R: Return both a Value and its Visibility

withVisible {base} | R Documentation

## 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

`x` | an expression to be evaluated.

### Details

The argument, not an `expression` object, rather an (unevaluated function) `call`, is evaluated in the caller's context.

This is a primitive function.

### Value

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

### See Also

`invisible`, `eval`; `withAutoprint()` calls `source()` which itself uses `withVisible()` in order to correctly “auto print”.

### Examples

    x <- 1
    withVisible(x <- 1) # *$visible is FALSE
    x
    withVisible(x)      # *$visible is TRUE

    # Wrap the call in evalq() for special handling

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

[Package base version 3.5.1 Index]