Example syntax for mason-rs

command.rs

use mason::generate_builder;

#[generate_builder(CommandBuilder)]
pub struct Command {
    #[builder(entrypoint, into, required)]
    program: String,

    args: Vec<String>,

    cwd: Option<String>,
}

fn main() {
    let cmd = Command::program("echo")
        .args(vec!["Hello", "World!"])
        .build();
}

generated.rs

pub struct Command {
    program: String,
    args: Vec<String>,
    cwd: Option<String>,
}

impl Command {
    pub fn program(program: impl Into<String>) -> CommandBuilderWithProgram {
        CommandBuilderWithProgram {
            program: program.into(),
            optionals: CommandBuilderOptional::default(),
        }
    }
}

#[derive(Default)]
pub struct CommandBuilderOptional {
    args: Option<Vec<String>>,
    cwd: Option<String>,
}

pub struct CommandBuilderWithProgram {
    program: String,
    optionals: CommandBuilderOptional,
}

impl CommandBuilderWithProgram {
    pub fn args(mut self, args: Vec<String>) -> CommandBuilderWithProgram {
        self.optionals.args = Some(args);
        self
    }

    pub fn cwd(mut self, cwd: String) -> CommandBuilderWithProgram {
        self.optionals.cwd = Some(cwd);
        self
    }

    pub fn build(self) -> Command {
        let CommandBuilderWithProgram { program, optionals } = self;
        let CommandBuilderOptional { args, cwd } = optionals;
        Command {
            program: program,
            args: args.unwrap_or_else(Default::default),
            cwd: cwd,
        }
    }
}

fn main() {
    let cmd = Command::program("echo")
        .args(
            vec!["Hello", "World!"]
                .into_iter()
                .map(String::from)
                .collect(),
        )
        .build();
}