Something I’ve been working on recently is a command line tool [1] to bring clap declarative command line parsing to shell scripts. Unfinished WIP but largely functional.
Rust CLI with Clap
31–40 of 92 posts
Re: Rust CLI with Clap
#32Earlier quoted context omitted.
If all the code was crammed into the std library it'd be fine? Functions need to build on top of simpler functions to be able to abstract problems and tackle them one at a time. There's innate complexity around and without trying to tame it into smaller functions/packages it seems you'll end up in a worse spot.
Not OP, but more code in stdlib does indeed sound better. I'm not against abstraction and re-use. What I don't like is that for every given thing I want to do, there are multiple crates that offer the same functionality, and it can be really fatiguing trying to vet them. And it is truly a rarity to find a crate that is past the 1.0 version milestone. Compare to golang for example. You can get quite far in go without…
I'm not the OP here, but I did write the blog post. I have mixed thoughts on how much should be part of std. I think that what we're seeing is a class of library where we could see a new level introduced to open languages like rust that sits somewhere above std, but is maintained and blessed by a broader group than just the nebulous community. Rust's separation of std from no-std is a good example of tiers that I think we could see evolve. Another example in the same category as clap would be serde and some of the specific serde implementations like serde-yaml that is now in a really painful unmaintained/forked status. Maybe these are things to push for more broadly in the rust community.
Re: Rust CLI with Clap
#33In my opinion, clap is a textbook example of over-engineering for a single metric (UX) at the expense of all other considerations (compilation speed, runtime cost, binary size, auditability, and maintainability). It is an 18kloc command-line parser with an additional 125kloc of dependencies that takes nearly 6 seconds to compile (‘only’ 400ms for an incremental build) and which adds nearly 690KiB to an optimised release binary (‘only’ 430KiB if you strip out most of the sugar that only clap provides).
There are many other command-line parsers to choose from that do all the key things that clap does, with half or less the build cost, and most of them with 30x less binary overhead[0]. argh is under 4kloc. gumdrop is under 2kloc. pico-args is under 700loc. What is the value of that extra 10kloc? A 10% better parser?
I am not saying there is no room for a library like clap—it is, at least, a triumphant clown car of features that can handle practically any edge-case anyone ever thought of—but if I got a nickel every time I spent 15 minutes replacing a trivial use of clap with pico-args and thus reduced the binary size and compile time of some project by at least 80%, I would have at least three nickels.
Just to try to pre-empt arguments like “disk space is cheap”, “compiler time is cheaper than human time”, etc.: there are no golden bullets in engineering, only trade-offs. Why would you default to the biggest, slowest option? This is the “every web site must be able to scale like Facebook” type logic. You don’t even have to do more work to use argh or gumdrop. If clap ends up having some magic feature that no other parser has that you absolutely need, you can switch, but I’ve yet to ever encounter such a thing. Its inertia and popularity carry it forward, but it is perhaps the last choice you should pick for a new project—not the first.
Re: Rust CLI with Clap
#34structopt/Clap's derive magic is one of the first things I miss when I go to write some more-or-less trivial program in a non-Rust language these days. Being able to define all the data for a command line argument in one place (how/where to store it, what the type/valid input is, the association between the name and a variable/field, the documentation for --help...) seems like table stakes but afaict almost every oth…
Not sure if it's on par with Clap, but for Python I don't see enough people talk about SimpleParsing: https://github.com/lebrice/SimpleParsing
It has quirks once you try to do something more complex/advanced, but for most of the simple stuff it's very nice to use.
Re: Rust CLI with Clap
#35In my opinion, clap is a textbook example of over-engineering for a single metric (UX) at the expense of all other considerations (compilation speed, runtime cost, binary size, auditability, and maintainability). It is an 18kloc command-line parser with an additional 125kloc of dependencies that takes nearly 6 seconds to compile (‘only’ 400ms for an incremental build) and which adds nearly 690KiB to an optimised rele…
I am wondering how much of this can be mitigated by carefully designing feature flags, and make default feature set small.
