Go language provides inbuilt support implementation of run-time reflection and allowing a program to manipulate objects with arbitrary types with the help of reflect package. The reflect.CanSet() Function in Golang is used to check whether the value of v can be changed. To access this function, one needs to imports the reflect package in the program.
Syntax:
func (v Value) CanSet() boolParameters: This function does not accept any parameters.
Return Value: This function returns the boolean value.
Below examples illustrate the use of above method in Golang:
Example 1:
// Golang program to illustrate // reflect.CanSet() Function package main import ( "reflect"
"fmt"
) type ProductionInfo struct {
StructA []Entry
} type Entry struct {
Field1 string
Field2 int
} func SetField(source interface{}, fieldName string, fieldValue string){ v := reflect.ValueOf(source)
tt := reflect.TypeOf(source)
for k := 0; k < tt.NumField(); k++ {
fieldValue := reflect.ValueOf(v.Field(k))
// use of CanSet() method
fmt.Println(fieldValue.CanSet())
if fieldValue.CanSet(){
fieldValue.SetString(fieldValue.String())
}
}
} // Main function func main() { source := ProductionInfo{}
source.StructA = append(source.StructA, Entry{Field1: "A" , Field2: 2})
SetField(source, "Field1" , "NEW_VALUE" )
} |
Output:
false
Example 2:
// Golang program to illustrate // reflect.CanSet() Function package main import ( "fmt"
"reflect"
) type ProductionInfo struct {
StructA []Entry
} type Entry struct {
Field1 string
Field2 int
} func SetField(source interface{}, fieldName string, fieldValue string) { v := reflect.ValueOf(source).Elem()
// use of CanSet() method
fmt.Println(v.FieldByName(fieldName).CanSet())
if v.FieldByName(fieldName).CanSet() {
v.FieldByName(fieldName).SetString(fieldValue)
}
} // Main function func main() { source := ProductionInfo{}
source.StructA = append(source.StructA, Entry{Field1: "A" , Field2: 2})
fmt.Println( "Before: " , source.StructA[0])
SetField(&source.StructA[0], "Field1" , "NEW_VALUE" )
fmt.Println( "After: " , source.StructA[0])
} |
Output:
Before: {A 2} true After: {NEW_VALUE 2}
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