Extending library different behavior and problems

[eluser]minttux[/eluser]
Sorry for late answer
i should made example for explain better this problem and now i made it
i extended log.php library
execute it and compare result when you put MYO_log.php in core and libraries
and yes because i separate my files with my prefix so for overwrite codeigniter files i used MYO_ prefix that is short of MY Overwrite and i set in config files

make sure log folder permission is 777
i use log_message('error', 'my own log'); in welcome.php controller to produce my own log so run the script one time when you put MYO_log.php in core and one time when you put in libraries

and you will see when it placed in libraries worked but in core doesn't work and load default log.php inside system folder

i put application folder also i have total project if you don't want replace with your own application folder
but you should download here https://docs.google.com/file/d/0B6rI2pr0...sp=sharing

Thanks