Re: Rust CLI with Clap
#36Earlier quoted context omitted.
Not OP, but more code in stdlib does indeed sound better. I'm not against abstraction and re-use. What I don't like is that for every given thing I want to do, there are multiple crates that offer the same functionality, and it can be really fatiguing trying to vet them. And it is truly a rarity to find a crate that is past the 1.0 version milestone. Compare to golang for example. You can get quite far in go without…
I'm not the OP here, but I did write the blog post. I have mixed thoughts on how much should be part of std. I think that what we're seeing is a class of library where we could see a new level introduced to open languages like rust that sits somewhere above std, but is maintained and blessed by a broader group than just the nebulous community. Rust's separation of std from no-std is a good example of tiers that I thi…
I think Rust's std really wants to be just the runtime. Most language stds are runtime + common utilities and then often there's an extra set of common environment libraries with varying levels of distinction.
Re: Rust CLI with Clap
#37In my opinion, clap is a textbook example of over-engineering for a single metric (UX) at the expense of all other considerations (compilation speed, runtime cost, binary size, auditability, and maintainability). It is an 18kloc command-line parser with an additional 125kloc of dependencies that takes nearly 6 seconds to compile (‘only’ 400ms for an incremental build) and which adds nearly 690KiB to an optimised rele…
According to that link you posted, many of the other argument parsers don't even generate help, only one other offers multiple interfaces, and none of the others are noted as having color or suggested fixes.
These aren't exactly esoteric features, and you're not going to get them for free. I'm happy to pay in space and compile time for clap to gain those features.
This isn't a case of the commandline app needing to be facebook, but rather putting the exponential gains we've made in storage space to good use providing features which should be table stakes at this point.
Re: Rust CLI with Clap
#3810kloc for command line parsing. TEN THOUSAND LINES. pico-args does it in 700 lines and probably handles 99% of real world use cases. compile times go to shit binary size bloats and for some edge case you'll never hit.most CLI tools need what three four flags max, maybe a subcommand or two. you don't need the swiss army knife of argument parsing for that. tried replacing clap with pico-args on three different projects last month. 80% reduction in compile time every single time. binary went from 8mb to 2mb on one of them.the "disk space is cheap" argument's acceptable partially but compile time isn't. developer experience isn't. startup time isn't. memory usage isn't
Re: Rust CLI with Clap
#39In my opinion, clap is a textbook example of over-engineering for a single metric (UX) at the expense of all other considerations (compilation speed, runtime cost, binary size, auditability, and maintainability). It is an 18kloc command-line parser with an additional 125kloc of dependencies that takes nearly 6 seconds to compile (‘only’ 400ms for an incremental build) and which adds nearly 690KiB to an optimised rele…
Hmm isn't optimizing to save 690KiB for an optimised release binary and getting incremental builds to be significantly less than 400ms actually much closer to the after-mentioned "every web site must be able to scale like Facebook” type logic" ?
Re: Rust CLI with Clap
#40In my opinion, clap is a textbook example of over-engineering for a single metric (UX) at the expense of all other considerations (compilation speed, runtime cost, binary size, auditability, and maintainability). It is an 18kloc command-line parser with an additional 125kloc of dependencies that takes nearly 6 seconds to compile (‘only’ 400ms for an incremental build) and which adds nearly 690KiB to an optimised rele…
You’re right that there are only trade-offs in engineering. But the key to evaluating trade-offs is evaluating impact, and how long my dependencies take to compile when I first check out a repo or whether it takes 1ms or 2ms to parse my command line (if we’re even talking about something above microseconds) have no discernible impact for approximately all use-cases. If you’re making some odd CLI tool that has to run on an microcontroller with 1MB of RAM or something, fine, agonize about whether your command line parser is parsimonious enough. Otherwise you’ve abjectly failed to evaluate one of the most important trade-offs in engineering: whether something is even worth your time to think about.