Arguments¶

Positional arguments are everything on the command line that isn't a flag. Mamba provides validators to enforce argument count and content.

Validators¶

Set the .args field on your command:

var cmd = mamba.Command.init(.{
    .name = "copy",
    .args = mamba.args.exactArgs(2),  // requires exactly 2 args
    .run = &copyRun,
});

Built-in validators¶

Validator	Description
`args.noArgs`	Accept no positional arguments
`args.arbitraryArgs`	Accept any number of arguments
`args.exactArgs(n)`	Require exactly `n` arguments
`args.minimumNArgs(n)`	Require at least `n` arguments
`args.maximumNArgs(n)`	Require at most `n` arguments
`args.rangeArgs(min, max)`	Require between `min` and `max` arguments
`args.onlyValidArgs`	Only accept arguments listed in `.valid_args`
`args.matchAll(validators)`	All validators must pass

Examples¶

// File copy: exactly source and destination
.args = mamba.args.exactArgs(2),

// Grep: at least a pattern
.args = mamba.args.minimumNArgs(1),

// Optional output file
.args = mamba.args.rangeArgs(1, 2),

// Only specific values
.valid_args = &.{ "start", "stop", "restart" },
.args = mamba.args.onlyValidArgs,

// Combine: at least 1 arg, and only valid values
.args = mamba.args.matchAll(&.{
    mamba.args.minimumNArgs(1),
    mamba.args.onlyValidArgs,
}),

Reading arguments¶

Positional arguments are the second parameter of the run function:

fn copyRun(cmd: *mamba.Command, positional: []const []const u8) !void {
    const source = positional[0];
    const dest = positional[1];
    cmd.writeOut("Copying ");
    cmd.writeOut(source);
    cmd.writeOut(" to ");
    cmd.writeOut(dest);
    cmd.writeOut("\n");
}

Error messages¶

When validation fails, mamba prints a cobra-style error:

Error: accepts 2 arg(s), received 1