fix a few issues with config file output,

README.md

@@ -758,7 +758,7 @@ If it is desired that multiple configuration be allowed.  Use
 app.set_config("--config")->expected(1, X);
 ```
 
-Where X is some positive number and will allow up to `X` configuration files to be specified by separate `--config` arguments.
+Where X is some positive number and will allow up to `X` configuration files to be specified by separate `--config` arguments.  Value strings with quote characters in it will be printed with a single quote.🚧  All other arguments will use double quote.  Empty strings will use a double quoted argument.🚧  Numerical or boolean values are not quoted. 🚧
 
 ### Inheriting defaults
 

examples/CMakeLists.txt

@@ -81,6 +81,22 @@ add_test(NAME subcom_partitioned_help COMMAND subcom_partitioned --help)
 set_property(TEST subcom_partitioned_help PROPERTY PASS_REGULAR_EXPRESSION
                                                    "-f,--file TEXT REQUIRED" "-d,--double FLOAT")
 
+####################################################
+add_cli_exe(config_app config_app.cpp)
+add_test(NAME config_app1 COMMAND config_app -p)
+set_property(TEST config_app1 PROPERTY PASS_REGULAR_EXPRESSION "file=")
+
+add_test(NAME config_app2 COMMAND config_app -p -f /)
+set_property(TEST config_app2 PROPERTY PASS_REGULAR_EXPRESSION "file=\"/\"")
+
+add_test(NAME config_app3 COMMAND config_app -f "" -p)
+set_property(TEST config_app3 PROPERTY PASS_REGULAR_EXPRESSION "file=\"\"")
+
+add_test(NAME config_app4 COMMAND config_app -f "/" -p)
+set_property(TEST config_app4 PROPERTY PASS_REGULAR_EXPRESSION "file=\"/\"")
+
+####################################################
+
 add_cli_exe(option_groups option_groups.cpp)
 add_test(NAME option_groups_missing COMMAND option_groups)
 set_property(TEST option_groups_missing PROPERTY PASS_REGULAR_EXPRESSION "Exactly 1 option from"

examples/config_app.cpp

@@ -0,0 +1,50 @@
+// Copyright (c) 2017-2020, University of Cincinnati, developed by Henry Schreiner
+// under NSF AWARD 1414736 and by the respective contributors.
+// All rights reserved.
+//
+// SPDX-License-Identifier: BSD-3-Clause
+
+#include <CLI/CLI.hpp>
+#include <iostream>
+#include <string>
+
+int main(int argc, char **argv) {
+
+    CLI::App app("configuration print example");
+
+    app.add_flag("-p,--print", "Print configuration and exit")->configurable(false);  // NEW: print flag
+
+    std::string file;
+    CLI::Option *opt = app.add_option("-f,--file,file", file, "File name")
+                           ->capture_default_str()
+                           ->run_callback_for_default();  // NEW: capture_default_str()
+
+    int count{0};
+    CLI::Option *copt =
+        app.add_option("-c,--count", count, "Counter")->capture_default_str();  // NEW: capture_default_str()
+
+    int v{0};
+    CLI::Option *flag = app.add_flag("--flag", v, "Some flag that can be passed multiple times")
+                            ->capture_default_str();  // NEW: capture_default_str()
+
+    double value{0.0};                                                          // = 3.14;
+    app.add_option("-d,--double", value, "Some Value")->capture_default_str();  // NEW: capture_default_str()
+
+    app.get_config_formatter_base()->quoteCharacter('"', '"');
+
+    CLI11_PARSE(app, argc, argv);
+
+    if(app.get_option("--print")->as<bool>()) {  // NEW: print configuration and exit
+        std::cout << app.config_to_str(true, false);
+        return 0;
+    }
+
+    std::cout << "Working on file: " << file << ", direct count: " << app.count("--file")
+              << ", opt count: " << opt->count() << std::endl;
+    std::cout << "Working on count: " << count << ", direct count: " << app.count("--count")
+              << ", opt count: " << copt->count() << std::endl;
+    std::cout << "Received flag: " << v << " (" << flag->count() << ") times\n";
+    std::cout << "Some value: " << value << std::endl;
+
+    return 0;
+}

include/CLI/Config.hpp

@@ -23,9 +23,9 @@ namespace CLI {
 // [CLI11:config_hpp:verbatim]
 namespace detail {
 
-inline std::string convert_arg_for_ini(const std::string &arg) {
