goAOP

Wrote by golang, designed for AOP.

What is goAOP?

goAOP is a package for AOP(golang), it designed for use AOP easily.

When goAOP executes, it will scan all source code files. If these files contain valid aop id, then goAOP will try to add pre-defined code in origin files.

What id is a valid AOP id?

A valid AOP id standard is :

1. A word starts with '@'
2. This word can not end with '@'
3. This word is case-sensitive.

So the follow ids are valid:

1. @middleware-a
2. @middleware
3. @MiddleWare-C

also these follow ids are invalid:

1. middleware-a(not starts with '@')
2. @middleware-c@(ends with '@')
3. @(only has a char '@', not has valid word)

Please note that, since AOP id is case-sensitive, so @middleware-a not equals with @Middleware-A.

How is goAOP work?

Let's take a demo code. Suppose we have a code snippet like bellow (fully code references unitTest dir):

package main

// InvokeSecondFunction demo code snippet
// @middleware-b
func InvokeSecondFunction() {}

When goAOP execute, it scans source code first. It will get a ast struct of source code. Second, goAOP try to parser all decls(decls is a slice contains all declare variable), typically, the comment also is a decl. So goAOP will get all comments of InvokeSecondFunction。

Third, goAOP check whether it( comment of InvokeSecondFunction) has valid AOP id. If it finds valid AOP id, then try to match aop params from configure file. We suppose there has params of '@middleware-b' in configure file like bellow:

[[middleware]]
    id="@middleware-b"
    funcStmt=["""func(){
                    log.Println("middleware-b install")
                }()
            """]
    deferStmt=["""defer func(){
                    log.Println("middleware-b install")
                }()
            """]
    [[middleware.package]]
        name = "log"
        path = """ "github.com/sirupsen/logrus" """

Forth, goAOP will add funcStmt , deferStmt in function body by order.

At last, goAOP also will add package in the head of origin file.

So we can get the last code like that:

package main

import log "github.com/sirupsen/logrus"

// InvokeSecondFunction demo code snippet
// @middleware-b
func InvokeSecondFunction() {
	func(){
		log.Println("middleware-b install")
	}()

	defer func(){
		log.Println("middleware-b install")
	}()
}

If you choose replace origin file, goAOP will cover origin file.

How to build goAOP binary?

In this package, there has a sdk package and a main package. If you want to use goAOP directly, then you can build cli dir.

Execute the follow command:

go build -o bin/aop cli/*

You will get an execute file like follow:

Usage of ./bin/aop:
  -config string
    	The runtime config, default is aop.toml (default "aop.toml")
  -debug
    	Enable / Disable debug output
  -dir string
    	The source code file dir path
  -replace
    	Replace source code file or not, default is true (default true)

Then execute ./bin/aop -config example/aop.toml -dir ./unitTests, you will see the effective.

goAOP also supply a configure file , named aop.toml, in example dir.

How to use goAOP sdk?

aops is sdk dir, developer can invoke sdk in there's code. Since hard to understand go parser package, so developer can reference sdk usage from unit test code in aops dir.

Some use cases.

• Use func as a depend condition.