How to distinguish helper functions from main functions in a package containing lot of functions? Is there a way to separate them by means of some standard identifier may be implemented in R?
For example, I am using sets package in my R session as follows. How would I separate helper functions from main functions from the list given below. I could do it by reading the documentation (sometimes it is explicitly documented a function as helper function), but is there is standard identifier implemented in R, to say that function is a helper or main function?
library(sets)
ls("package:sets")
[1] "%..%" "%<%" "%<=%"
[4] "%>%" "%D%" "%e%"
[7] "%is%" "as.cset" "as.gset"
[10] "as.interval" "as.set" "as.tuple"
[13] "binary_closure" "binary_reduction" "canonicalize_set_and_mapping"
[16] "charfun_generator" "closure" "cset"
[19] "cset_bound" "cset_cardinality" "cset_cartesian"
[22] "cset_charfun" "cset_combn" "cset_complement"
[25] "cset_concentrate" "cset_contains_element" "cset_core"
[28] "cset_defuzzify" "cset_difference" "cset_dilate"
[31] "cset_dissimilarity" "cset_has_missings" "cset_height"
[34] "cset_intersection" "cset_is_crisp" "cset_is_empty"
[37] "cset_is_equal" "cset_is_fuzzy_multiset" "cset_is_fuzzy_set"
[40] "cset_is_multiset" "cset_is_proper_subset" "cset_is_set"
[43] "cset_is_set_or_fuzzy_set" "cset_is_set_or_multiset" "cset_is_subset"
[46] "cset_matchfun" "cset_matchfun<-" "cset_mean"
[49] "cset_memberships" "cset_normalize" "cset_orderfun"
[52] "cset_orderfun<-" "cset_outer" "cset_peak"
[55] "cset_power" "cset_product" "cset_similarity"
[58] "cset_sum" "cset_support" "cset_symdiff"
[61] "cset_transform_memberships" "cset_union" "cset_universe"
[64] "e" "fuzzy_bell" "fuzzy_bell_gset"
[67] "fuzzy_cone" "fuzzy_cone_gset" "fuzzy_inference"
[70] "fuzzy_logic" "fuzzy_normal" "fuzzy_normal_gset"
[73] "fuzzy_partition" "fuzzy_pi3" "fuzzy_pi3_gset"
[76] "fuzzy_pi4" "fuzzy_pi4_gset" "fuzzy_rule"
[79] "fuzzy_sigmoid" "fuzzy_sigmoid_gset" "fuzzy_system"
[82] "fuzzy_trapezoid" "fuzzy_trapezoid_gset" "fuzzy_triangular"
[85] "fuzzy_triangular_gset" "fuzzy_tuple" "fuzzy_two_normals"
[88] "fuzzy_two_normals_gset" "fuzzy_variable" "gset"
[91] "gset_bound" "gset_cardinality" "gset_cartesian"
[94] "gset_charfun" "gset_combn" "gset_complement"
[97] "gset_concentrate" "gset_contains_element" "gset_core"
[100] "gset_defuzzify" "gset_difference" "gset_dilate"
[103] "gset_dissimilarity" "gset_has_missings" "gset_height"
[106] "gset_intersection" "gset_is_crisp" "gset_is_empty"
[109] "gset_is_equal" "gset_is_fuzzy_multiset" "gset_is_fuzzy_set"
[112] "gset_is_multiset" "gset_is_proper_subset" "gset_is_set"
[115] "gset_is_set_or_fuzzy_set" "gset_is_set_or_multiset" "gset_is_subset"
[118] "gset_mean" "gset_memberships" "gset_normalize"
[121] "gset_outer" "gset_peak" "gset_power"
[124] "gset_product" "gset_similarity" "gset_sum"
[127] "gset_support" "gset_symdiff" "gset_transform_memberships"
[130] "gset_union" "gset_universe" "integers"
[133] "integers2reals" "interval" "interval_complement"
[136] "interval_contains_element" "interval_difference" "interval_division"
[139] "interval_domain" "interval_intersection" "interval_is_bounded"
[142] "interval_is_closed" "interval_is_countable" "interval_is_degenerate"
[145] "interval_is_empty" "interval_is_equal" "interval_is_finite"
[148] "interval_is_greater_than" "interval_is_greater_than_or_equal" "interval_is_half_bounded"
[151] "interval_is_left_bounded" "interval_is_left_closed" "interval_is_left_open"
[154] "interval_is_left_unbounded" "interval_is_less_than" "interval_is_less_than_or_equal"
[157] "interval_is_proper" "interval_is_proper_subinterval" "interval_is_right_bounded"
[160] "interval_is_right_closed" "interval_is_right_open" "interval_is_right_unbounded"
[163] "interval_is_subinterval" "interval_is_unbounded" "interval_is_uncountable"
[166] "interval_measure" "interval_power" "interval_product"
[169] "interval_sum" "interval_symdiff" "interval_union"
[172] "is.charfun_generator" "is.cset" "is.gset"
[175] "is.interval" "is.set" "is.tuple"
[178] "is_element" "LABEL" "LABELS"
[181] "make_set_with_order" "matchfun" "naturals"
[184] "naturals0" "pair" "reals"
[187] "reals2integers" "reduction" "set"
[190] "set_cardinality" "set_cartesian" "set_combn"
[193] "set_complement" "set_contains_element" "set_dissimilarity"
[196] "set_intersection" "set_is_empty" "set_is_equal"
[199] "set_is_proper_subset" "set_is_subset" "set_outer"
[202] "set_power" "set_similarity" "set_symdiff"
[205] "set_union" "sets_options" "singleton"
[208] "triple" "tuple" "tuple_is_ntuple"
[211] "tuple_is_pair" "tuple_is_singleton" "tuple_is_triple"
[214] "tuple_outer"
Typically "helper" functions (defined as: functions used by main functions and typically not used by end users directly) are not exported and are not visible unless you use the package_name:::helper_function_name syntax. If a function is visible and documented it typically is a main function. So, if you want to see main functions, just use ls:
ls("package:sets")
If you want all functions (main + helper):
ls(getNamespace("sets"))
And finally, to get just helper functions, use setdiff:
setdiff(ls(getNamespace("sets")), ls("package:sets"))
See this SO Q/A for some discussion.
One potential ambiguity is that sometimes S3 methods are not explicitly exported, even if they are intended to be used as "main" functions.