Preface

First , Quote seven cattle cloud storage team in 《Go Language programming 》 Point of view （ The first 7 Chapter , The first 9 section ）：

For now , Distribute in binary Go Bag is not very realistic . because Go The language has very strict compatibility control , Any different version number will result in the failure to link packages . therefore , If you use Go Language developed a library , Then the most appropriate way to distribute the library is to package the source code package directly and distribute it , Compiled by the user .

however , The author thinks Go Language compilation and C The language is the same , With compilation 、 Link phase . therefore , It is necessary to understand 、 Study Go Dynamic library and static library of language , It also helps distribute packages later .

Example project

A standard Golang The project includes 3 A catalog

• bin Put the executable
• pkg Put the static library
• src Put the source code

[[email protected] goprj]$ ls
bin  pkg  src
[[email protected] goprj]$ tree
.
├── bin
├── pkg
│   ├── gccgo_linux_amd64
│   └── linux_amd64
└── src
    ├── calc
    │   ├── fibonacci
    │   │   ├── fibonacci.go
    │   │   └── fibonacci_test.go
    │   └── calc.go
    └── simplemath
        ├── add.go
        └── sqrt.go

6 directories, 5 files
[[email protected] goprj]$

pkg

Wait, I use google Of gc Tool chain , Also used gnu Of gccgo Tool chain , therefore pkg There are two folders below

• gccgo_linux_amd64 discharge gccgo Generated static library
• linux_amd64 discharge gc Generated static library

src

The code has 2 Packages and 1 Executable files

• calc The main program
• calc/fibonacci Provide Fibonacci number correlation function
• simplemath Provide basic mathematical operations

src/calc/calc.go

package main

import "fmt"
import "calc/fibonacci"

func main() {
    
    var res int64
    var err error

    res, err = fibonacci.Fibonacci(30)
    if err != nil {
    
            panic(err.Error())
    } else {
    
            fmt.Println("Result:", res)
    }

    res, err = fibonacci.Fibonacci_r(30)
    if err != nil {
    
            panic(err.Error())
    } else {
    
            fmt.Println("Result:", res)
    }
}

src/calc/calc/fibonacci/fibonacci.go

package fibonacci

import "simplemath"
import "errors"

func Fibonacci(n int64) (int64, error) {
    
    if n < 1 {
    
        err := errors.New("Should be greater than 0!")
        return 0, err
    } else if n > 92 {
    
        err := errors.New("Should be less than 93!")
        return 0, err
    }

    var res int64 = 0
    var tmp int64 = 1
    var idx int64 = 0

    for ; idx < n; idx++ {
    
        res = simplemath.Add(res, tmp)
        res, tmp = tmp, res
    }

    return res, nil
}

func Fibonacci_r(n int64) (int64, error) {
    
    if n < 1 {
    
        err := errors.New("Should be greater than 0!")
        return 0, err
    } else if n < 3 {
    
        return 1, nil
    } else if n > 92 {
    
        err := errors.New("Should be less than 93!")
        return 0, err
    }

    lhs, _ := Fibonacci_r(n - 1)
    rhs, _ := Fibonacci_r(n - 2)
    ret := simplemath.Add(lhs, rhs)
    return ret, nil
}

src/simplemath/add.go

package simplemath

func Add(a int, b int) int {
    
    return a + b
}

src/simplemath/sqrt.go

package simplemath

import "math"

func Sqrt(i int) int {
    
    v := math.Sqrt(float64(i))
    return int(v)
}

One button compilation

First , Add the project path to the environment variable .
then , use go install Command one click compilation

• gc go install ./...
• gccgo go install -compiler gccgo ./...

gc Compiling static libraries

1. use go tool compile Compile binary files
2. use go tool pack Package as a static library

matters needing attention ：

• The same package should be compiled into the same .o file
• gc The naming rule of static libraries is gopackage.a
• You need to use this static library in the future -I and -L Parameters

[[email protected] goprj]$ go tool compile -o simplemath.o src/simplemath/add.go src/simplemath/sqrt.go
[[email protected] goprj]$ go tool pack c pkg/linux_amd64/simplemath.a simplemath.o
[[email protected] goprj]$
[[email protected] goprj]$ go tool compile -o fibonacci.o -I pkg/linux_amd64 src/calc/fibonacci/fibonacci.go
[[email protected] goprj]$ go tool pack c pkg/linux_amd64/calc/fibonacci.a fibonacci.o
[[email protected] goprj]$ 
[[email protected] goprj]$ go tool compile -o calc.o -I pkg/linux_amd64 src/calc/calc.go
[[email protected] goprj]$ go tool link -o bin/calc -L pkg/linux_amd64 calc.o
[[email protected] goprj]$ 

gccgo Compiling static libraries

1. use gccgo Compile binary files
2. use ar Package as a static library
   matters needing attention ：

• The same package should be compiled into the same .o file
• gccgo The naming rule of static libraries is libgopackage.a

[[email protected] goprj]$ gccgo -c -o simplemath.o src/simplemath/add.go src/simplemath/sqrt.go
[[email protected] goprj]$ ar rv pkg/gccgo_linux_amd64/libsimplemath.a simplemath.o
ar: creating pkg/gccgo_linux_amd64/libsimplemath.a
a - simplemath.o
[[email protected] goprj]$ 
[[email protected] goprj]$ gccgo -c -o fibonacci.o -I pkg/gccgo_linux_amd64 src/calc/fibonacci/fibonacci.go
[[email protected] goprj]$ ar rv pkg/gccgo_linux_amd64/calc/libfibonacci.a fibonacci.o
ar: creating pkg/gccgo_linux_amd64/calc/libfibonacci.a
a - fibonacci.o
[[email protected] goprj]$ 
[[email protected] goprj]$ gccgo -c -o calc.o -I pkg/gccgo_linux_amd64 src/calc/calc.go
[[email protected] goprj]$ gccgo -o bin/calc \
>                        -L pkg/gccgo_linux_amd64 \
>                        -L pkg/gccgo_linux_amd64/calc \
>                        calc.o \
>                        -lfibonacci -lsimplemath
[[email protected] goprj]$ 

gccgo Compile dynamic library

gcc Have rich compilation experience , Compilation is also provided go Tools for dynamic libraries .
The easiest way is to use -shared Compilation options

[[email protected] goprj]$ gccgo -shared -fPIC \
>                        -o pkg/gccgo_linux_amd64/libsimplemath.so \
>                        src/simplemath/add.go \
>                        src/simplemath/sqrt.go
[[email protected] goprj]$ gccgo -shared -fPIC \
>                        -o pkg/gccgo_linux_amd64/calc/libfibonacci.so \
>                        -I pkg/gccgo_linux_amd64 \
>                        src/calc/fibonacci/fibonacci.go
[[email protected] goprj]$ 

summary

in general ,go tool Very convenient , Manual compilation is more flexible .