Slices should append not overwrite

[the4thamigo-uk]

Proposed fix to cause slices to be appended to, rather than replaced. Also noticed that maps of slices don't seem to be working, so added unit tests for that as well.

fixes #35

[tzapu]

This is a wonderful feature to have included, thank you.

One question, would it not be more intuitive to append only if it’s not contained in the slice?

If you just want to update an object, you will get duplicates currently.

Cheers

[darccio]

@tzapu, this was already merged on January. About your question, what if we really want to merge all values, no matter what? Also, this is coherent with slices way of work, as appending to a slice doesn't look if the value already exists. Maps "append" checking by key and overwriting the existing value if key exists.

You can implement a Transformer to handle your case.

[tzapu]

hi, thanks, that's actually the route i went down on

package tripleutil

import (
	"reflect"
)

type SliceMerger struct {
}

func (am SliceMerger) Transformer(typ reflect.Type) func(dst, src reflect.Value) error {
	if typ.Kind() == reflect.Slice {
		return func(dst, src reflect.Value) error {

		next:
			for i := 0; i < src.Len(); i++ {
				for j := 0; j < dst.Len(); j++ {
					// not adding elements already found
					if reflect.DeepEqual(src.Index(i).Interface(), dst.Index(j).Interface()) {
						continue next
					}
				}
				// else we append it to destination
				dst.Set(reflect.Append(dst, src.Index(i)))
			}
			return nil
		}
	}
	return nil
}

if anyone else might need such a thing

thank you for this lovely piece of work :D

/edit: the above only works for merge, not merge with overwrite