std/typeinfo

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This module implements an interface to Nim's runtime type information (RTTI). See the marshal module for an example of what this allows you to do.

Note: Even though Any and its operations hide the nasty low level details from its users, it remains inherently unsafe! Also, Nim's runtime type information will evolve and may eventually be deprecated. As an alternative approach to programmatically understanding and manipulating types, consider using the macros module to work with the types' AST representation at compile time. See for example the getTypeImpl proc. As an alternative approach to storing arbitrary types at runtime, consider using generics.

Example:

import std/typeinfo
var x: Any

var i = 42
x = i.toAny
assert x.kind == akInt
assert x.getInt == 42

var s = @[1, 2, 3]
x = s.toAny
assert x.kind == akSequence
assert x.len == 3

Types

AnyKind = enum
  akNone = 0,               ## invalid
  akBool = 1,               ## bool
  akChar = 2,               ## char
  akEnum = 14,              ## enum
  akArray = 16,             ## array
  akObject = 17,            ## object
  akTuple = 18,             ## tuple
  akSet = 19,               ## set
  akRange = 20,             ## range
  akPtr = 21,               ## ptr
  akRef = 22,               ## ref
  akSequence = 24,          ## sequence
  akProc = 25,              ## proc
  akPointer = 26,           ## pointer
  akString = 28,            ## string
  akCString = 29,           ## cstring
  akInt = 31,               ## int
  akInt8 = 32,              ## int8
  akInt16 = 33,             ## int16
  akInt32 = 34,             ## int32
  akInt64 = 35,             ## int64
  akFloat = 36,             ## float
  akFloat32 = 37,           ## float32
  akFloat64 = 38,           ## float64
  akFloat128 = 39,          ## float128
  akUInt = 40,              ## uint
  akUInt8 = 41,             ## uint8
  akUInt16 = 42,            ## uin16
  akUInt32 = 43,            ## uint32
  akUInt64 = 44              ## uint64
The kind of Any.   Source   Edit
Any = object
  value: pointer
  when defined(js):
      rawType: PNimType

  else:
      rawTypePtr: pointer

  
A type that can represent any nim value.
Danger: The wrapped value can be modified with its wrapper! This means that Any keeps a non-traced pointer to its wrapped value and must not live longer than its wrapped value.
  Source   Edit

