track_copy {pryr}

Track if an object is copied

Description

The title is somewhat misleading: rather than checking if an object is modified, this really checks to see if a name points to the same object.

Usage

track_copy(var, env = parent.frame(), quiet = FALSE)

Arguments

var

variable name (unquoted)

env

environment name in which to track changes

quiet

if FALSE, prints a message on change; if FALSE only the return value of the function is used

Value

a zero-arg function, that when called returns a boolean indicating if the object has changed since the last time this function was called

Examples

a <- 1:5
track_a <- track_copy(a)
track_a()
a[3] <- 3L
track_a()
a[3] <- 3
track_a()
rm(a)
track_a()