Reflect Type comparison
I want to ensure that the type of map keys is string. Key() method returns Type and I'm not sure what is the right way to check if it's string. The only thing came to my mind is:
if v.Type().Key() == reflect.TypeOf("")
fmt.Print("It is string")
Is it the right way?
go reflection asked Nov 12 at 11:32
Russiancold
691315
add a comment |
I want to ensure that the type of map keys is string. Key() method returns Type and I'm not sure what is the right way to check if it's string. The only thing came to my mind is:
if v.Type().Key() == reflect.TypeOf("")
fmt.Print("It is string")
Is it the right way?
go reflection asked Nov 12 at 11:32
Russiancold
691315
1
Are you looking for Kind?
– Volker
Nov 12 at 11:45
@Volker As I said, I just want to ensure that key is a string
– Russiancold
Nov 12 at 11:50
add a comment |
I want to ensure that the type of map keys is string. Key() method returns Type and I'm not sure what is the right way to check if it's string. The only thing came to my mind is:
if v.Type().Key() == reflect.TypeOf("")
fmt.Print("It is string")
Is it the right way?
go reflection asked Nov 12 at 11:32
Russiancold
691315
I want to ensure that the type of map keys is string. Key() method returns Type and I'm not sure what is the right way to check if it's string. The only thing came to my mind is:
if v.Type().Key() == reflect.TypeOf("")
fmt.Print("It is string")
Is it the right way?
go reflection go reflection asked Nov 12 at 11:32
Russiancold
691315
asked Nov 12 at 11:32
Russiancold
691315
asked Nov 12 at 11:32
Russiancold
691315
asked Nov 12 at 11:32
Russiancold
691315
asked Nov 12 at 11:32
Russiancold
691315
691315
1
Are you looking for Kind?
– Volker
Nov 12 at 11:45
@Volker As I said, I just want to ensure that key is a string
– Russiancold
Nov 12 at 11:50
add a comment |
1
Are you looking for Kind?
– Volker
Nov 12 at 11:45
@Volker As I said, I just want to ensure that key is a string
– Russiancold
Nov 12 at 11:50
1
1
Are you looking for Kind?
– Volker
Nov 12 at 11:45
Are you looking for Kind?
– Volker
Nov 12 at 11:45
@Volker As I said, I just want to ensure that key is a string
– Russiancold
Nov 12 at 11:50
@Volker As I said, I just want to ensure that key is a string
– Russiancold
Nov 12 at 11:50
add a comment |
2 Answers
2
active
oldest
votes
Yes, what you did reports if the key type is "exactly" string.
But for example if the key type would be a custom type having string as its underlying type, like in this example:
type mystr string
m := map[mystr]int
Then the key type would not be equal to reflect.TypeOf("").
It's up to you if this is what you want. If you do want to accept the above map types too, you may check the kind of the key if it equals to reflect.String like this:
if v.Type().Key() == reflect.TypeOf("")
fmt.Print("It is string")
if v.Type().Key().Kind() == reflect.String
fmt.Print("It is string kind")
For the above map[mystr]int, this is the output (try it on the Go Playground):
It is string kind
(The key is not of type string, but it is of kind string.)
answered Nov 12 at 11:59
icza
161k24314354
Thanks, I've read about difference between type and kind.
– Russiancold
Nov 12 at 13:51
add a comment |
You can extract the Kind of the key and confront it with kind enumerations in reflect package like reflect.String as in:
package main
import (
"fmt"
"reflect"
)
func main()
obj := make(map[string]interface)
fmt.Println(reflect.TypeOf(obj).Key().Kind() == reflect.String) // It will print true
See this Go Playground snippet if you want to try it.
answered Nov 12 at 11:57
Vincenzo Maggio
3,1051939
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
Yes, what you did reports if the key type is "exactly" string.
But for example if the key type would be a custom type having string as its underlying type, like in this example:
type mystr string
m := map[mystr]int
Then the key type would not be equal to reflect.TypeOf("").
It's up to you if this is what you want. If you do want to accept the above map types too, you may check the kind of the key if it equals to reflect.String like this:
if v.Type().Key() == reflect.TypeOf("")
fmt.Print("It is string")
if v.Type().Key().Kind() == reflect.String
fmt.Print("It is string kind")
For the above map[mystr]int, this is the output (try it on the Go Playground):
It is string kind
(The key is not of type string, but it is of kind string.)
answered Nov 12 at 11:59
icza
161k24314354
Thanks, I've read about difference between type and kind.
– Russiancold
Nov 12 at 13:51
add a comment |
Yes, what you did reports if the key type is "exactly" string.
But for example if the key type would be a custom type having string as its underlying type, like in this example:
type mystr string
m := map[mystr]int
Then the key type would not be equal to reflect.TypeOf("").
