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Compile Time Code Weaving with Go
https://github.com/deferpanic/goweave
I like your software but…
What sucks about Go?
Do you know about AspectJ?
Really?
I’m not a code purist
“Which is our full time job. Write a program to write
a program”- rob pike / gopherfest 2015
Go is Actually a Decent Fit
Prior Artgo fmtgo fix
go generate
go fix
No WrappingNo code residue
Non-trivial amount of work
Regex/Sed Doesn’t Work
scopemany
packagesmany refs
Aspect Oriented Programming
Cross-Cutting Concern
Contains behavior that is prominent in many places but don’t really have anything to do with your business logic.
Logging is a canonical example
logging.Error.Println(“got here”)
logging.Error.Println(“got here”)
logging.Error.Println(“got here”)
Pointcut
an expression that details where to apply your behavior
like a regex but on the ast
Advice
fmt.Println("Hello, 世界 ")
Aspect
the combination of a pointcut and advice
Sample PointCuts
Call
Before, after or wrap around calling a function.
func blah() { some.stuff()}
func blah() { fmt.Println(“before”) some.stuff()}
before
after
Execute
Before or after inside executing a method.
func blah() { stuff()}
func stuff() {}
before
afterfunc blah() { stuff()}
func stuff() { fmt.Println(“stuff”)}
Within
Every single call within a method.
func blah() { beforeEach() slowCall() beforeEach() fastcall() }
before
after
func blah() { slowCall() fastcall() }
get
Before or After Every Get to a Variable
before
after
func blah() { x := “stuff” fmt.Println(x)}
func blah() { x := “stuff” fmt.Println(“before getting x”) fmt.Println(x)}
set
Before or After Every Set to a Variable
before
after
func blah() { x := “stuff” fmt.Println(x)}
func blah() { fmt.Println(“before setting x”) x := “stuff” fmt.Println(x)}
declaration
Before or After Every Variable Declaration
before
after
func blah() { ch := make(chan int, 2) ch <- 1}
func blah() { fmt.Println(“before make”) ch := make(chan int, 2) ch <- 1}
Logging
Monitoring
Performance Analysis
Debugging & Tracing
Undo Functionality
Behavior Mutation
Security
Transactions
Log every call to Itoa
Validation
Time Database Query Latencies
Ensure we log every panic in a goroutine
the loom
central repository for storing .weave files
https://github.com/deferpanic/goweave
https://github.com/deferpanic/loom
