[R] the difference between UseMethod and NextMehod?

[Gabor Grothendieck]

ronggui <0034058 <at> fudan.edu.cn> writes:

: hi,usRs,i am studing the R programming,but i can not get the point abut the 
difference between UseMethod
: and NextMehod.i have read the manual and try to find the solutin from 
internet,but i still not master it
: well.so anyone can give me a guide?it will be better to show some examples .


One normally uses UseMethod within a generic function to dispatch
the appropriate method while NextMethod is normally used within the 
function so dispatched.

An important difference is that UseMethod does not return, i.e.
statements after UseMethod are not evaluated, whereas NextMethod 
does return.

Have a look at print and print.ts for examples of UseMethod and
NextMethod, respectively.  Just type the following at the R prompt:

print
print.ts