Footer callback

README.md

@@ -554,6 +554,7 @@ There are several options that are supported on the main app and subcommands and
 -   `.positionals_at_end()`: 🆕 Specify that positional arguments occur as the last arguments and throw an error if an unexpected positional is encountered.
 -   `.prefix_command()`: Like `allow_extras`, but stop immediately on the first unrecognized item. It is ideal for allowing your app or subcommand to be a "prefix" to calling another app.
 -   `.footer(message)`: Set text to appear at the bottom of the help string.
+-   `.footer(std::string())`: 🚧 Set a callback to generate a string that will appear at the end of the help string.
 -   `.set_help_flag(name, message)`: Set the help flag name and message, returns a pointer to the created option.
 -   `.set_help_all_flag(name, message)`: Set the help all flag name and message, returns a pointer to the created option. Expands subcommands.
 -   `.failure_message(func)`: Set the failure message function. Two provided: `CLI::FailureMessage::help` and `CLI::FailureMessage::simple` (the default).

include/CLI/App.hpp

@@ -118,6 +118,9 @@ class App {
     /// Footer to put after all options in the help output INHERITABLE
     std::string footer_;
 
+    /// This is a function that generates a footer to put after all other options in help output
+    std::function<std::string()> footer_callback_;
+
     /// A pointer to the help flag if there is one INHERITABLE
     Option *help_ptr_{nullptr};
 
@@ -461,9 +464,8 @@ class App {
                 option->capture_default_str();
 
             return option.get();
-
-        } else
-            throw OptionAlreadyAdded(myopt.get_name());
+        }
+        throw OptionAlreadyAdded(myopt.get_name());
     }
 
     /// Add option for non-vectors (duplicate copy needed without defaulted to avoid `iostream << value`)
@@ -950,6 +952,7 @@ class App {
             remove_option(config_ptr_);
             config_name_ = "";
             config_required_ = false; // Not really needed, but complete
+            config_ptr_ = nullptr;    // need to remove the config_ptr completely
         }
 
         // Only add config if option passed
@@ -1423,25 +1426,23 @@ class App {
     /// Removes an option from the excludes list of this subcommand
     bool remove_excludes(Option *opt) {
         auto iterator = std::find(std::begin(exclude_options_), std::end(exclude_options_), opt);
-        if(iterator != std::end(exclude_options_)) {
-            exclude_options_.erase(iterator);
-            return true;
-        } else {
+        if(iterator == std::end(exclude_options_)) {
             return false;
         }
+        exclude_options_.erase(iterator);
+        return true;
     }
 
     /// Removes a subcommand from this excludes list of this subcommand
     bool remove_excludes(App *app) {
         auto iterator = std::find(std::begin(exclude_subcommands_), std::end(exclude_subcommands_), app);
-        if(iterator != std::end(exclude_subcommands_)) {
-            auto other_app = *iterator;
-            exclude_subcommands_.erase(iterator);
-            other_app->remove_excludes(this);
-            return true;
-        } else {
+        if(iterator == std::end(exclude_subcommands_)) {
             return false;
         }
+        auto other_app = *iterator;
+        exclude_subcommands_.erase(iterator);
+        other_app->remove_excludes(this);
+        return true;
     }
 
     ///@}
@@ -1453,7 +1454,11 @@ class App {
         footer_ = std::move(footer_string);
         return this;
     }
-
+    /// Set footer.
+    App *footer(std::function<std::string()> footer_function) {
+        footer_callback_ = std::move(footer_function);
+        return this;
+    }
     /// Produce a string that could be read in as a config of the current values of the App. Set default_also to
     /// include default arguments. Prefix will add a string to the beginning of each option.
     std::string config_to_str(bool default_also = false, bool write_description = false) const {
@@ -1470,10 +1475,10 @@ class App {
 
         // Delegate to subcommand if needed
         auto selected_subcommands = get_subcommands();
-        if(!selected_subcommands.empty())
+        if(!selected_subcommands.empty()) {
             return selected_subcommands.at(0)->help(prev, mode);
-        else
-            return formatter_->make_help(this, prev, mode);
+        }
+        return formatter_->make_help(this, prev, mode);
     }
 
     ///@}
@@ -1592,8 +1597,8 @@ class App {
     /// Get the group of this subcommand
     const std::string &get_group() const { return group_; }
 
-    /// Get footer.
-    const std::string &get_footer() const { return footer_; }
+    /// Generate and return the footer.
+    std::string get_footer() const { return (footer_callback_) ? footer_callback_() + '\n' + footer_ : footer_; }
 
     /// Get the required min subcommand value
     size_t get_require_subcommand_min() const { return require_subcommand_min_; }
@@ -2090,7 +2095,7 @@ class App {
         if(!(allow_extras_ || prefix_command_)) {
             size_t num_left_over = remaining_size();
             if(num_left_over > 0) {
-                throw ExtrasError(remaining(false));
+                throw ExtrasError(name_, remaining(false));
             }
         }
 
@@ -2107,7 +2112,7 @@ class App {
             size_t num_left_over = remaining_size();
             if(num_left_over > 0) {
                 args = remaining(false);
-                throw ExtrasError(args);
+                throw ExtrasError(name_, args);
             }
         }
 
