The difference in these two constructs is that, for an expression foo of static (declared or inferred) type Foo: foo.javaClass is typed as Class<Foo> foo::class.java is typed as Class<out Foo> In fact, the latter is more precise, because the actual value that foo evaluates to can be an instance of not Foo itself but one … Read more
This should work: typedefof<System.IEnumerable<_>> EDIT As Tomas notes, there’s nothing special about the _ wildcard here; F# infers that the type obj is the most general applicable type in this context, so this is the same as using typedefof<System.IEnumerable<obj>>. In some cases the way this works can be a bit of a hindrance, though. For … Read more
A good example of how to parse values is the fmt package. See this code. Using the mentioned code to match your problem would look like this: switch val.Kind() { case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64: m[typeField.Name] = strconv.FormatInt(val.Int(), 10) case reflect.String: m[typeField.Name] = val.String() // etc… } Basically you need to check for all … Read more
You don’t need to pass in the whole struct, but passing in the value of one of the fields is not sufficient. In your example user.name field is just a string – the reflect package will have no way of correlating that back to the original struct. Instead, you need to pass around the reflect.StructField … Read more
dump() For example println “ddd”.dump() Prints: java.lang.String@2ef900 value=dddd offset=0 count=4 hash=3078400
There is an easier way to invoke method reflectively without resorting to calling Java reflection methods: use Structural Typing. Just cast the object reference to a Structural Type which has the necessary method signature then call the method: no reflection necessary (of course, Scala is doing reflection underneath but we don’t need to do it). … Read more
concreteCat,_ := reflect.ValueOf(cat).Interface().(Cat) see http://golang.org/doc/articles/laws_of_reflection.html fox example type MyInt int var x MyInt = 7 v := reflect.ValueOf(x) y := v.Interface().(float64) // y will have type float64. fmt.Println(y)
The Wikipedia article has a pretty decent summary: In computing, type introspection is the ability of a program to examine the type or properties of an object at runtime. Some programming languages possess this capability. Introspection should not be confused with reflection, which goes a step further and is the ability for a program to … Read more
Reflection is most commonly used to circumvent the static type system, however it also has some interesting use cases: Let’s write an ORM! If you’re familiar with NHibernate or most other ORMs, you write classes which map to tables in your database, something like this: // used to hook into the ORMs innards public class … Read more
First of all, Rust doesn’t have reflection; reflection implies you can get details about a type at runtime, like the fields, methods, interfaces it implements, etc. You can not do this with Rust. The closest you can get is explicitly implementing (or deriving) a trait that provides this information. Each type gets a TypeId assigned … Read more