[lectures] Add modules lecture.
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Arseny Balobanov
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lectures/05-modules/lectures.slide
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lectures/05-modules/lectures.slide
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Modules
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Лекция 5
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Арсений Балобанов
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* Before modules
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* Before modules
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Install go.
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# export PATH=$PATH:$GOROOT/bin
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# go version
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go version go1.10.8 linux/amd64
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Create workspace.
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mkdir -p go
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export GOPATH=./go
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- *GOROOT* -- where go distribution is installed
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- *GOPATH* -- where all go code is stored
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* Before modules
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# go help
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Go is a tool for managing Go source code.
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Usage:
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go command [arguments]
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The commands are:
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build compile packages and dependencies
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clean remove object files and cached files
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doc show documentation for package or symbol
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env print Go environment information
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bug start a bug report
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fix update packages to use new APIs
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fmt gofmt (reformat) package sources
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generate generate Go files by processing source
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get download and install packages and dependencies
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install compile and install packages and dependencies
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list list packages
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run compile and run Go program
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test test packages
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tool run specified go tool
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version print Go version
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vet report likely mistakes in packages
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...
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* Before modules
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Use *go*help*[command]* for more information about a command.
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# go help env
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usage: go env [-json] [var ...]
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Env prints Go environment information.
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By default env prints information as a shell script
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(on Windows, a batch file). If one or more variable
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names is given as arguments, env prints the value of
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each named variable on its own line.
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The -json flag prints the environment in JSON format
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instead of as a shell script.
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For more about environment variables, see 'go help environment'.
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* Before modules
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# go env
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GOARCH="amd64"
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GOBIN=""
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GOCACHE="/root/.cache/go-build"
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GOEXE=""
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GOHOSTARCH="amd64"
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GOHOSTOS="linux"
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GOOS="linux"
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GOPATH="/go"
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GORACE=""
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GOROOT="/usr/local/go"
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GOTMPDIR=""
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GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
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GCCGO="gccgo"
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CC="gcc"
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CXX="g++"
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CGO_ENABLED="1"
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CGO_CFLAGS="-g -O2"
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CGO_CPPFLAGS=""
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CGO_CXXFLAGS="-g -O2"
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CGO_FFLAGS="-g -O2"
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CGO_LDFLAGS="-g -O2"
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PKG_CONFIG="pkg-config"
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GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -gno-record-gcc-switches"
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* Before modules
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- *GOARCH* -- target compilation architecture, e.g. amd64, arm
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- *GOOS* -- target operating system, e.g. linux, darwin, windows
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* Before modules
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- *go*install* -- compiles and installs the packages named by the import paths.
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.link https://github.com/golang/vgo https://github.com/golang/vgo
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# go install golang.org/x/vgo
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can't load package: package golang.org/x/vgo: cannot find package "golang.org/x/vgo" in any of:
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/usr/local/go/src/golang.org/x/vgo (from $GOROOT)
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/go/src/golang.org/x/vgo (from $GOPATH)
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* Before modules
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- *go*get* -- downloads the packages named by the import paths, along with their dependencies.
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It then installs the named packages like *go*install*.
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# go get golang.org/x/vgo
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# tree -L 4 $GOPATH
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/go
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|-- bin
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| `-- vgo
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`-- src
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`-- golang.org
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`-- x
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|-- text
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`-- vgo
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- *golang.org/x* -- namespace
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- *text*, *vgo* -- projects
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* Before modules
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- *$GOPATH/bin* -- executable files
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- *$GOPATH/src* -- source files e.g. .go
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* Before modules
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# mkdir -p src/github.com/verytable/hello
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# cat src/github.com/verytable/hello/main.go
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package main
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func main() {
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fmt.Println("Hello, World!")
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}
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- *go*run* compiles and runs the main package comprising the named Go source files.
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# go run src/github.com/verytable/hello/main.go
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# command-line-arguments
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src/github.com/verytable/hello/main.go:4:2: undefined: fmt
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* Before modules
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Install goimports
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# go get golang.org/x/tools/cmd/goimports
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# tree -L 2 $GOPATH
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/go
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|-- bin
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| |-- goimports
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| `-- vgo
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`-- src
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|-- github.com
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`-- golang.org
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# export PATH=$GOPATH/bin:$PATH
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* Before modules
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Fix imports and format file.
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# goimports -w src/github.com/verytable/hello/main.go
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# cat src/github.com/verytable/hello/main.go
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package main
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import "fmt"
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func main() {
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fmt.Println("Hello, World!")
