pseudotool

// Here's what we would change "tool_change" to look like:
int tool_change(int tool_num) {
    if (!call_hook("tool_change_pre", tool_num)) {
        old standard tool change precondition code; // error handling not shown
    }

    if (!call_hook("tool_change_do", tool_num)) {
        old standard tool change code; // error handling not shown
    }

    if (!call_hook("tool_change_post", tool_num) {
        old standard tool change postcondition code; // error handling not shown
    }
}

// And here's a Python implementation of a next-to-the-table tool changer
def tool_change_pre(int tool_num):
    release_current_tool() # not shown
    traverse(UNCHANGED, UNCHANGED, 2.0)
    traverse(toolchange_x, toolchange_y + tool_num * toolchange_dx, UNCHANGED)
    feed(UNCHANGED, UNCHANGED, 1.0, feedrate=12)
    set_digital_io(INDEX_TOOL_CLAMP, True)
    traverse(UNCHANGED, UNCHANGED, 2.0)
    return HANDLED