This cheatsheet was written to support the reflective console article, available at PUT LINK HERE.
It’s duplicated here as a standalone reference.
| shorthand | type | obtained via |
|---|---|---|
| v | reflect.Value |
reflect.ValueOf("some string") |
| t | reflect.Type |
v.Type() or reflect.TypeOf("another string") |
| k | reflect.Kind |
t.Kind() |
| f | reflect.StructField |
t.Field() or t.FieldByName() or t.FieldByNameFunc() |
| n | int8..=int64 or int |
n := 2 |
| b | bool |
b := true |
| s | string or struct |
s := "some string", s := struct{foo int}{"foo} |
| m | map |
m := map[string]int{"a": 1} |
| a | slice or array |
a := []int{1, 2, 3} |
| function | description | example | analogous to |
ValueOf |
get a Value from an ordinary value |
reflect.ValueOf(int(2)) |
t := 2 |
||
TypeOf |
get a Type from the value |
t := reflect.TypeOf(int(2)) |
int |
||
| Type.Kind | get the underlying primitive type | t.Kind() |
int |
||
| — | — | — | — | ||
Type.ConvertibleTo |
can the type be converted to a different type? | t.ConvertibleTo(reflect.TypeOf(0)) |
|||
Value.Addr |
get the address of a value | v.Addr() |
&t |
||
Value.CanAddr |
can the value be addressed? | v.CanAddr() |
|||
Value.CanConvert |
can the value be converted to a different type? | v.CanConvert(reflect.TypeOf(0)) |
|||
Value.Convert |
convert a value to a different type | reflect.ValueOf(&t).Elem().Convert(reflect.TypeOf(b)) |
T(v) |
use | |
Value.Elem |
dereference a pointer or interface | v.Elem() |
*t |
||
Value.Field |
get the nth field of a struct |
v.Field(0) |
|||
Value.FieldByName |
for struct kinds, get the field with the given name |
v.FieldByName("someField") |
t.someField |
||
Value.FieldByNameFunc |
for struct kinds, get the field with the given name, matching the given predicate |
v.FieldByNameFunc(func(s string) bool { return strings.EqualFold(s, "somefield") }) |
s.someField or s.somefield or s.Somefield |
||
Value.Index |
for array and slice kinds, get the nth element |
v.Index(0) |
a[0] |
||
Value.Interface |
get an ordinary value back from a Value (as any) |
reflect.ValueOf(2).Interface().(int) |
any(int(2)).(int) |
||
Value.Len |
for array, map, and slice kinds, get the length |
v.Len() |
len(a), len(m) |
||
Value.MapIndex |
for map kinds, get the value associated with the given key |
v.MapIndex(reflect.ValueOf("someKey")) |
m["someKey"] |
||
Value.Set |
set lhs to rhs, if they’re the same Type |
v.Set(reflect.ValueOf(2)) |
t = 2 |