go doc 接受零个，一个或两个参数。
go doc <pkg> go doc <sym>[.<methodOrField>] go doc [<pkg>.]<sym>[.<methodOrField>] go doc [<pkg>.][<sym>.]<methodOrField>
go doc <pkg> <sym>[.<methodOrField>]
要获得完整的文档，请运行 go help doc 。
usage: go doc [-u] [-c] [package|[package.]symbol[.method]] Doc prints the documentation comments associated with the item identified by its arguments (a package, const, func, type, var, or method) 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.). Doc accepts zero, one, or two arguments. Given no arguments, that is, when run as go doc it prints the package documentation for the package in the current directory. If the package is a command (package main), the exported symbols of the package are elided from the presentation unless the -cmd flag is provided. When run with one argument, the argument is treated as a Go-syntax-like representation of the item to be documented. What the argument selects depends on what is installed in GOROOT and GOPATH, as well as the form of the argument, which is schematically one of these: go doc
go doc [. ] go doc [ .] [. ] go doc [ .][ .] The first item in this list matched by the argument is the one whose documentation is printed. (See the examples below.) However, if the argument starts with a capital letter it is assumed to identify a symbol or method in the current directory. For packages, the order of scanning is determined lexically in breadth-first order. That is, the package presented is the one that matches the search and is nearest the root and lexically first at its level of the hierarchy. The GOROOT tree is always scanned in its entirety before GOPATH. If there is no package specified or matched, the package in the current directory is selected, so "go doc Foo" shows the documentation for symbol Foo in the current package. The package path must be either a qualified path or a proper suffix of a path. The go tool's usual package mechanism does not apply: package path elements like . and ... are not implemented by go doc. When run with two arguments, the first must be a full package path (not just a suffix), and the second is a symbol or symbol and method; this is similar to the syntax accepted by godoc: go doc [. ] In all forms, when matching symbols, lower-case letters in the argument match either case but upper-case letters match exactly. This means that there may be multiple matches of a lower-case argument in a package if different symbols have different cases. If this occurs, documentation for all matches is printed. Examples: go doc Show documentation for current package. go doc Foo Show documentation for Foo in the current package. (Foo starts with a capital letter so it cannot match a package path.) go doc encoding/json Show documentation for the encoding/json package. go doc json Shorthand for encoding/json. go doc json.Number (or go doc json.number) Show documentation and method summary for json.Number. go doc json.Number.Int64 (or go doc json.number.int64) Show documentation for json.Number's Int64 method. go doc cmd/doc Show package docs for the doc command. go doc -cmd cmd/doc Show package docs and exported symbols within the doc command. go doc template.new Show documentation for html/template's New function. (html/template is lexically before text/template) go doc text/template.new # One argument Show documentation for text/template's New function. go doc text/template new # Two arguments Show documentation for text/template's New function. At least in the current tree, these invocations all print the documentation for json.Decoder's Decode method: go doc json.Decoder.Decode go doc json.decoder.decode go doc json.decode cd go/src/encoding/json; go doc decode Flags: -c Respect case when matching symbols. -cmd Treat a command (package main) like a regular package. Otherwise package main's exported symbols are hidden when showing the package's top-level documentation. -u Show documentation for unexported as well as exported symbols and methods.