// Utility procedures and types to perform runtime type introspection/reflection (`RTTI`). // // WARNING! THIS IS ADVANCED BEHAVIOUR FOR ODIN! THIS SHOULD NOT BE USED BY BEGINNERS TO ODIN! // // This package is only to be used by individuals who know exactly how the RTTI works as well as EXACTLY how `any` works. // Especially since `any` can be unintuitive in its use to many, it can be dangerous to use. It is highly recommend that you **do not** // use `any` unless you know exactly what you are doing. // // RTTI is an extremely powerful tool which should only be used when absolutely necessary (such runtime-type-safe formatted printing). // // ## The Type System of Odin // // It is important to understand how the type systems works in Odin before using any RTTI. A good example of this is Odin's `distinct` type system. // In Odin, `distinct` types are represented by `Type_Info_Named`. A named struct is a `Type_Info_Named` which then points to a `Type_Info_Struct`. // This means you must use something like `type_info_base` to restrict the `Type_Info_Named` aspect and get the base-type directly. Doing a type-assertion // on the variant will not work as (incorrectly) expected without doing this. // // ## Advanced Information of How `any` Works // // An overview of how `any` works: // // An `any` type can reference any data type. It is functionally equivalent to `struct {data: rawptr, id: typeid}` with extra semantics on // how assignment and type assertion works. // // This is commonly used to construct runtime-type-safe printing, such as in `core:fmt`. // The use of `any` outside of this is heavily discourage and should be only used by people who FULLY understand its semantics. // // The `any` value is only valid as long as the underlying data is still valid. Passing a literal to an `any` will allocate the literal in // the current stack frame. // // Example: // x: int = 123 // a: any = x // // equivalent to // a: any // a.data = &x // a.id = typeid_of(type_of(x)) // // With literals // v: any = 123 // // equivalent to // v: any // _tmp: int = 123 // v.data = &_tmp // v.id = typeid_of(type_of(_tmp)) // // // `any` is a topologically-dual to a `union` in terms of its usage. Both support assignments of differing types // (`any` being open to any type, `union` being closed to a specific set of types), type assertions (`x.(T)`), and `switch in`. // The main internal difference is how the memory is stored. `any` being open is a pointer+typeid, a `union` // is a blob+tag. A `union` does not need to store a `typeid` because it is a closed ABI-consistent set of variant types. package reflect