Format the usage text of functions


Formats the usage text of a function so that each line contains no more than a given number of characters.


format_funusage(x, name = "", width = 72, realname)



a character vector containing one element for each argument of the function, see ‘Details’.


the name of the function whose usage is described, a string.


maximal width of each line of output.


the printed form of name, see ‘Details’, a string.


format_funusage formats the usage text of a function for inclusion in Rd documentation files. If necessary, it splits the text into more lines in order to fit it within the requested width.

Each element of argument x contains the text for one argument of function name in the form arg or arg = default. format_funusage does not look into the content of x, it does the necessary pasting to form the complete usage text, inserting new lines and indentation to stay within the specified width. Elements of x are never split. If an argument (i.e., element of x) would cause the width to be exceeded, the entire argument is moved to the following line.

The text on the second and subsequent lines of each usage item starts in the column just after the opening parenthesis which follows the name of the function on the first line.

In descriptions of S3 methods and S4 methods, argument name may be a TeX macro like \method{print}{ts}. In that case the number of characters in name has little bearing on the actual number printed. In this case argument realname is used for counting both the number of characters on the first line of the usage message and the indentation for the subsequent lines.


The formatted text as a length one character vector.


Only the width of realname is used (for counting). The formatted text contains name.

The width of strings is determined by calling nchar with argument type set to "width".


Georgi N. Boshnakov

See Also



# this function is essentially internal,
# see deparse_usage1 and as.character.f_usage which use it.

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