Yes, it has been almost two years since I made the first commit to cpp-argparse repository. Back then, it was still tracked in Mercurial and hosted on BitBucket, which I soon changed to Git and GitHub combo.
Motivation
Ever since I started programming in C++ I was creating some small command-line utilities. All those programs had crippled support for argument parsing, reduced to the bare minimum which was implementable without too much effort.
All the time I was wondering why didn’t the standard library offer anything that would make parsing the arguments easier.
New versions of the language were released (C++11/14/17) which offered a lot of
improvements, but none of those helped with the mundane task of converting the
old argc and argv duo into something more useful.
Over the years I mostly switched to using Python to write my small utilities.
I started using argparse and with every utility I wrote, in which parsing args
was a breeze, I liked it more and more.
At some point I decided I want the same kind of experience when writing code in C++.
Alternatives
I know that there are some third party libraries for parsing command line.
There is Clara that started as part of the Catch unit testing framework, docopt.cpp, or Boost.Program_options just to name a few.
Each has its own style and approach to creating the parsers. And each has its own shortcomings.
The start
Since the beginning I knew I wanted as much a hassle-free library as possible.
In C++ world, this mostly translates to header-only and no external
dependencies. I was pretty sure I would need an optional type and did not want
to code it myself, so I chose to rely on C++17, which amongst other goodies
provides std::optional.
I wanted to follow TDD approach as rigorously as I could. I decided to use doctest unit testing framework - a departure from Catch which I often used in my previous projects.
I quickly switched to CMake as I wanted to build (at least) on Linux and Windows, and did not feel like creating separate projects.
Expectations
I set my expectations low. I did not want to aim at implementing the whole functionality and then fail to deliver. Instead, I wanted to include the bare minimum that still would be useful.
I did not create a feature list nor a roadmap, but I realised that handling of positional and optional arguments, support for various argument types, automatic help generation, and error handling all were a must. Everything else would be an icing on the cake for me.
The outcome
As of version 0.8.3, which is the latest release, cpp-argparse supports more
functionality that I hoped for (more in the
previous post).
Still, there is more to come and 0.8.3 is definitely not the last release :-)
Looking back
cpp-argparse did prove to be fun to work on and sucked me in almost
completely. During those two years of intermittent development I had lots of fun
and I learned quite a lot. But more on this in the next installment.