My Request helper or library

[eluser]slowgary[/eluser]
Exactly. Libraries are for classes, helpers and plugins are just procedural functions. Create a class with your functions, stick it in the application/libraries directory and load it with $this->load->library('request'), then you can call $this->request->isPost().

Just a recommendation, CodeIgniter uses_underscores as opposed to CamelCase. For consistency, you might want to consider naming your functions is_post(), is_get() and is_ajax().