[R-pkg-devel] Analysing namespace reverse dependencies

[Iñaki Ucar]

On Sat, 9 Mar 2019 at 15:07, Roger Bivand <Roger.Bivand using nhh.no> wrote:
>
> Hi,
>
> Is anyone aware of tools permitting the listing of functions in the
> namespace of package A used by package B when package B declares that it
> depends on A, suggests A, or imports(A) without specifying the functions
> from A that B is using? If B imports functions from A, and uses
> importsFrom() in its NAMESPACE, the information can be recovered by
> inspecting its NAMESPACE file (assuming that the entries are correct), but
> not otherwise.

I don't know of any specific tool, but the following function may help:

inspect_functions <- function(pkg, from) {
  regex <- paste0("(", paste(from, collapse="|"), ")::[[:alnum:]._]*")
  ns <- getNamespace(pkg)
  x <- sapply(ls(ns, all.names=TRUE), function(x) {
    f <- get(x, envir=ns)
    if (!is.function(f))
      return(NULL)
    b <- unlist(strsplit(as.character(body(f)), "\n"))
    unique(regmatches(b, regexpr(regex, b)))
  })
  x[sapply(x, Negate(length))] <- NULL
  x
}

Example:

inspect_functions("units", c("pillar", "xml2"))
#> $.read_ud_db
#> [1] "xml2::read_xml"
#>
#> $.read_ud_db_symbols
#> [1] "xml2::read_xml"     "xml2::xml_find_all" "xml2::xml_contents"
#>
#> $.ud_db_xml_list_as_dataframe
#> [1] "xml2::xml_children" "xml2::xml_length"   "xml2::xml_find_all"
#> [4] "xml2::xml_text"
#>
#> $format_type_sum.type_sum_units
#> [1] "pillar::style_subtle"
#>
#> $pillar_shaft.mixed_units
#> [1] "pillar::new_pillar_shaft_simple"
#>
#> $pillar_shaft.units
#> [1] "pillar::new_pillar_shaft_simple"
#>
#> $valid_udunits_prefixes
#> [1] "xml2::xml_children" "xml2::xml_find_all" "xml2::xml_text"
#> [4] "xml2::xml_double"

Iñaki