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}
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Compile and run.
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# go run src/github.com/verytable/hello/main.go
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Hello, World!
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* Before modules
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- *gofmt* -- gofmt formats Go programs
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- *go*fmt* -- runs the command 'gofmt -l -w'
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- *goimports* -- updates Go import lines, adding missing ones and removing unreferenced ones; also formats your code
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* Before modules
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# go build github.com/verytable/hello
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# ./hello
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Hello, World!
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- *go*build* -- compiles the packages named by the import paths along with their dependencies, but it does not install the results.
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* Before modules
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# go install github.com/verytable/hello
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# tree -L 2 $GOPATH
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/go
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|-- bin
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| |-- goimports
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| |-- hello
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| `-- vgo
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|-- hello
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`-- src
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|-- github.com
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`-- golang.org
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Run installed binary.
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# $GOPATH/bin/hello
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Hello, World!
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- *go*install* -- compiles and installs the packages named by the import paths.
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* Before modules
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# mkdir -p src/github.com/verytable/string
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# cat src/github.com/verytable/string/string.go
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package string
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func Reverse(s string) string {
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b := []byte(s)
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for i := 0; i < len(b)/2; i++ {
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j := len(b) - i - 1
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b[i], b[j] = b[j], b[i]
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}
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return string(b)
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}
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Compile.
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# go build github.com/verytable/string
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# echo $?
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0
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* Before modules
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Install package
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# go install github.com/verytable/string
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# tree -L 2 $GOPATH
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/go
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|-- bin
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| |-- goimports
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| |-- hello
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| `-- vgo
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|-- pkg
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| `-- linux_amd64
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`-- src
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|-- github.com
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`-- golang.org
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- *$GOPATH/pkg* -- compiled libraries e.g. .a
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* Before modules
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# tree -L 4 $GOPATH/pkg
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/go/pkg
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`-- linux_amd64
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`-- github.com
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`-- verytable
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`-- string.a
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- *linux_amd64* -- ${GOOS}_${GOARCH}
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* Before modules
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Let's use string package.
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# cat src/github.com/verytable/hello/main.go
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package main
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import (
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"fmt"
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"github.com/verytable/string"
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)
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func main() {
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fmt.Println(string.Reverse("Hello, World!"))
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}
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Install and run.
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# go install github.com/verytable/hello
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# hello
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!dlroW ,olleH
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* Before modules
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Add dependency.
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# cat src/github.com/verytable/hello/main.go
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package main
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import (
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"fmt"
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"github.com/verytable/string"
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"rsc.io/sampler"
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)
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func main() {
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fmt.Println(string.Reverse("Hello, World!"))
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fmt.Println(sampler.Glass())
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}
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Compile and run.
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# go run src/github.com/verytable/hello/main.go
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src/github.com/verytable/hello/main.go:7:2: cannot find package "rsc.io/sampler" in any of:
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/usr/local/go/src/rsc.io/sampler (from $GOROOT)
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/go/src/rsc.io/sampler (from $GOPATH)
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* Before modules
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Download dependencies.
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# go get -v github.com/verytable/hello
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Fetching https://rsc.io/sampler?go-get=1
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Parsing meta tags from https://rsc.io/sampler?go-get=1 (status code 200)
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get "rsc.io/sampler": found meta tag get.metaImport{Prefix:"rsc.io/sampler", VCS:"git", RepoRoot:"https://github.com/rsc/sampler"} at https://rsc.io/sampler?go-get=1
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rsc.io/sampler (download)
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Compile and run.
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# go run src/github.com/verytable/hello/main.go
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!dlroW ,olleH
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I can eat glass and it doesn't hurt me.
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* Before modules
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- *go*list* -- lists the packages named by the import paths, one per line.
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List packages.
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# go list github.com/verytable/hello
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github.com/verytable/hello
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List package files.
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# go list -f {{.GoFiles}} github.com/verytable/hello
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[main.go]
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List package imports.
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# go list -f {{.Imports}} github.com/verytable/hello
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[fmt github.com/verytable/string rsc.io/sampler]
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Run 'go help list' to see all format options.
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* Before modules
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- A workspace ($GOPATH) contains many version control repositories (managed by Git, for example).
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- Each repository contains one or more packages.
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- Each package consists of one or more Go source files in a single directory.
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- The path to a package's directory determines its import path.
