Delay the evaluation of an expression until the end of a function or block.

Delay the evaluation of an expression until the end of a function or block.

Usage

delay(expr, envir = parent.frame(), add = TRUE, after = FALSE)

Arguments

expr

An expression to be evaluated later.

envir

The environment in which to evaluate the expression.

add

if TRUE, add expr to be executed after any previously set expressions (or before if after is FALSE); otherwise (the default) expr will overwrite any previously set expressions.

after

if add is TRUE and after is FALSE, then expr will be added on top of the expressions that were already registered. The resulting last in first out order is useful for freeing or closing resources in reverse order.

Value

None, called for its side-effects

Examples

local({
  x <- 1L
  delay(message("x = ", x))
  x <- 2L
})
#> x = 2