Type assertion is not required in the given example (from array of structs to interface), But you need to assert if array of one interface is type casted to array of another interface. I started this thread to know whether this pattern requires a language level change to avoid unwanted array copy and code duplication for similar pattern of code. I agree that there are many ways in Golang to make this code run but shouldn't the language provide an extension to already available syntax to address this in simple and elegant way?
On Thursday, 19 April 2018 21:36:38 UTC+5:30, Jake Montgomery wrote: > > Yes, to use the functions above you will need to copy the slices of > landSpaceto slices of the respective interface types. But I you do not > need to do any type assertions. Like this: > > https://play.golang.org/p/eFTUqpImyPc > package main > > import ( > "fmt" > ) > > type landSpace struct{} > > func (*landSpace) Foo() { > fmt.Println("Foo") > } > > func (*landSpace) Bar() { > fmt.Println("Bar") > } > > type Shape interface { > Foo() > } > > type Property interface { > Bar() > } > > var a []*landSpace > > func processShapes(shapes []Shape) { > for _, s := range shapes { > s.Foo() > } > } > > func evaluateProperties(properties []Property) { > for _, p := range properties { > p.Bar() > } > } > > func main() { > a = append(a, &landSpace{}, &landSpace{}) > > var shapes []Shape > for _, l := range a { > shapes = append(shapes, l) > } > processShapes(shapes) > > var properties []Property > for _, l := range a { > properties = append(properties, l) > } > evaluateProperties(properties) > fmt.Println("Hello, playground") > } > > Is this what you meant? I see how something like shapes = a.([]Shape) would > be convenient to avoid having to do an explicit conversion. Hoever, until > Go has some form of generics, it seems unlikely. Keep in mind that a Shape > and *landSpace are two different types, with different in memory > representations. So to avoid major language changes, the type assertion > would have to create a new slice anyway. > > > On Thursday, April 19, 2018 at 12:59:12 AM UTC-4, Sakthi Natesan wrote: >> >> Usescases that I came across doesn't involve []interface{}. >> >> My usecases will be similar to this sample code >> <https://play.golang.org/p/LezKzpiMndl> >> >> type landSpace struct { >> //consider that landSpace implements all functions from both Shape and >> property interfaces >> ... >> } >> type Shape interface { >> ... >> } >> >> >> type property interface { >> >> ... >> } >> >> >> var a []*landSpace >> >> func processShapes(shapes []Shape) { >> //.... >> } >> >> func evaluateProperties(properties []Property) { >> //.... >> } >> >> >> >> If I want to pass the variable 'a' to both the functions, then I have to >> write two functions to clone and typeAssert to respective interfaces. >> >> >> On Wednesday, 18 April 2018 19:53:33 UTC+5:30, Jan Mercl wrote: >>> >>> On Wed, Apr 18, 2018 at 4:13 PM <nsak...@gmail.com> wrote: >>> >>> When possible, avoid using '[]interface{}' and use just 'interface{}' >>> instead: https://play.golang.org/p/oPtPoGChkMZ. >>> >>> >>> -- >>> >>> -j >>> >> -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
