《Golang 工具 go doc 使用透析》

➜  ~ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="/Users/jordy/Library/Caches/go-build"
GOENV="/Users/jordy/Library/Application Support/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="darwin"
GONOPROXY="git.xxx.com"
GONOSUMDB="git.xxx.com"
GOOS="darwin"
GOPATH="/Users/jordy/go"
GOPRIVATE="git.xxx.com"
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/local/Cellar/go/1.13.8/libexec"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/local/Cellar/go/1.13.8/libexec/pkg/tool/darwin_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/var/folders/66/vyyywgr55f1b7shr11s8hg5w0000gn/T/go-build695446787=/tmp/go-build -gno-record-gcc-switches -fno-common"

➜  ~ go help doc
usage: go doc [-u] [-c] [package|[package.]symbol[.methodOrField]]

Doc prints the documentation comments associated with the item identified by its
arguments (a package, const, func, type, var, method, or struct field)
followed by a one-line summary of each of the first-level items "under"
that item (package-level declarations for a package, methods for a type,
etc.).

➜  ~ go doc url
package url // import "net/url"
Package url parses URLs and implements query escaping.
func PathEscape(s string) string
func PathUnescape(s string) (string, error)
func QueryEscape(s string) string
func QueryUnescape(s string) (string, error)
type Error struct{ ... }
type EscapeError string
type InvalidHostError string
type URL struct{ ... }
    func Parse(rawurl string) (*URL, error)
    func ParseRequestURI(rawurl string) (*URL, error)
type Userinfo struct{ ... }
    func User(username string) *Userinfo
    func UserPassword(username, password string) *Userinfo
type Values map[string][]string
    func ParseQuery(query string) (Values, error)

go doc url.URL
package url // import "net/url"
type URL struct {
	Scheme     string
	Opaque     string    // encoded opaque data
	User       *Userinfo // username and password information
	Host       string    // host or host:port
	Path       string    // path (relative paths may omit leading slash)
	RawPath    string    // encoded path hint (see EscapedPath method)
	ForceQuery bool      // append a query ('?') even if RawQuery is empty
	RawQuery   string    // encoded query values, without '?'
	Fragment   string    // fragment for references, without '#'
}
    A URL represents a parsed URL (technically, a URI reference).
    The general form represented is:
        [scheme:][//[userinfo@]host][/]path[?query][#fragment]
    URLs that do not start with a slash after the scheme are interpreted as:
        scheme:opaque[?query][#fragment]
    Note that the Path field is stored in decoded form: /%47%6f%2f becomes /Go/.
    A consequence is that it is impossible to tell which slashes in the Path
    were slashes in the raw URL and which were %2f. This distinction is rarely
    important, but when it is, the code should use RawPath, an optional field
    which only gets set if the default encoding is different from Path.
    URL's String method uses the EscapedPath method to obtain the path. See the
    EscapedPath method for more details.
func Parse(rawurl string) (*URL, error)
func ParseRequestURI(rawurl string) (*URL, error)
func (u *URL) EscapedPath() string
func (u *URL) Hostname() string
func (u *URL) IsAbs() bool
func (u *URL) MarshalBinary() (text []byte, err error)
func (u *URL) Parse(ref string) (*URL, error)
func (u *URL) Port() string
func (u *URL) Query() Values
func (u *URL) RequestURI() string
func (u *URL) ResolveReference(ref *URL) *URL
func (u *URL) String() string
func (u *URL) UnmarshalBinary(text []byte) error

➜  ~ go doc url.URL.EscapedPath
package url // import "net/url"

func (u *URL) EscapedPath() string
    EscapedPath returns the escaped form of u.Path. In general there are
    multiple possible escaped forms of any path. EscapedPath returns u.RawPath
    when it is a valid escaping of u.Path. Otherwise EscapedPath ignores
    u.RawPath and computes an escaped form on its own. The String and RequestURI
    methods use EscapedPath to construct their results. In general, code should
    call EscapedPath instead of reading u.RawPath directly.

➜  ~ godoc --help
usage: godoc -http=localhost:6060
  -analysis string
    	comma-separated list of analyses to perform (supported: type, pointer). See http://golang.org/lib/godoc/analysis/help.html
  -goroot string
    	Go root directory (default "/usr/local/Cellar/go/1.13.8/libexec")
  -http string
    	HTTP service address (default "localhost:6060")
  -index
    	enable search index
  -index_files string
    	glob pattern specifying index files; if not empty, the index is read from these files in sorted order
  -index_interval duration
    	interval of indexing; 0 for default (5m), negative to only index once at startup
  -index_throttle float
    	index throttle value; 0.0 = no time allocated, 1.0 = full throttle (default 0.75)
  -links
    	link identifiers to their declarations (default true)
  -maxresults int
    	maximum number of full text search results shown (default 10000)
  -notes string
    	regular expression matching note markers to show (default "BUG")
  -play
    	enable playground
  -templates string
    	load templates/JS/CSS from disk in this directory
  -timestamps
    	show timestamps with directory listings
  -url string
    	print HTML for named URL
  -v	verbose mode
  -write_index
    	write index to a file; the file name must be specified with -index_files
  -zip string
    	zip file providing the file system to serve; disabled if empty

godoc -http :6060

http://localhost:6060/pkg/net/url/#example_URL_EscapedPath

➜ pwd
/usr/local/Cellar/go/1.13.8/libexec
➜ tree -L 1
.
├── CONTRIBUTING.md
├── CONTRIBUTORS
├── PATENTS
├── SECURITY.md
├── VERSION
├── api
├── bin
├── doc
├── favicon.ico
├── lib
├── misc
├── pkg
├── robots.txt
├── src
└── test

