diff options
Diffstat (limited to 'parse.go')
| -rw-r--r-- | parse.go | 55 |
1 files changed, 41 insertions, 14 deletions
@@ -83,18 +83,7 @@ func MustParse(dest ...interface{}) *Parser { return nil // just in case osExit was monkey-patched } - err = p.Parse(flags()) - switch { - case err == ErrHelp: - p.writeHelpForSubcommand(stdout, p.lastCmd) - osExit(0) - case err == ErrVersion: - fmt.Fprintln(stdout, p.version) - osExit(0) - case err != nil: - p.failWithSubcommand(err.Error(), p.lastCmd) - } - + p.MustParse(flags()) return p } @@ -122,6 +111,10 @@ type Config struct { // IgnoreEnv instructs the library not to read environment variables IgnoreEnv bool + + // IgnoreDefault instructs the library not to reset the variables to the + // default values, including pointers to sub commands + IgnoreDefault bool } // Parser represents a set of command line options with destination values @@ -131,6 +124,7 @@ type Parser struct { config Config version string description string + epilogue string // the following field changes during processing of command line arguments lastCmd *command @@ -152,6 +146,14 @@ type Described interface { Description() string } +// Epilogued is the interface that the destination struct should implement to +// add an epilogue string at the bottom of the help message. +type Epilogued interface { + // Epilogue returns the string that will be printed on a line by itself + // at the end of the help message. + Epilogue() string +} + // walkFields calls a function for each field of a struct, recursively expanding struct fields. func walkFields(t reflect.Type, visit func(field reflect.StructField, owner reflect.Type) bool) { walkFieldsImpl(t, visit, nil) @@ -246,6 +248,9 @@ func NewParser(config Config, dests ...interface{}) (*Parser, error) { if dest, ok := dest.(Described); ok { p.description = dest.Description() } + if dest, ok := dest.(Epilogued); ok { + p.epilogue = dest.Epilogue() + } } return &p, nil @@ -470,6 +475,20 @@ func (p *Parser) Parse(args []string) error { return err } +func (p *Parser) MustParse(args []string) { + err := p.Parse(args) + switch { + case err == ErrHelp: + p.writeHelpForSubcommand(stdout, p.lastCmd) + osExit(0) + case err == ErrVersion: + fmt.Fprintln(stdout, p.version) + osExit(0) + case err != nil: + p.failWithSubcommand(err.Error(), p.lastCmd) + } +} + // process environment vars for the given arguments func (p *Parser) captureEnvVars(specs []*spec, wasPresent map[*spec]bool) error { for _, spec := range specs { @@ -564,7 +583,9 @@ func (p *Parser) process(args []string) error { // instantiate the field to point to a new struct v := p.val(subcmd.dest) - v.Set(reflect.New(v.Type().Elem())) // we already checked that all subcommands are struct pointers + if v.IsNil() { + v.Set(reflect.New(v.Type().Elem())) // we already checked that all subcommands are struct pointers + } // add the new options to the set of allowed options specs = append(specs, subcmd.specs...) @@ -696,7 +717,13 @@ func (p *Parser) process(args []string) error { } return errors.New(msg) } - if spec.defaultValue.IsValid() { + + if spec.defaultValue.IsValid() && !p.config.IgnoreDefault { + // One issue here is that if the user now modifies the value then + // the default value stored in the spec will be corrupted. There + // is no general way to "deep-copy" values in Go, and we still + // support the old-style method for specifying defaults as + // Go values assigned directly to the struct field, so we are stuck. p.val(spec.dest).Set(spec.defaultValue) } } |