It's up to you if this is what you want. If you do want to accept the above map types too, you may check the kind of the key if it equals to reflect.String like this:
if v.Type().Key() == reflect.TypeOf("")
fmt.Print("It is string")
if v.Type().Key().Kind() == reflect.String
fmt.Print("It is string kind")
For the above map[mystr]int, this is the output (try it on the Go Playground):
It is string kind
(The key is not of type string, but it is of kind string.)
answered Nov 12 at 11:59
icza
161k24314354
Thanks, I've read about difference between type and kind.
– Russiancold
Nov 12 at 13:51
add a comment |
Yes, what you did reports if the key type is "exactly" string.
But for example if the key type would be a custom type having string as its underlying type, like in this example:
type mystr string
m := map[mystr]int
Then the key type would not be equal to reflect.TypeOf("").
It's up to you if this is what you want. If you do want to accept the above map types too, you may check the kind of the key if it equals to reflect.String like this:
if v.Type().Key() == reflect.TypeOf("")
fmt.Print("It is string")
if v.Type().Key().Kind() == reflect.String
fmt.Print("It is string kind")
For the above map[mystr]int, this is the output (try it on the Go Playground):
It is string kind
(The key is not of type string, but it is of kind string.)
answered Nov 12 at 11:59
icza
161k24314354
Yes, what you did reports if the key type is "exactly" string.
But for example if the key type would be a custom type having string as its underlying type, like in this example:
type mystr string
m := map[mystr]int
Then the key type would not be equal to reflect.TypeOf("").
It's up to you if this is what you want. If you do want to accept the above map types too, you may check the kind of the key if it equals to reflect.String like this:
if v.Type().Key() == reflect.TypeOf("")
fmt.Print("It is string")
if v.Type().Key().Kind() == reflect.String
fmt.Print("It is string kind")
For the above map[mystr]int, this is the output (try it on the Go Playground):
It is string kind
(The key is not of type string, but it is of kind string.)
answered Nov 12 at 11:59
icza
161k24314354
edited Nov 12 at 13:51
answered Nov 12 at 11:59
icza
161k24314354
answered Nov 12 at 11:59
icza
161k24314354
answered Nov 12 at 11:59
icza
161k24314354
161k24314354
Thanks, I've read about difference between type and kind.
– Russiancold
Nov 12 at 13:51
add a comment |
Thanks, I've read about difference between type and kind.
– Russiancold
Nov 12 at 13:51
Thanks, I've read about difference between type and kind.
– Russiancold
Nov 12 at 13:51
Thanks, I've read about difference between type and kind.
– Russiancold
Nov 12 at 13:51
add a comment |
You can extract the Kind of the key and confront it with kind enumerations in reflect package like reflect.String as in:
package main
import (
"fmt"
"reflect"
)
func main()
obj := make(map[string]interface)
fmt.Println(reflect.TypeOf(obj).Key().Kind() == reflect.String) // It will print true
See this Go Playground snippet if you want to try it.
answered Nov 12 at 11:57
Vincenzo Maggio
3,1051939
add a comment |
You can extract the Kind of the key and confront it with kind enumerations in reflect package like reflect.String as in:
package main
import (
"fmt"
"reflect"
)
func main()
obj := make(map[string]interface)
fmt.Println(reflect.TypeOf(obj).Key().Kind() == reflect.String) // It will print true
See this Go Playground snippet if you want to try it.
answered Nov 12 at 11:57
Vincenzo Maggio
3,1051939
add a comment |
You can extract the Kind of the key and confront it with kind enumerations in reflect package like reflect.String as in:
package main
import (
"fmt"
"reflect"
)
func main()
obj := make(map[string]interface)
fmt.Println(reflect.TypeOf(obj).Key().Kind() == reflect.String) // It will print true
See this Go Playground snippet if you want to try it.
answered Nov 12 at 11:57
Vincenzo Maggio
3,1051939
You can extract the Kind of the key and confront it with kind enumerations in reflect package like reflect.String as in:
package main
import (
"fmt"
"reflect"
)
func main()
obj := make(map[string]interface)
fmt.Println(reflect.TypeOf(obj).Key().Kind() == reflect.String) // It will print true
See this Go Playground snippet if you want to try it.
answered Nov 12 at 11:57
Vincenzo Maggio
3,1051939
answered Nov 12 at 11:57
Vincenzo Maggio
3,1051939
answered Nov 12 at 11:57
Vincenzo Maggio
3,1051939
answered Nov 12 at 11:57
Vincenzo Maggio
3,1051939
3,1051939
add a comment |
add a comment |
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1
Are you looking for Kind?
– Volker
Nov 12 at 11:45
@Volker As I said, I just want to ensure that key is a string
– Russiancold
Nov 12 at 11:50