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Anonymous Structs in Go
An anonymous struct is just like a normal struct, but it is defined without a name and therefore cannot be referenced elsewhere in the code.
To create an anonymous struct, just instantiate the instance immediately using a second pair of brackets after declaring the type:
myCar := struct {
Make string
Model string
} {
Make: "tesla",
Model: "model 3"
}
You can even nest anonymous structs as fields within other structs:
type car struct {
Make string
Model string
Height int
Width int
// Wheel is a field containing an anonymous struct
Wheel struct {
Radius int
Material string
}
}
When should you use an anonymous struct?
In general, prefer named structs. Named structs make it easier to read and understand your code, and they have the nice side-effect of being reusable. I sometimes use anonymous structs when I know I won't ever need to use a struct again. For example, sometimes I'll use one to create the shape of some JSON data in HTTP handlers.
If a struct is only meant to be used once, then it makes sense to declare it in such a way that developers down the road won’t be tempted to accidentally use it again.
You can read more about anonymous structs here if you're curious.