autoconf-style enable/disable options for a SCons file

SConstruct

def EnableableOption(name, default):
    AddOption("--enable-" + name,
        action="store_true", dest="en_" + name, default=False,
        help="Enables " + name)
    AddOption("--disable-" + name,
        action="store_true", dest="dis_" + name, default=False,
        help="Disables " + name)
    enable = GetOption("en_" + name)
    disable = GetOption("dis_" + name)
    if enable and disable:
        print("Warning: Both enable and disable " + name + " specified.")
        return default
    if disable:
        return False
    elif enable:
        return True
    else:
        return default

# In example:
enable_opengl2 = EnableableOption("opengl2", True)
enable_opengl4 = EnableableOption("opengl4", False)
enable_software = EnableableOption("software", False)
enable_vulkan = EnableableOption("vulkan", False)