withVisible: Return both a value and its visibility

Description

This function evaluates an expression, returning it in a two element list containing its value and a flag showing whether it would automatically print.

Usage

withVisible(x)

Arguments

An expression to be evaluated.

Value

value: The value of x after evaluation.
visible: logical; whether the value would auto-print.

Details

The argument is evaluated in the caller's context.

This is a primitive function.

Examples

Run this code

x <- 1
withVisible(x <- 1)
x
withVisible(x)

# Wrap the call in evalq() for special handling

df <- data.frame(a = 1:5, b = 1:5)
evalq(withVisible(a + b), envir = df)