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6 package doc
7
8 import (
9 "cmd/go/internal/base"
10 "cmd/go/internal/cfg"
11 "context"
12 )
13
14 var CmdDoc = &base.Command{
15 Run: runDoc,
16 UsageLine: "go doc [doc flags] [package|[package.]symbol[.methodOrField]]",
17 CustomFlags: true,
18 Short: "show documentation for package or symbol",
19 Long: `
20 Doc prints the documentation comments associated with the item identified by its
21 arguments (a package, const, func, type, var, method, or struct field)
22 followed by a one-line summary of each of the first-level items "under"
23 that item (package-level declarations for a package, methods for a type,
24 etc.).
25
26 Doc accepts zero, one, or two arguments.
27
28 Given no arguments, that is, when run as
29
30 go doc
31
32 it prints the package documentation for the package in the current directory.
33 If the package is a command (package main), the exported symbols of the package
34 are elided from the presentation unless the -cmd flag is provided.
35
36 When run with one argument, the argument is treated as a Go-syntax-like
37 representation of the item to be documented. What the argument selects depends
38 on what is installed in GOROOT and GOPATH, as well as the form of the argument,
39 which is schematically one of these:
40
41 go doc <pkg>
42 go doc <sym>[.<methodOrField>]
43 go doc [<pkg>.]<sym>[.<methodOrField>]
44 go doc [<pkg>.][<sym>.]<methodOrField>
45
46 The first item in this list matched by the argument is the one whose documentation
47 is printed. (See the examples below.) However, if the argument starts with a capital
48 letter it is assumed to identify a symbol or method in the current directory.
49
50 For packages, the order of scanning is determined lexically in breadth-first order.
51 That is, the package presented is the one that matches the search and is nearest
52 the root and lexically first at its level of the hierarchy. The GOROOT tree is
53 always scanned in its entirety before GOPATH.
54
55 If there is no package specified or matched, the package in the current
56 directory is selected, so "go doc Foo" shows the documentation for symbol Foo in
57 the current package.
58
59 The package path must be either a qualified path or a proper suffix of a
60 path. The go tool's usual package mechanism does not apply: package path
61 elements like . and ... are not implemented by go doc.
62
63 When run with two arguments, the first must be a full package path (not just a
64 suffix), and the second is a symbol, or symbol with method or struct field.
65 This is similar to the syntax accepted by godoc:
66
67 go doc <pkg> <sym>[.<methodOrField>]
68
69 In all forms, when matching symbols, lower-case letters in the argument match
70 either case but upper-case letters match exactly. This means that there may be
71 multiple matches of a lower-case argument in a package if different symbols have
72 different cases. If this occurs, documentation for all matches is printed.
73
74 Examples:
75 go doc
76 Show documentation for current package.
77 go doc Foo
78 Show documentation for Foo in the current package.
79 (Foo starts with a capital letter so it cannot match
80 a package path.)
81 go doc encoding/json
82 Show documentation for the encoding/json package.
83 go doc json
84 Shorthand for encoding/json.
85 go doc json.Number (or go doc json.number)
86 Show documentation and method summary for json.Number.
87 go doc json.Number.Int64 (or go doc json.number.int64)
88 Show documentation for json.Number's Int64 method.
89 go doc cmd/doc
90 Show package docs for the doc command.
91 go doc -cmd cmd/doc
92 Show package docs and exported symbols within the doc command.
93 go doc template.new
94 Show documentation for html/template's New function.
95 (html/template is lexically before text/template)
96 go doc text/template.new # One argument
97 Show documentation for text/template's New function.
98 go doc text/template new # Two arguments
99 Show documentation for text/template's New function.
100
101 At least in the current tree, these invocations all print the
102 documentation for json.Decoder's Decode method:
103
104 go doc json.Decoder.Decode
105 go doc json.decoder.decode
106 go doc json.decode
107 cd go/src/encoding/json; go doc decode
108
109 Flags:
110 -all
111 Show all the documentation for the package.
112 -c
113 Respect case when matching symbols.
114 -cmd
115 Treat a command (package main) like a regular package.
116 Otherwise package main's exported symbols are hidden
117 when showing the package's top-level documentation.
118 -short
119 One-line representation for each symbol.
120 -src
121 Show the full source code for the symbol. This will
122 display the full Go source of its declaration and
123 definition, such as a function definition (including
124 the body), type declaration or enclosing const
125 block. The output may therefore include unexported
126 details.
127 -u
128 Show documentation for unexported as well as exported
129 symbols, methods, and fields.
130 `,
131 }
132
133 func runDoc(ctx context.Context, cmd *base.Command, args []string) {
134 base.Run(cfg.BuildToolexec, base.Tool("doc"), args)
135 }
136
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