[R] how to define functions in such a situation

[Hu Chen]

hi R folks,
I need read a file from hardisk or www web. Then I need to define some
new functions according to the contents of the read file.
For  example, i need write a package name "mypackage" like this:
>library(mypackage)
>read(some_file_on_web) #to see its content, suppose it contains:
eat.drink.sleep
then 3 new functions need to be created and usable.
the problem is, how could I create functions after executing
">library(mypackage)" and make these new functions visible and usable
immediately?

Any information are appreciated. forgive me if this question is very
stupid. but I really need help.
Thank you all.