Negative int value gets parsed as a new flag.

[mcourteaux]

With an int-valued flag, one cannot enter a negative integer as parameter, because it gets parsed as new flag.

Eg:

# Does work:
./foo --number 42 --file test.txt
# Doesn't work
./foo --number -1 --file test.txt

[TeXitoi]

Should work

./foo --number=-1 --file test.txt

You may also be interested by https://docs.rs/clap/2.32.0/clap/enum.AppSettings.html#variant.AllowLeadingHyphen and https://docs.rs/clap/2.32.0/clap/enum.AppSettings.html#variant.AllowNegativeNumbers

See https://github.com/TeXitoi/structopt/blob/master/examples/raw_attributes.rs for an example using AppSettings.

I'll add an example later.

Does it fix your problem?

[mcourteaux]

Oh, yep it does! I'm guessing Google hasn't crawled these docs yet... Thanks!

…

On 6 Aug 2018, at 14:21, Guillaume P. ***@***.***> wrote: Should work ./foo --number=-1 --file test.txt You may also be interested by https://docs.rs/clap/2.32.0/clap/enum.AppSettings.html#variant.AllowLeadingHyphen <https://docs.rs/clap/2.32.0/clap/enum.AppSettings.html#variant.AllowLeadingHyphen> and https://docs.rs/clap/2.32.0/clap/enum.AppSettings.html#variant.AllowNegativeNumbers <https://docs.rs/clap/2.32.0/clap/enum.AppSettings.html#variant.AllowNegativeNumbers> See https://github.com/TeXitoi/structopt/blob/master/examples/raw_attributes.rs <https://github.com/TeXitoi/structopt/blob/master/examples/raw_attributes.rs> for an example using AppSettings. I'll add an example later. Does it fix your problem? — You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub <#129 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAzk1OWR9ew2bSBdkcgrmaic08XWwXJ_ks5uODTbgaJpZM4VwRes>.

[1Dragoon]

I couldn't find any examples for how to do this without using the equals sign (TeXitoi's third link has a 404 and I can't find it in the examples dir, or maybe I'm not looking hard enough?) but for anybody else who lands here from google, I figured it out and it works like this:

#[derive(Debug, StructOpt)]
#[structopt(about = "My little program.", settings = &[AppSettings::AllowNegativeNumbers])]
struct Opt {
    /// My parameter that accepts negative numbers
    param: i32,
}

you can then run it like so:

./myprogram --param -20

[cdstanford]

TeXitoi's workaround also doesn't apply for multiple int arguments, like:

#[derive(StructOpt)]
#[structopt(about = "CLI accepting a list of integers.")]
struct VecInt {
    #[structopt(short, required = true)]
    ints: Vec<isize>,
},

I haven't figured out how to escape the ints on the command line yet.

[cdstanford]

There's an allow_hyphen_values(true) option discussed here, but doesn't seem to work for my use case. In an example with multiple Vec<isize> arguments, all arguments past the first one no longer work because the hyphens are ignored starting from where the Vec starts parsing.

I would be happy with a solution where I escape the negative values somewhow.

[epage]

@cdstanford can you provide an example command line that fails? I want to make sure I'm finding a solution to your problem and not my guess as to your problem.

[cdstanford]

Absolutely -- apologies for not providing a full example before. Here's a CLI that tries to add up lists of integers:

use structopt::StructOpt;

#[derive(StructOpt)]
#[structopt(about = "Sum one or more lists of ints.")]
enum Cli {
    SumOne {
        #[structopt(short, required = true, allow_hyphen_values(true))]
        a: Vec<isize>,
    },
    SumTwo {
        #[structopt(short, required = true, allow_hyphen_values(true))]
        a: Vec<isize>,
        #[structopt(short, required = true, allow_hyphen_values(true))]
        b: Vec<isize>,
    },
}

fn main() {
    fn sum(l: &[isize]) -> isize {
        l.iter().sum()
    }
    match Cli::from_args() {
        Cli::SumOne { a } => println!("{}", sum(&a)),
        Cli::SumTwo { a, b } => println!("{} {}", sum(&a), sum(&b)),
    }
}

The SumOne command works: cargo run -- sum-one -a 1 2 -3 gives 0. But the SumTwo command is not able to parse the -b argument. Error message for cargo run -- sum-two -a 1 2 3 -b 1 2 -3:

error: The following required arguments were not provided:
    -b <b>...

USAGE:
    structopt sum-two -a <a>... -b <b>...

[cdstanford]

P.S. Let me know if I should rase a new issue for this case, it's diverged a bit from the original post here.

