Re: [Ocaml-lib-devel] Array interface

[John M. S. <sk...@oz...>]

Brian Hurt wrote:

> On Tue, 17 Jun 2003, John Skaller wrote:

>>Can't you initialise the empty slots with Obj.magic(0)?
>>
> No.  What if it's an array of floats, which is unboxed?


Ah.


> If you don't have a convient default, use a 'a option Dynarray.t.  


No way. That's a hack to support a faulty implementation.
I want a 'a Dynarray.t, the *filled* slots always have that type.
I don't see why I should change the type to suit an implementation
that can't handle the idea of a variable length array properly.

C++ vector does this correctly.

> Note: in the current API there is no way to get access to an element with 
> a null value.  So you don't ever have to worry about distinguishing null 
> values from sensible values.  So it's still safe if the null value would 
> otherwise have meaning.


I have examples where I CANNOT construct a dummy value.
The fact that the value is not accessible with
an array access cannot remove a requirement
an object may have to connect to other objects.

In particular, consider a type in which a representation
of an open file handle is stored. Now you force
me to create a dummy file in the file system just
to create an array.

It could be there is NO good solution in Ocaml.
In that case, use a C solution. I want this
data structure to work exactly right, and I need
it precisely *because* I can't define it myself.

-- 
John Max Skaller, mailto:sk...@oz...
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