Array.AppendRange()

bgrommes

Problem

Sometimes you want to append one array to another. It's faster to have the runtime do it for you than to loop through the array and Append() individual items. Also the code becomes more concise and self-evident.

Proposed Solution

# _codePoints.AppendRange(codePointsToAppend)
# vs now:

For i As Integer = 0 To codePointsToAppend.LastIndex
  _codePoints.Append(codePointsToAppend[i])
Next

In .NET, the equivalent is List<T>.AddRange(IEnumerable<T>). This means the range of items doesn't have to be a List<T>, it just needs items of the same type. So AppendRange() would take an Iterable(Of T) (same T as the Array).

Alternatives Considered

The status quo

Who Would This Help?

Anyone writing clean performant code. I think particularly since we're running under a VM, anything the VM can do for us is a performance win.

Garry

Thanks for suggesting this. I agree this is a useful addition.

I’ve implemented this as Array.AppendAll(items) rather than AppendRange. That feels more Objo-like alongside the existing Append() and RemoveAll() methods.

Example:

Var codePoints() As Integer = [65, 66]
Var moreCodePoints() As Integer = [67, 68]

codePoints.AppendAll(moreCodePoints)
# codePoints is now [65, 66, 67, 68]

The method appends the source array’s elements to the receiver. The array remains a normal iterable array afterwards, so For Each works exactly as before.

Arrays of arrays are handled without flattening:

Var rows As Array(Of Array(Of Integer)) = [[1, 2], [3, 4]]
rows.AppendAll([[5, 6]])

Print(rows.Count) # 3
Print(rows[2][0]) # 5

Self-append is handled too: items.AppendAll(items) duplicates the original contents once.

This is implemented in the next release: https://feedback.objo.dev/feature/533