我定义了一个函数:
.get <- function( o, ...) {
p <- match.call( expand.dots = 0)$...
cat( sprintf( 'In .get, it is %s.\n', eval( tail( p, 1)[[ 1]])))
fn <- switch( typeof( o), list =, environment = `[[`, 'S4' = '@', `[`)
if( length( p)) eval( as.call( c( fn, quote( o), p))) else o # Here when true, I compose a call based on p.
}
然后我尝试如下:
it <- 1
m <- matrix( seq( 9), 3)
sapply( seq( 3), function( it) {
cat( …