I think it would be problematic, as the callee signature is limited - func()
error - and with lack of method overloading you will need a lot of WithXXXX
methods…
> On Sep 12, 2018, at 6:58 AM, Mirko Friedenhagen <mfriedenha...@gmx.de> wrote:
>
> Hello,
>
> in Python I may define context managers which do stuff before and after an
> action has taken place.
>
> E.g.:
>
> ```
> class MyContext(object):
> def __enter__(self):
> print("Entering context")
> def __exit__(self, extype_unused, value_unused, traceback_unused):
> print("Exiting context")
>
> if __name__ == "__main__":
> with MyContext():
> print("Inside the context")
> ```
>
> will print:
> Entering context
> Inside the context
> Exiting context
>
> A Golang equivalent I came up with is something like (see
> https://play.golang.org/p/epBGtwZWuln as well)
>
> ```
> package main
>
> import "log"
>
> type Context interface {
> __entry__()
> __exit__()
> }
>
> func WithContext(context Context, f func() error) error {
> context.__entry__()
> defer context.__exit__()
> return f()
> }
>
> type MyContext struct {
> message string
> }
>
> func (context *MyContext) __entry__() {
> log.Print("Entering ", context.message)
> }
>
> func (context *MyContext) __exit__() {
> log.Print("Exiting ", context.message)
> }
>
> func main() {
> var a string
> WithContext(&MyContext{"Hallo"}, func() error {
> log.Print("Inside context")
> a = "Var from context"
> return nil
> })
> log.Print(a)
> }
> ```
>
> Is this idiomatic or are there better ways to implement stuff like this?
>
> Regards
> Mirko
>
>
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