A common pattern I use is:
resource.open()
defer resource.close()
sometimes checking errors in between, which leads to:
err := resource.open()
if err != nil{
//do error stuff and return
}
defer resource.close()
Sometimes I will need multiple open/close resources in a row, leading to a variation of the previous 5 lines to be repeated one after another. This variation may be repeated verbatim several times in my code (where I need all the same resources).
It would be wonderful to wrap all this in a function. However doing so would close the resource as soon as the function call is over. Is there any way around this - either deferring to a "level up" the call stack or some other way?
One way to do this is using an "initializer" function with callback:
func WithResources(f func(Resource1, Resource2)) {
r1:=NewResource1()
defer r1.Close()
r2:=NewResource2()
defer r2.Close()
f(r1,r2)
}
func F() {
WithResources(func(r1 Resource1, r2 Resource2) {
// Use r1, r2
})
}
The signature of the function f depends on your exact use case.
Another way is to use a struct for a resource set:
type Resources struct {
R1 Resource1
R2 Resource2
...
}
func NewResources() *Resources {
r:=&Resources{}
r.R1=NewR1()
r.R2=NewR2()
return r
}
func (r *Resources) Close() {
r.R1.Close()
r.R2.Close()
}
func f() {
r:=NewResources()
defer r.Close()
...
}