command-line-rust VS clap-rs

You absolutely must write programs, preferably using tests to ensure you are creating correct and reproducible code. May I suggest starting with my book, Command-Line Rust (O'Reilly, 2022). All the code/data/tests are in https://github.com/kyclark/command-line-rust Note that there are branches showing how to use the 4.x version of clap (command-line argument parser) rather than the 2.33 that was current when the book was published.

I think the best way to start learning a programming language is to write lots of small programs that you probably already know. Rust is a perfect command-line language, so I think it makes sense to start by implementing simple programs like "head" and "grep." I also think one should always learn to write and run tests, so I present my GitHub repo of inputs and tests you might like to use to write 14 such standard Unix command-line utilities: https://github.com/kyclark/command-line-rust If you want guidance on the language, I wrote a book called Command-Line Rust (O'Reilly, 2022) that explains all this code. One caveat is that the "clap" (command-line argument parser) module was at 2.33 when I published but is now v4, so you should look at the appropriate branches for versions of the programs that use the "builder" and "derive" patterns for that module. Or just use any old command-line parser you like as there's no requirement to use "clap." Best of luck to you!

You must write programs in a language in order to learn it. I also firmly believe that learning how to write and run tests is critical to learning any language. I wrote Command-Line Rust (O'Reilly, 2022) for the beginner (in Rust, at least) and with a focus on writing and testing small programs from very simple "Hello, world!" and getting increasingly more complex. You can look at https://github.com/kyclark/command-line-rust for the code/inputs/tests. Best of luck!

Code for the above book

I'm the author of Command-Line Rust (O'Reilly, 2022), which I wrote to introduce the language slowly to beginners by writing and testing short, focused programs. You can look over the code/tests/data at https://github.com/kyclark/command-line-rust. Note that there are branches that show the same programs using a more recent version of the "clap" crate.

I wrote Command-Line Rust (O'Reilly, 2022) to guide beginners in the language. You are challenged to write small functions and programs using tests to verify that everything is correct. You can look over the code and tests at https://github.com/kyclark/command-line-rust. Best of luck in your journey!

Here are the example programs from my book, Command-Line Rust (O'Reilly, 2022), along with the input files and tests: https://github.com/kyclark/command-line-rust

I like to suggest that students write programs they already know (or at least understand). For instance, you probably understand that head shows the first few lines of a text file, and you probably can already implement some version of that in one or two languages you know. Try that in Rust. I wrote 14 BSD/GNU command-line utilities in Rust for learning purposes. I wouldn't consider these high-performance/production programs as they are tailored to learning the language. I also stress how to test programs, so there are tests and inputs you can use to verify your programs match the output of the original programs (or you can modify these to suit your own tastes for how you would like them to work). https://github.com/kyclark/command-line-rust

Here are some more examples you may or may not find useful: https://github.com/kyclark/command-line-rust I tend to have a main() that calls a library's run() function that returns a Result and then exit with a nonzero code and error message on a failure.

Seems unfair. Version 4 was almost 3 years ago and and I can't recall any issue in that time.

Major versions have good quality migration guides. If only all libraries were developed with such professionalism.

https://github.com/clap-rs/clap/blob/v4.5.0/CHANGELOG.md

Rust’s modularity and ergonomic design, combined with the powerful clap crate, allowed us to build Spin’s highly extensible Command Line Interface (CLI).

Clap: Command-Line Argument Parser for Rust

CLI parameters can be easily added to our application using the clap crate.

> To the extent there is an exception, testing-only code may be. Testing-only code has very different constraints than production code anyhow. Even then, though, I still find that refactoring problem arises, and test code needs to be refactorable too.

For me, I avoid defining anything within a function except when that thing being defined is what is being tested in a test, e.g. https://github.com/clap-rs/clap/blob/87647d268c8c27e3298b2c0...

We will be using the library for Clap - A simple-to-use, efficient, and full-featured library for parsing command line arguments and subcommands.

I recently came across this question (and associated answer) on the clap repository. The answer given is a good one. But I wanted to expand with my own findings and practices, which spurred the motivation for this post.

We can also use tuple-like struct syntax and named-field struct syntax for enum variants within our enum; this is because unlike in other OOP languages, Rust enums are actually sum types. You can read more about how powerful Rust enums are in another article we wrote here. You can have optional arguments by simply wrapping the types in Option, but if you want to add a flag to a command you can use bool, since clap recognises that flags are either there or not there. Let's have a look at what this might look like:

I began by developing a wrapper for the CurseForge API, which turned out to be a lengthy and challenging process but constituted the bulk of the work. Next, I coded the CLI, which was relatively straightforward. Instead of using the clap crate, a Rust tool for generating CLIs, I opted for the following line of code: