arguments.md

Arguments

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Targets can accept typed arguments from the command line.

Supported Types

• string
• int
• bool
• float64
• time.Duration

Defining Arguments

Add parameters after the optional context:

func Greet(name string, times int) error {
    for i := 0; i < times; i++ {
        fmt.Printf("Hello, %s!\n", name)
    }
    return nil
}

Invoking with Arguments

Pass arguments positionally after the target name:

stave greet Alice 3

Output:

Hello, Alice!
Hello, Alice!
Hello, Alice!

Type Parsing

Arguments are parsed according to their declared type:

Type	Example Input	Parsed Value
string	hello	"hello"
int	42	42
bool	true, false, 1, 0	true, false
float64	3.14	3.14
time.Duration	5m30s	5*time.Minute + 30*time.Second

Arguments with Context

Context and arguments can be combined:

func Deploy(ctx context.Context, env string, dryRun bool) error {
    if dryRun {
        fmt.Printf("Would deploy to %s\n", env)
        return nil
    }
    // actual deployment
    return nil
}

stave deploy production false

Arguments in Dependencies

Use st.F to pass arguments when declaring dependencies:

func Deploy(env string) error {
    fmt.Printf("Deploying to %s\n", env)
    return nil
}

func DeployAll() {
    st.Deps(
        st.F(Deploy, "staging"),
        st.F(Deploy, "production"),
    )
}

Each st.F call with distinct arguments is a separate dependency. Both run (in parallel by default), each exactly once.

Argument Errors

Missing or malformed arguments cause Stave to exit with code 2:

stave greet Alice
# Error: not enough arguments for target "Greet", expected 2, got 1

stave greet Alice notanumber
# Error: can't convert argument "notanumber" to int

Viewing Argument Requirements

Use stave -i to see a target's arguments:

stave -i greet

Output:

Usage:

    stave greet <name> <times>

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See Also

• Targets - Defining targets
• Dependencies - Using st.F with arguments
• Home