[epage]

If you add this to your Cargo.toml:

clap = { version = "2", features = ["debug"] }

You can see whats going wrong under the hood

DEBUG:clap:Parser::get_matches_with: Begin parsing '"3"' ([51])      
DEBUG:clap:Parser::is_new_arg:"3":Opt("a")                  
DEBUG:clap:Parser::is_new_arg: arg_allows_tac=true
DEBUG:clap:Parser::is_new_arg: probably value
DEBUG:clap:Parser::is_new_arg: starts_new_arg=false
DEBUG:clap:Parser::add_val_to_arg; arg=a, val="3" 
DEBUG:clap:Parser::add_val_to_arg; trailing_vals=false, DontDelimTrailingVals=false
DEBUG:clap:Parser::add_single_val_to_arg;            
DEBUG:clap:Parser::add_single_val_to_arg: adding val..."3" 
DEBUG:clap:Parser::groups_for_arg: name=a              
DEBUG:clap:Parser::groups_for_arg: No groups defined                                                                                               
DEBUG:clap:ArgMatcher::needs_more_vals: o=a

DEBUG:clap:Parser::get_matches_with: Begin parsing '"-b"' ([45, 98])
DEBUG:clap:Parser::is_new_arg:"-b":Opt("a")
DEBUG:clap:Parser::is_new_arg: arg_allows_tac=true
DEBUG:clap:Parser::is_new_arg: - found
DEBUG:clap:Parser::is_new_arg: starts_new_arg=false                                                                                                
DEBUG:clap:Parser::add_val_to_arg; arg=a, val="-b"               
DEBUG:clap:Parser::add_val_to_arg; trailing_vals=false, DontDelimTrailingVals=false
DEBUG:clap:Parser::add_single_val_to_arg;                        
DEBUG:clap:Parser::add_single_val_to_arg: adding val..."-b"
DEBUG:clap:Parser::groups_for_arg: name=a                    
DEBUG:clap:Parser::groups_for_arg: No groups defined
DEBUG:clap:ArgMatcher::needs_more_vals: o=a    

DEBUG:clap:Parser::get_matches_with: Begin parsing '"1"' ([49])
DEBUG:clap:Parser::is_new_arg:"1":Opt("a")          
DEBUG:clap:Parser::is_new_arg: arg_allows_tac=true    
DEBUG:clap:Parser::is_new_arg: probably value           
DEBUG:clap:Parser::is_new_arg: starts_new_arg=false
DEBUG:clap:Parser::add_val_to_arg; arg=a, val="1"

• Newlines added to make it more clear
• Before and after case provided for contrast

-b starts with a hyphen, so clap is picking that up as an argument for -a. The fact that a only takes isize doesn't come into the picture until later, when validating the values associated with each argument.

What I find strange is AllowNegativeNumbers is meant to address this but isn't working

use structopt::StructOpt;

#[derive(StructOpt)]
#[structopt(about = "Sum one or more lists of ints.")]
#[structopt(settings = &[structopt::clap::AppSettings::AllowNegativeNumbers])]
enum Cli {
    SumOne {
        #[structopt(short, required = true)]
        a: Vec<isize>,
    },
    SumTwo {
        #[structopt(short, required = true)]
        a: Vec<isize>,
        #[structopt(short, required = true)]
        b: Vec<isize>,
    },
}

fn main() {
    fn sum(l: &[isize]) -> isize {
        l.iter().sum()
    }
    match Cli::from_args() {
        Cli::SumOne { a } => println!("{}", sum(&a)),
        Cli::SumTwo { a, b } => println!("{} {}", sum(&a), sum(&b)),
    }
}

gives

❯ cargo run -- sum-one -a 1 2 -3
    Finished dev [unoptimized + debuginfo] target(s) in 0.01s
     Running `target/debug/test-clap sum-one -a 1 2 -3`
error: Found argument '-3' which wasn't expected, or isn't valid in this context

USAGE:
    test-clap sum-one -a <a>...

For more information try --help

[epage]

Nevermind, I made the common mistake of forgetting global_setting. We need to fix that in clap.

This works:

use structopt::StructOpt;

#[derive(StructOpt)]
#[structopt(about = "Sum one or more lists of ints.")]
#[structopt(global_setting = structopt::clap::AppSettings::AllowNegativeNumbers)]
enum Cli {
    SumOne {
        #[structopt(short, required = true)]
        a: Vec<isize>,
    },
    SumTwo {
        #[structopt(short, required = true)]
        a: Vec<isize>,
        #[structopt(short, required = true)]
        b: Vec<isize>,
    },
}

fn main() {
    fn sum(l: &[isize]) -> isize {
        l.iter().sum()
    }
    match Cli::from_args() {
        Cli::SumOne { a } => println!("{}", sum(&a)),
        Cli::SumTwo { a, b } => println!("{} {}", sum(&a), sum(&b)),
    }
}
``

[epage]

I created clap-rs/clap#3028 about the API trap of setting vs global_setting

[cdstanford]

Excellent!! Thanks so much for the help!