How to execute a funcition which name is stored in a string?

Hi, everybody

Is there any way to execute a function, which name is stored in a string.
such as:
a <- "ls()"
foo(a) ## same as ls() itself.

One way to accomplish this by using get() to search for a function
that matches your string. You can assign the return value of get() to
a variable which may be used like the original function object:
a <- 'ls'
foo <- get( a, mode = 'function' )
foo()
[1] "a" ? ? ? ? ?"foo"



-Charlie