Struct Tag Reference

Tag Format

The goopt tag format uses semicolon-separated key:value pairs. All options are defined under the goopt namespace:

type Config struct {
    Output string `goopt:"name:output;desc:Output file;required:true"`
}

Available Tags

Tag	Description	Example
kind	Specifies if it’s a flag or command (default: flag)	kind:flag|command
name	Long name for the flag/command	name:output
short	Short name (single-char for POSIX mode)	short:o
desc	Description shown in help	desc:Output file
type	Flag type	type:single|standalone|chained|file
required	Whether flag is required	required:true|false
default	Default value	default:stdout
secure	For password input	secure:true|false
prompt	Prompt text for secure input	prompt:Password:
capacity	Slice capacity for nested structs	capacity:3
pos	Position requirements	pos:0
accepted	Accepted values/patterns	accepted:{pattern:json|yaml,desc:Format}
depends	Flag dependencies	depends:{flag:output,values:[json]}

Position Tag

The pos tag allows specifying position requirements for arguments:

type Config struct {
    // Must be first argument
    Source string `goopt:"name:source;pos:0"`
        // Second argument from start
    Profile string `goopt:"name:profile;pos:1"`
    // Must be last argument
    Dest string `goopt:"name:dest;pos:2"`
    
}

Complex Tag Examples

Multiple Accepted Values

type Config struct {
    Format string `goopt:"name:format;accepted:{pattern:json|yaml,desc:Format},{pattern:text|binary,desc:Type}"`
}

Multiple Dependencies

type Config struct {
    Compress bool `goopt:"name:compress;depends:{flag:format,values:[json]},{flag:output,values:[file]}"`
}