+inline std::string convert_arg_for_ini(const std::string &arg, char stringQuote = '"', char characterQuote = '\'') {
     if(arg.empty()) {
-        return std::string(2, '"');
+        return std::string(2, stringQuote);
     }
     // some specifically supported strings
     if(arg == "true" || arg == "false" || arg == "nan" || arg == "inf") {
@@ -40,7 +40,7 @@ inline std::string convert_arg_for_ini(const std::string &arg) {
     }
     // just quote a single non numeric character
     if(arg.size() == 1) {
-        return std::string("'") + arg + '\'';
+        return std::string(1, characterQuote) + arg + characterQuote;
     }
     // handle hex, binary or octal arguments
     if(arg.front() == '0') {
@@ -60,16 +60,20 @@ inline std::string convert_arg_for_ini(const std::string &arg) {
             }
         }
     }
-    if(arg.find_first_of('"') == std::string::npos) {
-        return std::string("\"") + arg + '"';
+    if(arg.find_first_of(stringQuote) == std::string::npos) {
+        return std::string(1, stringQuote) + arg + stringQuote;
     } else {
-        return std::string("'") + arg + '\'';
+        return characterQuote + arg + characterQuote;
     }
 }
 
 /// Comma separated join, adds quotes if needed
-inline std::string
-ini_join(const std::vector<std::string> &args, char sepChar = ',', char arrayStart = '[', char arrayEnd = ']') {
+inline std::string ini_join(const std::vector<std::string> &args,
+                            char sepChar = ',',
+                            char arrayStart = '[',
+                            char arrayEnd = ']',
+                            char stringQuote = '"',
+                            char characterQuote = '\'') {
     std::string joined;
     if(args.size() > 1 && arrayStart != '\0') {
         joined.push_back(arrayStart);
@@ -82,7 +86,7 @@ ini_join(const std::vector<std::string> &args, char sepChar = ',', char arraySta
                 joined.push_back(' ');
             }
         }
-        joined.append(convert_arg_for_ini(arg));
+        joined.append(convert_arg_for_ini(arg, stringQuote, characterQuote));
     }
     if(args.size() > 1 && arrayEnd != '\0') {
         joined.push_back(arrayEnd);
@@ -296,13 +300,16 @@ ConfigBase::to_config(const App *app, bool default_also, bool write_description,
                     }
                 }
                 std::string name = prefix + opt->get_single_name();
-                std::string value = detail::ini_join(opt->reduced_results(), arraySeparator, arrayStart, arrayEnd);
+                std::string value = detail::ini_join(
+                    opt->reduced_results(), arraySeparator, arrayStart, arrayEnd, stringQuote, characterQuote);
 
                 if(value.empty() && default_also) {
                     if(!opt->get_default_str().empty()) {
-                        value = detail::convert_arg_for_ini(opt->get_default_str());
+                        value = detail::convert_arg_for_ini(opt->get_default_str(), stringQuote, characterQuote);
                     } else if(opt->get_expected_min() == 0) {
                         value = "false";
+                    } else if(opt->get_run_callback_for_default()) {
+                        value = "\"\"";  // empty string default value
                     }
                 }
 

include/CLI/ConfigFwd.hpp

@@ -87,6 +87,10 @@ class ConfigBase : public Config {
     char arraySeparator = ',';
     /// the character used separate the name from the value
     char valueDelimiter = '=';
+    /// the character to use around strings
+    char stringQuote = '"';
+    /// the character to use around single characters
+    char characterQuote = '\'';
 
   public:
     std::string
@@ -114,6 +118,12 @@ class ConfigBase : public Config {
         valueDelimiter = vSep;
         return this;
     }
+    /// Specify the quote characters used around strings and characters
+    ConfigBase *quoteCharacter(char qString, char qChar) {
+        stringQuote = qString;
+        characterQuote = qChar;
+        return this;
+    }
 };
 
 /// the default Config is the TOML file format