
> >a fromList method in user-defined types that takes a compile-time
> >parameter containing some representation of the list, say as a
> >builtin array. This method then does whatever is needed to create an
> >instance of the type accordingly. (Since the parameter is
> >compile-time, this essentially just generates code to create the
> >custom container directly.)
[...]
> *cough* initializer lists *cough*
>
> Seriously let AA liters be an sorted initializer list (conceptual
> compile-time array) of pairs, and normal array literal just plain
> initializer list of common type.
>
> This also nails nicely strange use case of AA literal to build array
> (just the same sorted table of pairs!). The AA then is just
> initialized with sorted array at run-time. (as it does anyway)
[...]
+1, this is an excellent idea!
It also solves the case of byte[], uint[], int[], etc., all being
initializable by "[1,2,3]". Currently, subtle bugs are introduced in
certain contexts by the compiler interpreting [1,2,3] to be int[] by
default. What we really should do is to pass it in as a compile-time
initializer list to the relevant ctors. So byte[].this() will interpret
[1,2,3] as bytes, uint[].this() will interpret it as uints, etc.. Then
you can write:
uint[] a = [
2: 100,
10: 200
]
and it will be equivalent to:
uint[] a = [0, 0, 100, 0, 0, 0, 0, 0, 0, 0, 200];
T
--
The most powerful one-line C program: #include "/dev/tty" -- IOCCC
