[R] paste argument of a function as a file name

[Luis Ridao Cruz]

R-help,

I have a function which is exporting the output to a file via
write.table(df, file =  "file name.xls" )

What I want is to paste the file name (above) by taking the argument to
the function as a file name 

something like this:

MY.function<- function(df)
{
...
...
write.table(df,"argument.xls")
}
MY.function(argument)


Thank you