taldir

Directory service to resolve wallet mailboxes by messenger addresses
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README.md (2021B)

      1 # rsc.io/getopt
      2 
      3 [For full package documentation, see [https://godoc.org/rsc.io/getopt](https://godoc.org/rsc.io/getopt).]
      4 
      5     package getopt // import "rsc.io/getopt"
      6 
      7 Package getopt parses command lines using [_getopt_(3)](http://man7.org/linux/man-pages/man3/getopt.3.html) syntax. It is a
      8 replacement for `flag.Parse` but still expects flags themselves to be defined
      9 in package flag.
     10 
     11 Flags defined with one-letter names are available as short flags (invoked
     12 using one dash, as in `-x`) and all flags are available as long flags (invoked
     13 using two dashes, as in `--x` or `--xylophone`).
     14 
     15 To use, define flags as usual with [package flag](https://godoc.org/flag). Then introduce any aliases
     16 by calling `getopt.Alias`:
     17 
     18     getopt.Alias("v", "verbose")
     19 
     20 Or call `getopt.Aliases` to define a list of aliases:
     21 
     22     getopt.Aliases(
     23     	"v", "verbose",
     24     	"x", "xylophone",
     25     )
     26 
     27 One name in each pair must already be defined in package flag (so either
     28 "v" or "verbose", and also either "x" or "xylophone").
     29 
     30 Then parse the command-line:
     31 
     32     getopt.Parse()
     33 
     34 If it encounters an error, `Parse` calls `flag.Usage` and then exits the
     35 program.
     36 
     37 When writing a custom `flag.Usage` function, call `getopt.PrintDefaults` instead
     38 of `flag.PrintDefaults` to get a usage message that includes the
     39 names of aliases in flag descriptions.
     40 
     41 At initialization time, package getopt installs a new `flag.Usage` that is the same
     42 as the default `flag.Usage` except that it calls `getopt.PrintDefaults` instead
     43 of `flag.PrintDefaults`.
     44 
     45 This package also defines a `FlagSet` wrapping the standard `flag.FlagSet`.
     46 
     47 ## Caveat
     48 
     49 In general Go flag parsing is preferred for new programs, because it is not
     50 as pedantic about the number of dashes used to invoke a flag (you can write
     51 `-verbose` or `--verbose` and the program does not care). This package is meant
     52 to be used in situations where, for legacy reasons, it is important to use
     53 exactly _getopt_(3) syntax, such as when rewriting in Go an existing tool that
     54 already uses _getopt_(3).