feat: 'set_defaults()', 'format_help()', and 'format_usage()'

* We now support the `format_help()`, `format_usage()`, and `set_defaults()` methods (#43).
  Suggestion of @oliverbothe.

closes #43

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: argparse
 Type: Package
 Title: Command Line Optional and Positional Argument Parser
-Version: 2.1.7-2
+Version: 2.2.0-0
 Authors@R: c(person("Trevor L", "Davis", role=c("aut", "cre"),
              email="[email protected]",
              comment = c(ORCID = "0000-0001-6341-4639")),

NEWS.md

@@ -1,6 +1,9 @@
-argparse 2.1.7
+argparse 2.2.0
 ==============
 
+* We now support the `format_help()`, `format_usage()`, and `set_defaults()` methods (#43).
+  Suggestion of @oliverbothe.
+
 * When an error is thrown by `ArgumentParser()$parse_args()` and `interactive()` is `FALSE`
   and `getOption("error")` is `NULL` then
   we now use a quieter default error handler that doesn't output a trailing "Execution halted".

R/argparse.R

@@ -151,6 +151,14 @@ Parser <- R6Class("Parser", # nolint
             output <- private$python_code$run(new_code)
             parse_args_output(output)
         },
+        format_help = function() {
+            paste(private$python_code$run(sprintf("%s.print_help()", private$name)),
+                  collapse = "\n")
+        },
+        format_usage = function() {
+            paste(private$python_code$run(sprintf("%s.print_usage()", private$name)),
+                  collapse = "\n")
+        },
         print_help = function() {
             cat(private$python_code$run(sprintf("%s.print_help()", private$name)), sep = "\n")
             invisible(NULL)
@@ -159,6 +167,14 @@ Parser <- R6Class("Parser", # nolint
             cat(private$python_code$run(sprintf("%s.print_usage()", private$name)), sep = "\n")
             invisible(NULL)
         },
+        get_default = function(...) {
+            stop("We don't currently support `get_default()`")
+        },
+        set_defaults = function(...) {
+            private$python_code$append(sprintf("%s.set_defaults(%s)", private$name,
+                            convert_..._to_arguments("add_argument", ...)))
+            invisible(NULL)
+        },
         add_argument = function(...) {
             private$python_code$append(sprintf("%s.add_argument(%s)", private$name,
                             convert_..._to_arguments("add_argument", ...)))

tests/testthat/test-argparse.R

@@ -26,6 +26,8 @@ test_that("print_help works as expected", {
     expect_output(parser$print_help(), "optional arguments:|options:")
     expect_output(parser$print_help(), "Process some integers.")
     expect_output(parser$print_usage(), "usage:")
+    expect_true(grepl("Process some integers.", parser$format_help()))
+    expect_true(grepl("usage:", parser$format_usage()))
 
     # Request/bug by PlasmaBinturong
     parser$add_argument("integers", metavar = "N", type = "integer", nargs = "+",
@@ -151,7 +153,15 @@ test_that("parse_known_args() works as expected", {
 
 })
 
+test_that("set_defaults() works as expected", {
+    skip_if_not(detects_python())
+    parser <- ArgumentParser()
+    parser$set_defaults(bar=42)
+    args <- parser$parse_args(c())
+    expect_equal(args$bar, 42)
 
+    # expect_equal(parser$get_default("bar"), 42)
+})
 
 test_that("ArgumentParser works as expected", {
     skip_if_not(detects_python())