Turn an expression to a label
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)
expr |
An expression to labellise. |
width |
Width of each line. |
nlines |
Maximum number of lines to extract. |
These functions are in the questioning stage because they are
redundant with the quo_
variants and do not handle quosures.
# To labellise a function argument, first capture it with # substitute(): fn <- function(x) expr_label(substitute(x)) fn(x:y) # Strings are encoded expr_label("a\nb") # Names and expressions are quoted with `` expr_label(quote(x)) expr_label(quote(a + b + c)) # Long expressions are collapsed expr_label(quote(foo({ 1 + 2 print(x) })))
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