Functional Programming in R 4 by Thomas Mailund

Author:Thomas Mailund
Language: eng
Format: epub
ISBN: 9781484294871
Publisher: Apress

Figure 4-7Evaluating with an explicit argument

We can exploit lazy evaluation to extract expressions rather than values and evaluate them in different environments, should we choose. A full exploration of this is beyond the scope of this book, but a short example could look like this:f <- function(expr, ...) {

expr <- substitute(expr) # Turn argument into a plain expression

env <- list2env(list(...)) # Make an env from '...'

parent.env(env) <- parent.frame() # Get remaining args from caller's env

eval(expr, env) # Now evaluate the expression in the new env

}

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