Questions tagged [go-interface]
104 questions
1
vote
1 answer
pointer receiver vs value receiver
Situation:
I've learned about pointer receivers and value receivers. From what I understand: if you want to modify the object itself, you need to use a pointer receiver. I was reading more about interfaces in the go documentation and found this…
phouse512
- 650
- 4
- 15
- 27
1
vote
1 answer
Unmarshaling a JSON integer to an empty interface results in wrong type assertion
I have this code. I expect the interface to be type asserted to int. However, the type of the interface is float64 instead. Can anyone explain why this is happening? And what are the best ways to circumvent it.
package main
import (
"fmt"
…
Keeto
- 4,074
- 9
- 35
- 58
1
vote
1 answer
Is it possible to pass interface obj to interface{} type?
I'm new to golang and I want to implement an overloaded method something similar to C++ overloading, and my code looks something like this:
type someStruct struct {
val int
some string
}
type object interface {
toByte()
}
//…
Ronin Goda
- 234
- 5
- 13
1
vote
1 answer
Is it possible to store a Go type
I've got a handful of interfaces, and n number of structs that arbitrarily implement these interfaces. I'd like to keep an array of types and be able to run a loop over them to see which ones are implemented. Is it possible to store a type like…
estobbart
- 1,137
- 12
- 28
1
vote
1 answer
Create a struct from a byte array
I use the json.Marshal interface to accept a map[string]interface{} and convert it to a []byte (is this a byte array?)
data, _ := json.Marshal(value)
log.Printf("%s\n", data)
I get this output
{"email_address":"joe@me.com","street_address":"123…
7hacker
- 1,928
- 3
- 19
- 32
1
vote
1 answer
Go obtain pointer to struct from interface?
Given an interface, how do I obtain a pointer to the underlying value?
My naive attempt was to use a type assertion like this:
var mytypeptr *MyType = myinterface.(*MyType)
But I get:
interface conversion: MyInterface is MyType, not *MyType
ealfonso
- 6,622
- 5
- 39
- 67
0
votes
0 answers
Appending to slice in map which is type of map[any]any
I want to append to slice in map which is defined as map[any]any
I am having type conversion issues and don't know how to treat result[index][ABSPath] as slice so I can append data to it
Here is the example code:
package main
import (
"fmt"
…
John Doe
- 17
- 1
0
votes
0 answers
Calling functions with unknown number of arguments
I have the following struct:
// fninfo holds a function and its arity.
type fninfo struct {
arity int // number of arguments that fn takes
fn any // fn must take string arguments and return one string
}
and a map of it:
var fnmap =…
ban_javascript
- 339
- 1
- 4
- 16
0
votes
0 answers
Go - Pass callback function to child (imported) package
I have a go program, MyPackage, and a logging package within this, MyPackage/logs. We have a function func Cleanup(params CleanupParams) written in MyPackage that we want to use as a callback in case of any panic within our log function implemented…
MattyAB
- 365
- 2
- 9
- 19
0
votes
1 answer
golang interface and why output is "bad error"?
I try to define "Error" method to type "T", but why value changed??
type T int
func (t T) Error() string {
return "bad error"
}
func main() {
var v interface{} = T(5)
fmt.Println(v) //output: bad error, not 5
}
How to explain this…
linfun486
- 11
- 4
0
votes
1 answer
Why does Go allow a struct to implement an unexported interface present in a different package?
I wrote a sample code to understand how the unexported interface works. In the below example, I have declared the unexported repoInterface in the service package.
TestRepo struct in the repo package implements the unexported repoInterface without…
syedalisait
- 45
- 7
0
votes
2 answers
Go interfaces: is not net.Conn a io.ReadWriteCloser?
I have a question about the uses of interfaces in go. I am still learning the language, so please forgive me if it is a stupid question.
I am playing with a little application that accept and handle TCP connections. Because I want to test the…
Francesco
- 11
- 2
0
votes
1 answer
using maps with any value type as function parameter?
I am trying to create a function which takes in a map as a parameter, where the map uses string keys but the values can be ANY type.
How do I make this work in go? I tried using map[string]interface{} as the parameter type to the function but that…
Atif Ali
- 2,186
- 2
- 12
- 23
0
votes
1 answer
Sharing method implementations between different structs
Say we have 2 structs sharing a property with the same name and purpose, but of different size:
type (
L16 struct {
Length uint16
}
L32 struct {
Length uint32
}
)
The goal is to make those structs have a GetLength…
Greendrake
- 3,657
- 2
- 18
- 24
0
votes
1 answer
Go interfaces and Rust traits, and porting a function from Go to Rust
I have this piece of go code -
type Server struct {
enforcerMap map[int]*casbin.Enforcer
adapterMap map[int]persist.Adapter
}
func NewServer() *Server {
s := Server{}
s.enforcerMap = map[int]*casbin.Enforcer{}
s.adapterMap =…
eth_sign
- 63
- 7