golang 2

Practicing golang

golang Hello

Everything in go is a package
I use docker to practice go

package main

import "fmt"

We import the fmt package

go get  github.com/golang/example/hello         -- > this command will go and get the hello program on github


go get github.com/golang/example/hello/...   - > this will get the program and builds all the code under the directory

for gover in 1.2 1.3 1.4; do docker run -v $GOPATH:/go golang:$gover sh -c "go get github.com/golang/example/hello/... && hello "; done

docker run -it  -v $GOPATH:/go  golang:1.2

docker run -it golang:1.2   sh -c "go get github.com/golang/example/hello/... && hello "

for i in 1.2 1.3 1.5 1.4 1.6 ; do docker run -v $GOPATH/src:/go/src golang:$i  sh -c "go get github.com/golang/example/hello/... && hello && echo $i"; done

Hello, Go examples!

1.2

Hello, Go examples!

1.3

Hello, Go examples!

1.5

Hello, Go examples!

1.4

Hello, Go examples!

1.6

So , this is the way to run the code in multiple versions of Go

If we mount just the $GOPATH  instead of   $GOPATH/src , then  we run into following error

# github.com/golang/example/hello

src/github.com/golang/example/hello/hello.go:22: import /go/pkg/linux_amd64/github.com/golang/example/stringutil.a: object is [linux amd64 go1.2.2 X:none] expected [linux amd64 go1.5.4 X:none]

# github.com/golang/example/hello

src/github.com/golang/example/hello/hello.go:22: import /go/pkg/linux_amd64/github.com/golang/example/stringutil.a: object is [linux amd64 go1.2.2 X:none] expected 

This is because ,  the code is first compiled in 1.2  and for later versions of go , there is a link , that is created between the compiled version of go and the rest of the versions

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Minimizing the size of the docker images

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