Question about managing searching path

Hi all,
     I'm having sometrouble with managing the seach path, in a function , I need to attach some data set at the begining
and detach them at the end,  say,     myfunction<- function() { attach(mylist);      .............    detach(mylist) } ,
the problem is, since I am still debugging this code,  sometimes it got error and ended before reaching the end, thus
the data is left in the searching path.  
      What 's the right way to make mylist detached no matter what ?

Thanks a lot.

best