Cobra Migration Guide¶

Mamba mirrors cobra's API. This guide shows side-by-side equivalents.

Command definition¶

Cobra (Go)Mamba (Zig)

var rootCmd = &cobra.Command{
    Use:   "myapp",
    Short: "A brief description",
    Long:  "A longer description",
    Run: func(cmd *cobra.Command, args []string) {
        fmt.Println("Hello!")
    },
}

var root = mamba.Command.init(.{
    .name = "myapp",
    .short = "A brief description",
    .long = "A longer description",
    .run = &struct {
        fn run(cmd: *mamba.Command, args: []const []const u8) !void {
            _ = args;
            cmd.writeOut("Hello!\n");
        }
    }.run,
});

Flags¶

Cobra (Go)Mamba (Zig)

rootCmd.Flags().StringP("config", "c", "app.yaml", "config file")
rootCmd.Flags().IntP("port", "p", 8080, "server port")
rootCmd.Flags().BoolP("verbose", "v", false, "verbose output")

.flags = &.{
    mamba.Flag.string("config", 'c', "config file", "app.yaml"),
    mamba.Flag.int("port", 'p', "server port", 8080),
    mamba.Flag.boolean("verbose", 'v', "verbose output", false),
},

Reading flags¶

Cobra (Go)Mamba (Zig)

config, _ := cmd.Flags().GetString("config")
port, _ := cmd.Flags().GetInt("port")
verbose, _ := cmd.Flags().GetBool("verbose")

const config = cmd.getFlag([]const u8, "config");
const port = cmd.getFlag(i64, "port");
const verbose = cmd.getFlag(bool, "verbose");

Subcommands¶

Cobra (Go)Mamba (Zig)

rootCmd.AddCommand(serveCmd)
rootCmd.AddCommand(migrateCmd)
rootCmd.Execute()

root.addCommand(&serve);
root.addCommand(&migrate);
try root.execute();

Persistent flags¶

Cobra (Go)Mamba (Zig)

rootCmd.PersistentFlags().BoolP("verbose", "v", false, "verbose output")

.persistent_flags = &.{
    mamba.Flag.boolean("verbose", 'v', "verbose output", false),
},

Hooks¶

Cobra (Go)Mamba (Zig)

&cobra.Command{
    PersistentPreRun:  func(cmd *cobra.Command, args []string) { ... },
    PreRun:            func(cmd *cobra.Command, args []string) { ... },
    Run:               func(cmd *cobra.Command, args []string) { ... },
    PostRun:           func(cmd *cobra.Command, args []string) { ... },
    PersistentPostRun: func(cmd *cobra.Command, args []string) { ... },
}

.persistent_pre_run = &persistentPreRun,
.pre_run = &preRun,
.run = &mainRun,
.post_run = &postRun,
.persistent_post_run = &persistentPostRun,

Argument validation¶

Cobra (Go)Mamba (Zig)

Args: cobra.ExactArgs(2),
Args: cobra.MinimumNArgs(1),
Args: cobra.RangeArgs(1, 3),
Args: cobra.NoArgs,

.args = mamba.args.exactArgs(2),
.args = mamba.args.minimumNArgs(1),
.args = mamba.args.rangeArgs(1, 3),
.args = mamba.args.noArgs,

Key differences¶

Aspect	Cobra	Mamba
Memory	Heap-allocated	Stack-allocated, zero alloc
Flag definition	Runtime method calls	Comptime struct literals
Error handling	Returns `error`	Returns Zig `error` union
Output	`fmt.Println` / `cmd.Println`	`cmd.writeOut()`
Int type	`int` (platform-sized)	`i64`
Generics	Interface-based	`comptime T: type`