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* Modules
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* Modules
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# go mod init github.com/verytable/hello
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go: creating new go.mod: module github.com/verytable/hello
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# cat go.mod
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module github.com/verytable/hello
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go 1.16
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- *package* -- collection of source files in the same directory that are compiled together
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- *module* -- collection of related Go packages that are released together
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- github.com/verytable/hello -- *module*path*, the import path prefix for all packages within the module
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* Modules
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- *import*path* -- string used to import a package
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For example, the module `github.com/google/go-cmp` contains a package in the directory `cmp/`.
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That package's import path is `github.com/google/go-cmp/cmp`.
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* Modules
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# cat hello.go
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package main
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import "fmt"
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func main() {
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fmt.Println("Hello, world!")
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}
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Install binary.
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# go env -w GOBIN=/tmp/bin
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# go install .
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# /tmp/bin/hello
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Hello, world!
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# go env -u GOBIN
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* Modules
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# git init
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Initialized empty Git repository in /tmp/hello/.git/
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# git add hello.go go.mod
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# git commit -m "initial commit"
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[master (root-commit) f22a6c1] initial commit
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2 files changed, 10 insertions(+)
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create mode 100644 go.mod
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create mode 100644 hello.go
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* Modules
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# mkdir -p morestrings
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# cat morestrings/reverse.go
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package morestrings
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func ReverseRunes(s string) string {
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r := []rune(s)
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for i, j := 0, len(r)-1; i < len(r)/2; i, j = i+1, j-1 {
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r[i], r[j] = r[j], r[i]
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}
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return string(r)
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}
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# go build ./morestrings
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* Modules
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Check build.
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# go build ./morestrings
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- *GOCACHE* -- 'go build' internal cache location.
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go command caches build outputs for reuse in future builds. Run 'go help cache' for more info.
|
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* Modules
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Use subpackage.
|
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|
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# cat hello.go
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package main
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import (
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"fmt"
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"github.com/verytable/hello/morestrings"
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)
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func main() {
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fmt.Println(morestrings.ReverseRunes("!oG ,olleH"))
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}
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# go install github.com/verytable/hello
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# hello
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Hello, Go!
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* Modules
|
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Add external dependency.
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|
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# cat hello.go
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package main
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import (
|
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"fmt"
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"github.com/google/go-cmp/cmp"
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"github.com/verytable/hello/morestrings"
|
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)
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func main() {
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fmt.Println(morestrings.ReverseRunes("!oG ,olleH"))
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fmt.Println(cmp.Diff("Hello World", "Hello Go"))
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}
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* Modules
|
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|
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# go mod tidy
|
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go: finding module for package github.com/google/go-cmp/cmp
|
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go: downloading github.com/google/go-cmp v0.5.5
|
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go: found github.com/google/go-cmp/cmp in github.com/google/go-cmp v0.5.5
|
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# go install
|
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# hello
|
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Hello, Go!
|
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string(
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- "Hello World",
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+ "Hello Go",
|
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)
|
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|
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Requirements are stored in go.mod.
|
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|
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# cat go.mod
|
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module github.com/verytable/hello
|
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|
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go 1.16
|
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|
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require github.com/google/go-cmp v0.5.5
|
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|
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* Modules
|
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|
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- *go*mod*tidy* makes sure go.mod matches the source code in the module
|
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|
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Run 'go mod help tidy' for details.
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|
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* Modules
|
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|
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Modules are downloaded to *$GOPATH/pkg/mod*.
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|
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# tree -L 2 $GOPATH/pkg/mod/github.com/google
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...
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├── go-cmp@v0.4.0
|
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│ ├── cmp
|
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│ ├── CONTRIBUTING.md
|
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│ ├── go.mod
|
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│ ├── go.sum
|
||||
│ ├── LICENSE
|
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│ └── README.md
|
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├── go-cmp@v0.5.5
|
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│ ├── cmp
|
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│ ├── CONTRIBUTING.md
|
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│ ├── go.mod
|
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│ ├── go.sum
|
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│ ├── LICENSE
|
||||
│ └── README.md
|
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...
