Because assigning to array slices is possible, why dont D has an opSliceAssign?

-manfred

Manfred Nowak wrote:
> Because assigning to array slices is possible, why dont D has an opSliceAssign?
> 
> -manfred

Its a good question, and probably has something to do with determining the signature of the function.  Now that D has its "typesafe variadic arguments" I figure an opSliceAssign might look like:

# class Foo {
#   int[] data;
#
#   size_t opSliceAssign (in size_t begin, in size_t end, in int[] values...) {
#      size_t wall = values.length < end ? values.length : end;
#      for (size_t idx = begin; idx < wall; idx++)
#        data[idx] = values[idx - begin];
#      return wall - begin;
#   }
# }

-- Chris Sauls

"Manfred Nowak" <svv1999@hotmail.com> wrote in message news:de1lv7$1uln$1@digitaldaemon.com...
> Because assigning to array slices is possible, why dont D has an opSliceAssign?

I've asked this same question many times myself.

In article <de25l3$2n0u$1@digitaldaemon.com>, Jarrett Billingsley says...
>
>"Manfred Nowak" <svv1999@hotmail.com> wrote in message news:de1lv7$1uln$1@digitaldaemon.com...
>> Because assigning to array slices is possible, why dont D has an opSliceAssign?
>
>I've asked this same question many times myself.
>
>

I think the rationale for this is:

A slice is supposed to return another instance of the object with a subrange.
Because of the order of
operation, you can then assign to it, and opAssign would then take over IE:
foo[1..2] = 10 would be rewritten as:  foo.opSlice(1,2).opAssign(10)

However, this is not really a good thing.  Since if that's how normal slices
worked, using opslice to
imply a copy on normal arrays wouldn't work.  Normally when a slice operator is
used with an array as
an lvalue, it causes an array copy.  This is functionally objects cannot obtain
currently.


I vote for an opSliceAssign as well! :)

Chris Sauls wrote:
<snip>
> Its a good question, and probably has something to do with determining the signature of the function.  Now that D has its "typesafe variadic arguments" I figure an opSliceAssign might look like:
> 
> # class Foo {
> #   int[] data;
> #
> #   size_t opSliceAssign (in size_t begin, in size_t end, in int[] values...) {

Why the ...?  And why return a size_t?  And why not have the order match opIndexAssign?

    int[] opSliceAssign(int[] values, size_t begin, size_t end) { ... }

Stewart.

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Stewart Gordon wrote:
> Chris Sauls wrote:
> <snip>
> 
>> Its a good question, and probably has something to do with determining the signature of the function.  Now that D has its "typesafe variadic arguments" I figure an opSliceAssign might look like:
>>
>> # class Foo {
>> #   int[] data;
>> #
>> #   size_t opSliceAssign (in size_t begin, in size_t end, in int[] values...) {
> 
> 
> Why the ...?
I thought it was clever at the time... Now that I think about it, I guess it is kind of pointless.  A formal array would work fine.

> And why return a size_t?
I think I was envisioning it returning a length or something... honestly I forget what I was on to.

> And why not have the order match opIndexAssign?
That was just because of the variadic at the end.  Once that's gone, there's no reason, so yes it should match, just as you presented below.

> 
>     int[] opSliceAssign(int[] values, size_t begin, size_t end) { ... }
> 

-- Chris Sauls