CodeIgniter uses a series of functions and names in its operation. Because of this, some names cannot be used by a developer. Following is a list of reserved names that cannot be used.
Controller names
Since your controller classes will extend the main application controller you must be careful not to name your functions identically to the ones used by that class, otherwise your local functions will override them. The following is a list of reserved names. Do not name your controller any of these:
Controller
CI_Base
_ci_initialize
Default
index
Functions
is_really_writable()
load_class()
get_config()
config_item()
show_error()
show_404()
log_message()
_exception_handler()
get_instance()
Variables
$config
$mimes
$lang
Constants
ENVIRONMENT
EXT
FCPATH
SELF
BASEPATH
APPPATH
CI_VERSION
FILE_READ_MODE
FILE_WRITE_MODE
DIR_READ_MODE
DIR_WRITE_MODE
FOPEN_READ
FOPEN_READ_WRITE
FOPEN_WRITE_CREATE_DESTRUCTIVE
FOPEN_READ_WRITE_CREATE_DESTRUCTIVE
FOPEN_WRITE_CREATE
FOPEN_READ_WRITE_CREATE
FOPEN_WRITE_CREATE_STRICT
FOPEN_READ_WRITE_CREATE_STRICT