Generating an explicit .lintr.R file

[TimTaylor]

Would there be interest in providing a function that generates an explicit (e.g. defaults explicitly listed and commented) .lintr.R configuration. These could be pre-populated templates within the package or generated by users at runtime.

The motivation for this is that an explicit format makes it clear to new (and probably old) users what lints are going to be run and, if commentary is also supplied, what those lints do. Of course there are drawbacks to the explicit approach (e.g. a need to regenerate the file with new releases) but I think the option could be useful.

Some code I've been playing with is shared below. At the moment it is purely set to print out and comment all linters but there is no reason it couldn't handle customisation and NULLing of linters as with the other functions.

generate_all_linters <- function(filename, ...) {
    # TODO - filename checks
    # TODO - changing lint defaults / excluding lints
    # TODO - alternative to tools:::.Rd_get_metadata that will convert description to nicely formatted text

    names <- .subset2(lintr::available_linters(), "linter")
    namespace <- loadNamespace("lintr")
    call <- lapply(names, function(x) c(as.symbol(x), formals(x, namespace)))
    call <- sapply(call, function(x) deparse1(as.call(x)))

    rddb <- tools::Rd_db("lintr")
    desc <- sapply(rddb, tools:::.Rd_get_metadata, "description")
    names(desc) <- sub(".Rd$", "", names(desc), perl = TRUE)
    desc <- desc[names]
    desc <- gsub(pattern = "\n", replacement = " ", x = desc, perl = TRUE)
    desc <- gsub(pattern = "[[:blank:]]{2,}", replacement = " ", x = desc, perl = TRUE)
    desc <- lapply(desc, strwrap, width = 80)
    desc <- lapply(desc, function(x) paste("    #", x, collapse = "\n"))

    cat("linters <- list(\n", file = filename)
    for (i in seq_along(call)) {
        cat(desc[[i]], file = filename, append = TRUE)
        txt <- sprintf("\n    %s%s", call[[i]], if (i == length(call)) "\n)" else ",\n\n")
        cat(txt, file = filename, append = TRUE)
    }
    invisible(filename)
}

I'm happy to pursue this further in a draft PR but no worries if not desirable / out of scope.

[AshesITR]

This may be well integrated into use_lintr() once we're committed to this type of configuration.

[TimTaylor]

Cool. FWIW - I've tidied up this function for myself (better formatting and accompanying lint documentation) over at https://github.com/TimTaylor/lintrall/blob/main/pkg/R/use_all_linters.R. I've also added a copy of what it currently generates at https://github.com/TimTaylor/lintrall/blob/main/pkg/inst/Example/.lintr.R in case you want to peruse.