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|
||||
* Modules
|
||||
|
||||
- *go*clean* -- removes object files from package source directories
|
||||
|
||||
Run 'go clean -modcache' to remove all downloaded modules.
|
||||
|
||||
* Modules
|
||||
|
||||
# go list -m -f {{.Path}}{{.Version}} all
|
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github.com/verytable/hello
|
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github.com/google/go-cmpv0.5.5
|
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golang.org/x/xerrorsv0.0.0-20191204190536-9bdfabe68543
|
||||
|
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Format options.
|
||||
|
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type Module struct {
|
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Path string // module path
|
||||
Version string // module version
|
||||
Versions []string // available module versions (with -versions)
|
||||
Replace *Module // replaced by this module
|
||||
Time *time.Time // time version was created
|
||||
Update *Module // available update, if any (with -u)
|
||||
Main bool // is this the main module?
|
||||
Indirect bool // is this module only an indirect dependency of main module?
|
||||
Dir string // directory holding files for this module, if any
|
||||
GoMod string // path to go.mod file used when loading this module, if any
|
||||
GoVersion string // go version used in module
|
||||
Retracted string // retraction information, if any (with -retracted or -u)
|
||||
Error *ModuleError // error loading module
|
||||
}
|
||||
|
||||
|
||||
|
||||
* Modules
|
||||
|
||||
- *go.sum* -- stores the expected cryptographic hashes of the content of specific module versions
|
||||
|
||||
# cat go.sum
|
||||
github.com/google/go-cmp v0.5.5 h1:Khx7svrCpmxxtHBq5j2mp/xVjsi8hQMfNLvJFAlrGgU=
|
||||
github.com/google/go-cmp v0.5.5/go.mod h1:v8dTdLbMG2kIc/vJvl+f65V22dbkXbowE6jgT/gNBxE=
|
||||
golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
|
||||
golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
|
||||
|
||||
* Modules
|
||||
|
||||
- *go*mod*graph* prints the module requirement graph
|
||||
|
||||
# go mod graph
|
||||
github.com/verytable/hello github.com/google/go-cmp@v0.5.5
|
||||
github.com/google/go-cmp@v0.5.5 golang.org/x/xerrors@v0.0.0-20191204190536-9bdfabe68543
|
||||
|
||||
* Modules
|
||||
|
||||
- *go*mod*why* shows a shortest path in the import graph from the main module to the package
|
||||
|
||||
# go mod why golang.org/x/xerrors
|
||||
# golang.org/x/xerrors
|
||||
github.com/verytable/hello
|
||||
github.com/google/go-cmp/cmp
|
||||
github.com/google/go-cmp/cmp.test
|
||||
github.com/google/go-cmp/cmp/cmpopts
|
||||
golang.org/x/xerrors
|
||||
|
||||
* Modules
|
||||
|
||||
- *go*mod*vendor* -- copies module requirements to ./vendor directory
|
||||
|
||||
Vendor dependencies.
|
||||
|
||||
# go mod vendor
|
||||
# tree -L 3 ./vendor
|
||||
./vendor
|
||||
├── github.com
|
||||
│ └── google
|
||||
│ └── go-cmp
|
||||
└── modules.txt
|
||||
|
||||
* Modules
|
||||
|
||||
# cat vendor/modules.txt
|
||||
# github.com/google/go-cmp v0.5.5
|
||||
## explicit
|
||||
github.com/google/go-cmp/cmp
|
||||
github.com/google/go-cmp/cmp/internal/diff
|
||||
github.com/google/go-cmp/cmp/internal/flags
|
||||
github.com/google/go-cmp/cmp/internal/function
|
||||
github.com/google/go-cmp/cmp/internal/value
|
||||
|
||||
|
||||
* Modules
|
||||
|
||||
- *GO111MODULE* controls how Go imports packages. on, off or auto.
|
||||
|
||||
*Go*1.11*
|
||||
|
||||
- *on* will force using Go modules even if the project is in your GOPATH. Requires go.mod to work.
|
||||
- *off* forces Go to behave the GOPATH way, even outside of GOPATH.
|
||||
- *auto* (default). In this mode, Go will behave
|
||||
similarly to *on* when you are outside of GOPATH,
|
||||
similarly to *off* when you are inside the GOPATH even if a go.mod is present.
|
||||
|
||||
|
||||
* Modules
|
||||
|
||||
*Go*1.13*
|
||||
|
||||
*GO111MODULE=auto*
|
||||
|
||||
- *on* anywhere there is a go.mod OR anywhere outside the GOPATH even if there is no go.mod.
|
||||
- *off* in the GOPATH with no go.mod.
|
||||
|
||||
* Modules
|
||||
|
||||
*Go*1.16*
|
||||
|
||||
*on* is a default.
|
||||
|
||||
- *auto* could be used for previous previous behaviour
|
||||
|
||||
*Go*1.17*
|
||||
|
||||
*GO111MODULE* is will be ignored.
|
||||
|
||||
* Ссылки:
|
||||
|
||||
.link https://golang.org/cmd/go/ - go cmd
|
||||
.link https://play-with-go.dev/ - play-with-go
|
||||
Loading…
Reference in a new issue