expr_text() turns the expression into a single string, which might be multi-line. expr_name() is suitable for formatting names. It works best with symbols and scalar types, but also accepts calls. expr_label() formats the expression nicely for use in messages.

expr_label(expr)

expr_name(expr)

expr_text(expr, width = 60L, nlines = Inf)

Arguments

expr

An expression to labellise.

width

Width of each line.

nlines

Maximum number of lines to extract.

Examples

# To labellise a function argument, first capture it with # substitute(): fn <- function(x) expr_label(substitute(x)) fn(x:y)
#> [1] "`x:y`"
# Strings are encoded expr_label("a\nb")
#> [1] "\"a\\nb\""
# Names and expressions are quoted with `` expr_label(quote(x))
#> [1] "`x`"
expr_label(quote(a + b + c))
#> [1] "`a + b + c`"
# Long expressions are collapsed expr_label(quote(foo({ 1 + 2 print(x) })))
#> [1] "`foo(...)`"