@@ -2372,7 +2377,7 @@ class App {
         }
 
         if(positionals_at_end_) {
-            throw CLI::ExtrasError(args);
+            throw CLI::ExtrasError(name_, args);
         }
         /// If this is an option group don't deal with it
         if(parent_ != nullptr && name_.empty()) {

include/CLI/ConfigFwd.hpp

@@ -93,7 +93,8 @@ class Config {
 /// This converter works with INI files
 class ConfigINI : public Config {
   public:
-    std::string to_config(const App *, bool default_also, bool write_description, std::string prefix) const override;
+    std::string
+    to_config(const App * /*app*/, bool default_also, bool write_description, std::string prefix) const override;
 
     std::vector<ConfigItem> from_config(std::istream &input) const override {
         std::string line;

include/CLI/Error.hpp

@@ -206,32 +206,32 @@ class RequiredError : public ParseError {
     CLI11_ERROR_DEF(ParseError, RequiredError)
     explicit RequiredError(std::string name) : RequiredError(name + " is required", ExitCodes::RequiredError) {}
     static RequiredError Subcommand(size_t min_subcom) {
-        if(min_subcom == 1)
+        if(min_subcom == 1) {
             return RequiredError("A subcommand");
-        else
-            return RequiredError("Requires at least " + std::to_string(min_subcom) + " subcommands",
-                                 ExitCodes::RequiredError);
+        }
+        return RequiredError("Requires at least " + std::to_string(min_subcom) + " subcommands",
+                             ExitCodes::RequiredError);
     }
     static RequiredError Option(size_t min_option, size_t max_option, size_t used, const std::string &option_list) {
         if((min_option == 1) && (max_option == 1) && (used == 0))
             return RequiredError("Exactly 1 option from [" + option_list + "]");
-        else if((min_option == 1) && (max_option == 1) && (used > 1))
+        if((min_option == 1) && (max_option == 1) && (used > 1))
             return RequiredError("Exactly 1 option from [" + option_list + "] is required and " + std::to_string(used) +
                                      " were given",
                                  ExitCodes::RequiredError);
-        else if((min_option == 1) && (used == 0))
+        if((min_option == 1) && (used == 0))
             return RequiredError("At least 1 option from [" + option_list + "]");
-        else if(used < min_option)
+        if(used < min_option)
             return RequiredError("Requires at least " + std::to_string(min_option) + " options used and only " +
                                      std::to_string(used) + "were given from [" + option_list + "]",
                                  ExitCodes::RequiredError);
-        else if(max_option == 1)
+        if(max_option == 1)
             return RequiredError("Requires at most 1 options be given from [" + option_list + "]",
                                  ExitCodes::RequiredError);
-        else
-            return RequiredError("Requires at most " + std::to_string(max_option) + " options be used and " +
-                                     std::to_string(used) + "were given from [" + option_list + "]",
-                                 ExitCodes::RequiredError);
+
+        return RequiredError("Requires at most " + std::to_string(max_option) + " options be used and " +
+                                 std::to_string(used) + "were given from [" + option_list + "]",
+                             ExitCodes::RequiredError);
     }
 };
 
@@ -279,6 +279,12 @@ class ExtrasError : public ParseError {
                                        : "The following argument was not expected: ") +
                           detail::rjoin(args, " "),
                       ExitCodes::ExtrasError) {}
+    ExtrasError(const std::string &name, std::vector<std::string> args)
+        : ExtrasError(name,
+                      (args.size() > 1 ? "The following arguments were not expected: "
+                                       : "The following argument was not expected: ") +
+                          detail::rjoin(args, " "),
+                      ExitCodes::ExtrasError) {}
 };
 
 /// Thrown when extra values are found in an INI file

include/CLI/Formatter.hpp

@@ -28,8 +28,8 @@ inline std::string Formatter::make_positionals(const App *app) const {
 
     if(opts.empty())
         return std::string();
-    else
-        return make_group(get_label("Positionals"), true, opts);
+
+    return make_group(get_label("Positionals"), true, opts);
 }
 
 inline std::string Formatter::make_groups(const App *app, AppFormatMode mode) const {
@@ -126,10 +126,10 @@ inline std::string Formatter::make_usage(const App *app, std::string name) const
 
 inline std::string Formatter::make_footer(const App *app) const {
     std::string footer = app->get_footer();
-    if(!footer.empty())
-        return footer + "\n";
-    else
-        return "";
+    if(footer.empty()) {
+        return std::string{};
+    }
+    return footer + "\n";
 }
 
 inline std::string Formatter::make_help(const App *app, std::string name, AppFormatMode mode) const {
@@ -151,7 +151,7 @@ inline std::string Formatter::make_help(const App *app, std::string name, AppFor
     out << make_positionals(app);
     out << make_groups(app, mode);
     out << make_subcommands(app, mode);
-    out << make_footer(app);
+    out << '\n' << make_footer(app);
 
     return out.str();
 }
@@ -222,8 +222,8 @@ inline std::string Formatter::make_expanded(const App *sub) const {
 inline std::string Formatter::make_option_name(const Option *opt, bool is_positional) const {
     if(is_positional)
         return opt->get_name(true, false);
-    else
-        return opt->get_name(false, true);
+
+    return opt->get_name(false, true);
 }
 
 inline std::string Formatter::make_option_opts(const Option *opt) const {

include/CLI/FormatterFwd.hpp

@@ -144,7 +144,7 @@ class Formatter : public FormatterBase {
     virtual std::string make_usage(const App *app, std::string name) const;
 
     /// This puts everything together
-    std::string make_help(const App *, std::string, AppFormatMode) const override;
+    std::string make_help(const App * /*app*/, std::string, AppFormatMode) const override;
 
     ///@}
     /// @name Options