Based on this excellent question and replies, I learned you could use message(strwrap(<some message>)) to make the messages in the R package you write flow in the IDE nicely. But how do I go a step beyond reflow to a somewhat formatted message?
The accepted answer there suggests
message(strwrap(prefix = " ", initial = "",
"If you got to this point in the code, it means
the matrix was empty. Calculation continues but you should consider
re-evaluating an earlier step in the process"))
Which solves the OP's concern about maintaining spaces at newlines. But what if I wanted "Calculation continues" to actually start a new line, perhaps with a hard return between?
As indicated in the comments, adding initial = "\n" means new sentences begin on a new line:
message(strwrap(prefix = "\n", initial = "",
"If you got to this point in the code, it means
the matrix was empty. Calculation continues but you should consider
re-evaluating an earlier step in the process"))
outputting:
If you got to this point in the code, it means the matrix was empty.
Calculation continues but you should consider re-evaluating an earlier step in
the process
To add a hard return, one option is to add two newlines with "\n\n") in the message string:
message(strwrap(prefix = "\n", initial = "",
"If you got to this point in the code, it means
the matrix was empty.\n\nCalculation continues but you should consider
re-evaluating an earlier step in the process"))
outputting:
If you got to this point in the code, it means the matrix was empty.
Calculation continues but you should consider re-evaluating an earlier step in
the process