readme

Readme.md

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+# Flags for C++
+This project aims to recreate the functionality of the `flag` package from Golang.
+
+## Usage
+### Create a parser
+```c++
+#include "flags.h"
+
+Parser parser;
+or
+// set the prefix and the help text
+Parser parser("--", "Help:");
+```
+
+### Declare a flag
+```c++
+// name, description, required, default value
+std::string* x = parser.add<std::string>("myStr", "some description", true, "default value");
+```
+
+### Parse arguments and show help text
+```c++
+if (!parser.parse(argc, argv))
+  parser.help();
+```
+
+### Declare a custom parser class
+```c++
+PARSER(MyTypeFlag, MyType, {
+  // parser body
+  // available variables:
+  //   MyType value;      <- storage for your value
+  //   std::string arg;   <- the next argument after the current flag
+  set_found(true);
+  try {
+    value = my_parser_function(arg);
+    set_found(true);
+  } catch(std::exception&) {}
+})
+
+parser.set_parser<MyType>(flag_constructor_t(MyTypeFlag::make));
+```
+
+## Built-in parsers
+- std::string
+- int (long, long long, unsigned long, unsigned long long)
+- float, double, long double
+- bool