Add opt-out for --no-* boolean switch aliases

NEWS.md

@@ -1,5 +1,8 @@
 # Rapp (development version)
 
+-   Boolean switches annotated with `#| negative_alias: false` no longer include
+    or accept a generated `--no-*` alias (#24).
+
 # Rapp 0.3.0
 
 ## Breaking changes
@@ -26,4 +29,3 @@
 # Rapp 0.1.0
 
 -   Initial release
-

R/args.R

@@ -91,8 +91,9 @@ process_args <- function(args, app) {
       # if flag not known, maybe this is a switch flag
       if (is.null(spec) && startsWith(a, "--no-")) {
         alt_name <- str_drop_prefix(name, "no_")
-        spec <- app_opts[[alt_name]]
-        if (!is.null(spec)) {
+        alt_spec <- app_opts[[alt_name]]
+        if (!is.null(alt_spec) && has_negative_alias(alt_spec)) {
+          spec <- alt_spec
           val <- "false"
           name <- alt_name
         }
@@ -198,9 +199,14 @@ process_args <- function(args, app) {
     }
 
     if (length(specs) < length(positional_args)) {
+      unknown_args <- if (length(specs)) {
+        positional_args[-seq_along(specs)]
+      } else {
+        positional_args
+      }
       stop(
         "Arguments not recognized: ",
-        paste0(positional_args[-seq_along(specs)], collapse = " ")
+        paste0(unknown_args, collapse = " ")
       )
     }
 

R/help.R

@@ -177,16 +177,23 @@ print_app_help <- function(app, yaml = TRUE, command_path = character()) {
     } else if (identical(opt$arg_type, "switch")) {
       default_value <- format_default_value(opt$default)
       toggle_flag <- paste0("--no-", cli_name)
+      show_negative <- has_negative_alias(opt)
       toggle_note <- if (isTRUE(opt$default)) {
-        sprintf("Disable with `%s`.", toggle_flag)
+        if (show_negative) {
+          sprintf("Disable with `%s`.", toggle_flag)
+        } else {
+          character()
+        }
       } else {
         sprintf("Enable with `%s`.", paste0("--", cli_name))
       }
       if (!is.null(default_value)) {
         details <- c(details, sprintf("[default: %s]", default_value))
       }
       details <- c(details, toggle_note)
-      flag <- paste(flag, "/", toggle_flag)
+      if (show_negative) {
+        flag <- paste(flag, "/", toggle_flag)
+      }
     }
 
     if (identical(opt$action, "append")) {

R/utils.R

@@ -68,6 +68,8 @@ compact <- function(x) x[lengths(x) > 0]
 `%||%` <- function(x, y) if (is.null(x)) y else x
 `subtract<-` <- function(x, value) x - value
 
+has_negative_alias <- function(opt) !isFALSE(opt[["negative_alias"]])
+
 `append<-` <- function(x, after = NULL, value) {
   if (is.null(after)) c(x, value) else append(x, value, after)
 }

README.md

@@ -130,6 +130,15 @@ my-app --echo=false  # FALSE
 my-app --echo=0      # FALSE
 ```
 
+To omit the generated `--no-*` alias for a boolean switch, add
+`#| negative_alias: false` above the assignment:
+
+``` r
+#| description: Print version and exit.
+#| negative_alias: false
+version <- FALSE
+```
+
 Assigning `c()` or `list()` declares an option that can be supplied
 multiple times. Use `c()` when you want to keep the exact strings
 provided on the command line, and `list()` when you want Rapp to attempt
@@ -338,6 +347,8 @@ Other YAML fields you can supply to change the behavior of Rapp
 - `arg_type`: how the input appears on the CLI (`option`, `switch`, `positional`).
 - `action`: whether values replace or accumulate (`replace` vs `append` for
   repeatable options and collectors).
+- `negative_alias`: whether boolean switches include a generated `--no-*`
+  alias.
 
 ## Summary
 

tests/testthat/test-regressions.R

@@ -98,3 +98,60 @@ test_that("leading variadic positional collectors accumulate args", {
 
   expect_output(Rapp::run(app_path, c("alpha", "beta", "gamma")), "ok")
 })
+
+test_that("boolean switches can disable negative aliases", {
+  app_path <- local_rapp_app(
+    c(
+      "#!/usr/bin/env Rapp",
+      "#| name: version-app",
+      "#| description: Version printer.",
+      "",
+      "#| description: Print version and exit.",
+      "#| negative_alias: false",
+      "version <- FALSE",
+      "",
+      "if (version) cat('version-app 1.0.0\\n')"
+    ),
+    prefix = "rapp-no-negative-switch-"
+  )
+
+  expect_output(Rapp::run(app_path, "--version"), "version-app 1.0.0")
+
+  help <- capture.output(Rapp::run(app_path, "--help"))
+  expect_true(any(grepl("--version", help, fixed = TRUE)))
+  expect_false(any(grepl("--no-version", help, fixed = TRUE)))
+  expect_error(
+    Rapp::run(app_path, "--no-version"),
+    "Arguments not recognized: --no-version",
+    fixed = TRUE
+  )
+
+  true_default_app <- local_rapp_app(
+    c(
+      "#!/usr/bin/env Rapp",
+      "#| description: Keep output wrapped.",
+      "#| negative_alias: false",
+      "wrap <- TRUE"
+    ),
+    prefix = "rapp-no-negative-default-true-"
+  )
+  true_default_help <- capture.output(Rapp::run(true_default_app, "--help"))
+  expect_false(any(grepl("--no-wrap", true_default_help, fixed = TRUE)))
+  expect_false(any(grepl(
+    "Enable with `--wrap`.",
+    true_default_help,
+    fixed = TRUE
+  )))
+
+  negative_app <- local_rapp_app(
+    c(
+      "#!/usr/bin/env Rapp",
+      "#| description: Legacy spelling is ignored.",
+      "#| negative: false",
+      "legacy <- FALSE"
+    ),
+    prefix = "rapp-negative-ignored-"
+  )
+  negative_help <- capture.output(Rapp::run(negative_app, "--help"))
+  expect_true(any(grepl("--no-legacy", negative_help, fixed = TRUE)))
+})