Consider interface to filling data into already allocated arrays about netcdf

[bluss]

I'm watching for this feature as well. I have been using an untyped (*const u8) interface and would be interested in that kind of low level interface as well, or enough low level access that it can be implemented using the right variable ids with the netcdf-sys interface.

[evomassiny]

Hi,
I've implemented an alternative to values_at and values that can be used with a pre-allocated vector, see the related PR.
As for the equivalent of array_at, I don't know how to mutate the raw data of an ArrayD.

@bluss The netcdf-sys interface expose all the "nc_get_vara_*" fonction familly from the original C library, Is this what you need ?

[bluss]

Sure, I'm thinking of nc_get_vara which uses a void *. I have a prototype (using netcdf-sys) that is using it:

    /// Read variable data of any type; without conversion
    ///
    /// # Safety
    ///
    /// The caller must ensure that `ptr` points to a place where the output can
    /// be written safely.
    pub unsafe fn read_at(&self, indices: &[size_type], counts: &[size_type], ptr: *mut u8) -> Result<(), Ety>
    {
        netcdf_lock!();
        check(ns::nc_get_vara(self.group_id, self.id, indices.as_ptr(), counts.as_ptr(), ptr as _))
    }

I have been struggling to find the right way to work with a "foreign typesystem" (netCDF types in this case) and sometimes using enums everywhere seems both redundant and restrictive. The C approach to "generic" is sometimes really effective. That said, I haven't exactly settled on either way to solve it.

[mhiley]

closed by #21