8 directories, 7 files

➜  go tree -L 1
.
├── bin
├── pkg
└── src

public interface Transportation{ 
    void fly(); 
} 
public class Plane implements Fly{ 
    public void fly() { 
      System.out.println("Plane fly"); 
    } 
}

#include <iostream>
 
using namespace std;
 
// 基类
class Shape 
{
public:
   // 提供接口框架的纯虚函数
   virtual int getArea() = 0;
   void setWidth(int w)
   {
      width = w;
   }
   void setHeight(int h)
   {
      height = h;
   }
protected:
   int width;
   int height;
};
 
// 派生类
class Rectangle: public Shape
{
public:
   int getArea()
   { 
      return (width * height); 
   }
};
class Triangle: public Shape
{
public:
   int getArea()
   { 
      return (width * height)/2; 
   }
};
 
int main(void)
{
   Rectangle Rect;
   Triangle  Tri;
 
   Rect.setWidth(5);
   Rect.setHeight(7);
   // 输出对象的面积
   cout << "Total Rectangle area: " << Rect.getArea() << endl;
 
   Tri.setWidth(5);
   Tri.setHeight(7);
   // 输出对象的面积
   cout << "Total Triangle area: " << Tri.getArea() << endl; 
 
   return 0;
}

➜  src go doc fmt.Fprintf
package fmt // import "fmt"
func Fprintf(w io.Writer, format string, a ...interface{}) (n int, err error)
    Fprintf formats according to a format specifier and writes to w. It returns
    the number of bytes written and any write error encountered.

  1 package main
  2
  3 import (
  4     "fmt"
  5     "os"
  6 )
  7
  8 func main() {
  9     const name, age = "Kim", 22
 10     n, err := fmt.Fprintf(os.Stdout, "%s is %d years old.\n", name, age)
 11
 12     // The n and err return values from Fprintf are
 13     // those returned by the underlying io.Writer.
 14     if err != nil {
 15         fmt.Fprintf(os.Stderr, "Fprintf: %v\n", err)
 16     }
 17     fmt.Printf("%d bytes written.\n", n)
 18
 19 }

➜  src go run /tmp/Fprintf.go

Kim is 22 years old.

21 bytes written.

➜  src go doc io.Writer

package io // import "io"

type Writer interface {

Write(p []byte) (n int, err error)

}

    Writer is the interface that wraps the basic Write method.

    Write writes len(p) bytes from p to the underlying data stream. It returns

    the number of bytes written from p (0 <= n <= len(p)) and any error

    encountered that caused the write to stop early. Write must return a non-nil

    error if it returns n < len(p). Write must not modify the slice data, even

    temporarily.

➜  src go doc os.Stdout

package os // import "os"

var (

Stdin  = NewFile(uintptr(syscall.Stdin), "/dev/stdin")

Stdout = NewFile(uintptr(syscall.Stdout), "/dev/stdout")

Stderr = NewFile(uintptr(syscall.Stderr), "/dev/stderr")

)

    Stdin, Stdout, and Stderr are open Files pointing to the standard input,

    standard output, and standard error file descriptors.

    Note that the Go runtime writes to standard error for panics and crashes;

    closing Stderr may cause those messages to go elsewhere, perhaps to a file

    opened later.

➜  src go doc os.NewFile

package os // import "os"

func NewFile(fd uintptr, name string) *File

    NewFile returns a new File with the given file descriptor and name. The

    returned value will be nil if fd is not a valid file descriptor. On Unix

    systems, if the file descriptor is in non-blocking mode, NewFile will

    attempt to return a pollable File (one for which the SetDeadline methods

    work).

package os // import "os"
type File struct {
// Has unexported fields.
}
    File represents an open file descriptor.
func Create(name string) (*File, error)
func NewFile(fd uintptr, name string) *File
func Open(name string) (*File, error)
func OpenFile(name string, flag int, perm FileMode) (*File, error)
func (f *File) Chdir() error
func (f *File) Chmod(mode FileMode) error
func (f *File) Chown(uid, gid int) error
func (f *File) Close() error
func (f *File) Fd() uintptr
func (f *File) Name() string
func (f *File) Read(b []byte) (n int, err error)
func (f *File) ReadAt(b []byte, off int64) (n int, err error)
func (f *File) Readdir(n int) ([]FileInfo, error)
func (f *File) Readdirnames(n int) (names []string, err error)
func (f *File) Seek(offset int64, whence int) (ret int64, err error)
func (f *File) SetDeadline(t time.Time) error
func (f *File) SetReadDeadline(t time.Time) error
func (f *File) SetWriteDeadline(t time.Time) error
func (f *File) Stat() (FileInfo, error)
func (f *File) Sync() error
func (f *File) SyscallConn() (syscall.RawConn, error)
func (f *File) Truncate(size int64) error
func (f *File) Write(b []byte) (n int, err error)
func (f *File) WriteAt(b []byte, off int64) (n int, err error)
func (f *File) WriteString(s string) (n int, err error)