Parameter resolution for Go language (flag)

Flag parameter parsing, I thought it would, the results found today, the original is more powerful than I remember.
Just take a moment to remember.
The first example is a common usage:

Flag Example 1//author:xiong Chuan liang//date:2015-4-10package mainimport ("Flag" "FMT" "OS") var (levelflag = flag.) Int ("Level", 0, "levels")   Bnflag int  ) func init () {flag. Intvar (&bnflag, "bn", 3, "number of copies")  }func Main () {flag. Parse ()      count: = Len (OS. Args)    FMT. PRINTLN ("Total number of parameters:", count)    FMT. PRINTLN ("parameter details:") for    I: = 0; I < count; i++{        FMT. Println (i, ":", OS.) Args[i])    }       fmt. Println ("\ n parameter value:") fmt. Println ("Level:", *levelflag) fmt. Println ("Copies:", Bnflag)}/* run Result: C:\temp\testflag>go run tf2.go-level 3-bn=2 parameters total: 4 parameter details: 0:c:\docume~1\admini~1\ Locals~1\temp\go-build158983983\command-line-arguments\_obj\exe\tf2.exe1:-level2:33:-bn=2 parameter value: Level: 3 copies: 2*/

The second example, you can extend the functionality:

Flag Example 2//author:xiong Chuan liang//date:2015-4-10package mainimport ("Flag" "FMT" "OS" "Time") Var (/* Error handling when parameter parsing error switch f.errorhandling {case Continueonerror:return errcase ExitOnError:os.Exit (2) Paniconerror: Panic (err)} *///flagset = flag. Newflagset (OS. Args[0],flag. Paniconerror) Flagset = flag. Newflagset (OS. Args[0],flag. Exitonerror)//flagset = flag. Newflagset ("Xcl", flag. Exitonerror) Verflag = flagset.string ("ver", "" "," version ") Xtimeflag = Flagset.duration (" Time ", 10*time. Minute, "Time Duration") Addrflag = stringarray{}) Func init () {Flagset.var (&addrflag, "a", "B")}func main () {FMT. PRINTLN ("OS. Args[0]: ", OS. Args[0]) flagset.parse (OS. Args[1:])//flagset.parse (OS. Args[0:]) fmt. Println ("Number of current command line parameter types:", Flagset.nflag ()) for I: = 0; I! = Flagset.narg (); i++ {fmt. Printf ("arg[%d]=%s\n", I, flag. ARG (i))} FMT. Println ("\ n parameter value:") fmt. Println ("ver:", *verflag) fmt. Println ("Xtimeflag:", *xtimeflag) fmt. Println ("Addrflag:", addrflag.string ()) for I,param: = Range flag. Args () {        Fmt. PRINTF ("---#%d:%s\n", I,param)}}type Stringarray []stringfunc (S-*stringarray) string () string {return FMT. Sprint ([]string (*s))}func (S *stringarray) Set (value string) error {*s = append (*s, value) return nil}/* run Result: C:\TEMP\ Testflag>go run Tfs.go-ver 9.0-a ba-a ca-a d2-ver 10.0-time 2m0sos. Args[0]: c:\docume~1\admini~1\locals~1\temp\go-build341936307\command-line-arguments\_obj\exe\ Tfs.exe current command line parameter types: 3 parameter value: Ver:10.0xtimeflag:2m0saddrflag: [BA ca d2]c:\temp\testflag>go run tfs.go-ver 9.0-a ba-a C A-a d2-ver 10.0os. Args[0]: c:\docume~1\admini~1\locals~1\temp\go-build712958211\command-line-arguments\_obj\exe\ Tfs.exe current command line parameter types: 2 parameter value: Ver:10.0xtimeflag:10m0saddrflag: [ba ca d2]--flagset = flag. Newflagset (OS. Args[0],flag. Paniconerror) Results: C:\temp\testflag>go run tfs.go-ver 9.0-a ba-a ca-a d2-ver 10.0-time 2m0s33os. Args[0]: C:\docume~1\admini~1\locals~1\temp\go-build841833143\command-line-arguments\_obj\exe\tfs.exeinvalid Value "2m0s33" for Flag-timE:time:missing unit in duration 2m0s33usage of c:\docume~1\admini~1\locals~1\temp\go-build841833143\ Command-line-arguments\_obj\exe\tfs.exe:-a=[]: B-time=10m0s:time duration-ver= "": Versionpanic:invalid value "2m0s Flag-time:time:missing unit in Duration 2m0s33goroutine 1 [running]:flag. (*flagset). Parse (0x10b18180, 0x10b42008, 0xc, 0xc, 0x0, 0x0) c:/go/src/flag/flag.go:814 +0xeemain.main () C:/TEMP/TESTFL ag/tfs.go:41 +0x163exit status 2--flagset = flag. Newflagset (OS. Args[0],flag. Exitonerror) Results: C:\temp\testflag>go run tfs.go-ver 9.0-a ba-a ca-a d2-ver 10.0-time 2m0s33os. Args[0]: C:\docume~1\admini~1\locals~1\temp\go-build501686683\command-line-arguments\_obj\exe\tfs.exeinvalid Value "2m0s33" for flag-time:time:missing unit in duration 2m0s33usage of C:\DOCUME~1\ADMINI~1\LOCALS~1\TEMP\GO-BUILD50 1686683\command-line-arguments\_obj\exe\tfs.exe:-a=[]: B-time=10m0s:time duration-ver= "": Versionexit status 2*/

The Flagset class allows for more flexible parameter handling.
Among them Newflagset:
Flagset = flag. Newflagset ("Xcl", flag. Exitonerror)
The first parameter of the Newflagset can be arbitrarily fixed. But the second argument determines how the error is handled when a parameter parsing error occurs.

If you want to extend the parameter definition, simply implement the following interface:

Type Value Interface {string () Stringset (string) Error}

As Stringarray in the example. It can be implemented as:
-A ba-a ca-a D2
Addrflag: [BA ca D2]
This effect.
You know, the same:
-ver 9.0-ver 10.0
The final result is that the ver:10.0 is the parameter that only identifies the last time.

The getopt () series function compared to Linux. Flag Packet This approach is still clearer and more straight-minded.

blog:http://blog.csdn.net/xcl168

Parameter resolution for Go language (flag)