class cBlockToEntityData
{
    public:
        Vector3i Position;
        int GetBlockType(); // returns E_BLOCK type
        int GetMetaData(); // returns E_META data
        cBlockInfo GetBlockInfo(); // returns a cBlockInfo
        // Excuse my lack of knowledge of the internals of MCServer...
}

function OnExploding(World, ExplosionSize, CanCauseFire, X, Y, Z, Source, SourceData, AffectedBlocks)
    -- AffectedBlocks is a table full of cBlockToEntityData
    for n, k in pairs(AffectedBlocks) do
        if k:GetBlockType() == E_BLOCK_DIRT then
            table.remove(AffectedBlocks, n)
        end
    end
    -- send the modified table to the server to be processed
end

function OnExploding(World, ExplosionSize, CanCauseFire, X, Y, Z, Source, SourceData, AffectedBlocks)
    assert(tolua.type(AffectedBlocks) == "cBlockArray")  -- It is an object with its own operations

    -- Example: do NOT explode dirt:
    for n = AffectedBlocks.GetCount() - 1, 0, -1 do  -- count from GetCount() - 1 down to 0
        if (AffectedBlock:GetBlockType(n) == E_BLOCK_DIRT) then  -- Get the n-th block's type
            AffectedBlocks.Remove(n)
        end
    end
    return false
end