From e0a66de87d135a5f8acde048219cb0c1510d5df1 Mon Sep 17 00:00:00 2001 From: Irvin Cardoza <86453572+irvincardoza@users.noreply.github.com> Date: Mon, 9 Dec 2024 12:55:36 -0800 Subject: [PATCH] Create Clara.md created docs of Clara inside, fixing issue #2312 --- docs/Clara.md | 101 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 101 insertions(+) create mode 100644 docs/Clara.md diff --git a/docs/Clara.md b/docs/Clara.md new file mode 100644 index 00000000..8c4af7a5 --- /dev/null +++ b/docs/Clara.md @@ -0,0 +1,101 @@ +# Clara v1.1.5 +[![Build Status](https://travis-ci.org/catchorg/Clara.svg?branch=master)](https://travis-ci.org/catchorg/Clara) +[![Build status](https://ci.appveyor.com/api/projects/status/github/catchorg/Clara?brach=master&svg=true)](https://ci.appveyor.com/project/catchorg/clara) +[![codecov](https://codecov.io/gh/catchorg/Clara/branch/master/graph/badge.svg)](https://codecov.io/gh/catchorg/Clara) + +----------------------------- + + +A simple to use, composable, command line parser for C++ 11 and beyond. + +Clara is a single-header library. + +To use, just `#include "clara.hpp"` + +A parser for a single option can be created like this: + +```c++ +int width = 0; +// ... +using namespace clara; +auto cli + = Opt( width, "width" ) + ["-w"]["--width"] + ("How wide should it be?"); +``` + +You can use this parser directly like this: + +```c++ +auto result = cli.parse( Args( argc, argv ) ); +if( !result ) { + std::cerr << "Error in command line: " << result.errorMessage() << std::endl; + exit(1); +} + +// Everything was ok, width will have a value if supplied on command line +``` + +Note that exceptions are not used for error handling. + +You can combine parsers by composing with `|`, like this: + +```c++ +int width = 0; +std::string name; +bool doIt = false; +std::string command; +auto cli + = Opt( width, "width" ) + ["-w"]["--width"] + ("How wide should it be?") + | Opt( name, "name" ) + ["-n"]["--name"] + ("By what name should I be known") + | Opt( doIt ) + ["-d"]["--doit"] + ("Do the thing" ) + | Arg( command, "command" ) + ("which command to run"); +``` + +`Opt`s specify options that start with a short dash (`-`) or long dash (`--`). +On Windows forward slashes are also accepted (and automatically interpretted as a short dash). +Options can be argument taking (such as `-w 42`), in which case the `Opt` takes a second argument - a hint, +or they are pure flags (such as `-d`), in which case the `Opt` has only one argument - which must be a boolean. +The option names are provided in one or more sets of square brackets, and a description string can +be provided in parentheses. The first argument to an `Opt` is any variable, local, global member, of any type +that can be converted from a string using `std::ostream`. + +`Arg`s specify arguments that are not tied to options, and so have no square bracket names. They otherwise work just like `Opt`s. + +A, console optimised, usage string can be obtained by inserting the parser into a stream. +The usage string is built from the information supplied and is formatted for the console width. + +As a convenience, the standard help options (`-h`, `--help` and `-?`) can be specified using the `Help` parser, +which just takes a boolean to bind to. + +For more usage please see the unit tests or look at how it is used in the Catch code-base (catch-lib.net). +Fuller documentation will be coming soon. + +Some of the key features: + +- A single header file with no external dependencies (except the std library). +- Define your interface once to get parsing, type conversions and usage strings with no redundancy. +- Composable. Each `Opt` or `Arg` is an independent parser. Combine these to produce a composite parser - this can be done in stages across multiple function calls - or even projects. +- Bind parsers directly to variables that will receive the results of the parse - no intermediate dictionaries to worry about. +- Or can also bind parsers to lambdas for more custom handling. +- Deduces types from bound variables or lambdas and performs type conversions (via `ostream <<`), with error handling, behind the scenes. +- Bind parsers to vectors for args that can have multiple values. +- Uses Result types for error propagation, rather than exceptions (doesn't yet build with exceptions disabled, but that will be coming later) +- Models POSIX standards for short and long opt behaviour. + + +## Old version + +If you used the earlier, v0.x, version of Clara please note that this is a complete rewrite which assumes C++11 and has +a different interface (composability was a big step forward). Conversion between v0.x and v1.x is a fairly simple and mechanical task, but is a bit of manual +work - so don't take this version until you're ready (and, of course, able to use C++11). + +I hope you'll find the new interface an improvement - and this will be built on to offer new features moving forwards. +I don't expect to maintain v0.x any further, but it remains on a branch.