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% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/helpers.R
\name{log_eval}
\alias{log_eval}
\title{Evaluate an expression and log results}
\usage{
log_eval(expr, level = TRACE, multiline = FALSE)
}
\arguments{
\item{expr}{R expression to be evaluated while logging the
expression itself along with the result}
\item{level}{\code{\link[=log_levels]{log_levels()}}}
\item{multiline}{setting to \code{FALSE} will print both the expression
(enforced to be on one line by removing line-breaks if any) and
its result on a single line separated by \verb{=>}, while setting to
\code{TRUE} will log the expression and the result in separate
sections reserving line-breaks and rendering the printed results}
}
\description{
Evaluate an expression and log results
}
\examples{
\dontshow{old <- logger:::namespaces_set()}
log_eval(pi * 2, level = INFO)
## lowering the log level threshold so that we don't have to set a higher level in log_eval
log_threshold(TRACE)
log_eval(x <- 4)
log_eval(sqrt(x))
## log_eval can be called in-line as well as returning the return value of the expression
x <- log_eval(mean(runif(1e3)))
x
## https://twitter.com/krlmlr/status/1067864829547999232
f <- sqrt
g <- mean
x <- 1:31
log_eval(f(g(x)), level = INFO)
log_eval(y <- f(g(x)), level = INFO)
## returning a function
log_eval(f <- sqrt)
log_eval(f)
## evaluating something returning a wall of "text"
log_eval(f <- log_eval)
log_eval(f <- log_eval, multiline = TRUE)
## doing something computationally intensive
log_eval(system.time(for (i in 1:100) mad(runif(1000))), multiline = TRUE)
\dontshow{logger:::namespaces_set(old)}
}
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