emit_message {messaging}

Provide a message with a consistent format

Description

Create a message using a message body that can be formed from multiple text objects. If a single text object is provided then the message will appear on a single line. If multiple text fragments are provided then they will be separated by newlines (in the order provided). Custom formatting is possible by providing a messaging template that uses the string expression scheme used in the glue package.

Usage

emit_message(..., .format = NULL, .f_name = TRUE, .issue = TRUE)

Arguments

...

a collection of string expressions and named arguments for string interpolation. Bare strings will be pasted together and separated by newlines. Named arguments are used to provide values for string interpolation in the message.

.format

a format template for a message. If not provided, the default template of "{.f_name}: {text}" will be used.

.f_name

the name of the function that relates to the message. If not provided, the function name will be obtained from the function call stack.

.issue

a logical value that indicates whether the message should be issued at all. This is to control for the verbosity of messages under certain circumstances.

Examples

# Write a function that yields a message with
# the requested number of info lines
yield_a_message <- function(msgs) {

  if (msgs > 3) msgs <- 3

  # Create some strings can serve as additional
  # info for the message
  message_components <-
    c("* message info 1",
      "* message info 2",
      "* message info 3")

  # Generate and emit a formatted message
  emit_message(
    "There (is/are) {number} thing(s) to note",
    message_components[1:msgs],
    number = msgs,
    .format = "{.f_name} info: {text}")
}

# When that function is called, a formatted
# message will appear; here are some examples:
yield_a_message(msgs = 3)

yield_a_message(msgs = 2)

yield_a_message(msgs = 1)