Procs

proc toAny[T](x: var T): Any {.inline.}
Constructs an Any object from x. This captures x's address, so x can be modified with its Any wrapper! The caller needs to ensure that the wrapper does not live longer than x!   Source   Edit
proc kind(x: Any): AnyKind {.inline, ...raises: [], tags: [].}
Gets the type kind.   Source   Edit
proc size(x: Any): int {.inline, ...raises: [], tags: [].}
Returns the size of x's type.   Source   Edit
proc baseTypeKind(x: Any): AnyKind {.inline, ...raises: [], tags: [].}
Gets the base type's kind. If x has no base type, akNone is returned.   Source   Edit
proc baseTypeSize(x: Any): int {.inline, ...raises: [], tags: [].}
Returns the size of x's base type. If x has no base type, 0 is returned.   Source   Edit
proc invokeNew(x: Any) {....raises: [], tags: [].}
Performs new(x). x needs to represent a ref.   Source   Edit
proc invokeNewSeq(x: Any; len: int) {....raises: [], tags: [].}
Performs newSeq(x, len). x needs to represent a seq.   Source   Edit
proc extendSeq(x: Any) {....raises: [], tags: [].}
Performs setLen(x, x.len+1). x needs to represent a seq.   Source   Edit
proc setObjectRuntimeType(x: Any) {....raises: [], tags: [].}
This needs to be called to set x's runtime object type field.   Source   Edit
proc `[]`(x: Any; i: int): Any {....raises: [ValueError], tags: [].}
Accessor for an any x that represents an array or a sequence.   Source   Edit
proc `[]=`(x: Any; i: int; y: Any) {....raises: [ValueError], tags: [].}
Accessor for an any x that represents an array or a sequence.   Source   Edit
proc len(x: Any): int {....raises: [], tags: [].}
len for an any x that represents an array or a sequence.   Source   Edit
proc base(x: Any): Any {....raises: [], tags: [].}
Returns the base type of x (useful for inherited object types).   Source   Edit
proc isNil(x: Any): bool {....raises: [], tags: [].}
isNil for an x that represents a cstring, proc or some pointer type.   Source   Edit
proc getPointer(x: Any): pointer {....raises: [], tags: [].}
Retrieves the pointer value out of x. x needs to be of kind akString, akCString, akProc, akRef, akPtr, akPointer or akSequence.   Source   Edit
proc setPointer(x: Any; y: pointer) {....raises: [], tags: [].}
Sets the pointer value of x. x needs to be of kind akString, akCString, akProc, akRef, akPtr, akPointer or akSequence.   Source   Edit
proc `[]=`(x: Any; fieldName: string; value: Any) {....raises: [ValueError],
    tags: [].}
Sets a field of x. x needs to represent an object or a tuple.   Source   Edit
proc `[]`(x: Any; fieldName: string): Any {....raises: [ValueError], tags: [].}
Gets a field of x. x needs to represent an object or a tuple.   Source   Edit
proc `[]`(x: Any): Any {....raises: [], tags: [].}
Dereference operator for Any. x needs to represent a ptr or a ref.   Source   Edit
proc `[]=`(x, y: Any) {....raises: [], tags: [].}
Dereference operator for Any. x needs to represent a ptr or a ref.   Source   Edit
proc getInt(x: Any): int {....raises: [], tags: [].}
Retrieves the int value out of x. x needs to represent an int.   Source   Edit
proc getInt8(x: Any): int8 {....raises: [], tags: [].}
Retrieves the int8 value out of x. x needs to represent an int8.   Source   Edit
proc getInt16(x: Any): int16 {....raises: [], tags: [].}
Retrieves the int16 value out of x. x needs to represent an int16.   Source   Edit
proc getInt32(x: Any): int32 {....raises: [], tags: [].}
Retrieves the int32 value out of x. x needs to represent an int32.   Source   Edit
proc getInt64(x: Any): int64 {....raises: [], tags: [].}
Retrieves the int64 value out of x. x needs to represent an int64.   Source   Edit
proc getBiggestInt(x: Any): BiggestInt {....raises: [], tags: [].}
Retrieves the integer value out of x. x needs to represent some integer, a bool, a char, an enum or a small enough bit set. The value might be sign-extended to BiggestInt.   Source   Edit
proc setBiggestInt(x: Any; y: BiggestInt) {....raises: [], tags: [].}
Sets the integer value of x. x needs to represent some integer, a bool, a char, an enum or a small enough bit set.   Source   Edit
proc getUInt(x: Any): uint {....raises: [], tags: [].}
Retrieves the uint value out of x. x needs to represent a uint.   Source   Edit
proc getUInt8(x: Any): uint8 {....raises: [], tags: [].}
Retrieves the uint8 value out of x. x needs to represent a uint8.   Source   Edit
proc getUInt16(x: Any): uint16 {....raises: [], tags: [].}
Retrieves the uint16 value out of x. x needs to represent a uint16.   Source   Edit
proc getUInt32(x: Any): uint32 {....raises: [], tags: [].}
Retrieves the uint32 value out of x. x needs to represent a uint32.   Source   Edit
proc getUInt64(x: Any): uint64 {....raises: [], tags: [].}
Retrieves the uint64 value out of x. x needs to represent a uint64.   Source   Edit
proc getBiggestUint(x: Any): uint64 {....raises: [], tags: [].}
Retrieves the unsigned integer value out of x. x needs to represent an unsigned integer.   Source   Edit
proc setBiggestUint(x: Any; y: uint64) {....raises: [], tags: [].}
Sets the unsigned integer value of x. x needs to represent an unsigned integer.   Source   Edit
proc getChar(x: Any): char {....raises: [], tags: [].}
Retrieves the char value out of x. x needs to represent a char.   Source   Edit
proc getBool(x: Any): bool {....raises: [], tags: [].}
Retrieves the bool value out of x. x needs to represent a bool.   Source   Edit
proc skipRange(x: Any): Any {....raises: [], tags: [].}
Skips the range information of x.   Source   Edit
proc getEnumOrdinal(x: Any; name: string): int {....raises: [], tags: [].}
Gets the enum field ordinal from name. x needs to represent an enum but is only used to access the type information. In case of an error low(int) is returned.   Source   Edit
proc getEnumField(x: Any; ordinalValue: int): string {....raises: [], tags: [].}
Gets the enum field name as a string. x needs to represent an enum but is only used to access the type information. The field name of ordinalValue is returned.   Source   Edit
proc getEnumField(x: Any): string {....raises: [], tags: [].}
Gets the enum field name as a string. x needs to represent an enum.   Source   Edit
proc getFloat(x: Any): float {....raises: [], tags: [].}
Retrieves the float value out of x. x needs to represent a float.   Source   Edit
proc getFloat32(x: Any): float32 {....raises: [], tags: [].}
Retrieves the float32 value out of x. x needs to represent a float32.   Source   Edit
proc getFloat64(x: Any): float64 {....raises: [], tags: [].}
Retrieves the float64 value out of x. x needs to represent a float64.   Source   Edit
proc getBiggestFloat(x: Any): BiggestFloat {....raises: [], tags: [].}
Retrieves the float value out of x. x needs to represent some float. The value is extended to BiggestFloat.   Source   Edit
proc setBiggestFloat(x: Any; y: BiggestFloat) {....raises: [], tags: [].}
Sets the float value of x. x needs to represent some float.   Source   Edit
proc getString(x: Any): string {....raises: [], tags: [].}
Retrieves the string value out of x. x needs to represent a string.   Source   Edit
proc setString(x: Any; y: string) {....raises: [], tags: [].}
Sets the string value of x. x needs to represent a string.   Source   Edit
proc getCString(x: Any): cstring {....raises: [], tags: [].}
Retrieves the cstring value out of x. x needs to represent a cstring.   Source   Edit
proc assign(x, y: Any) {....raises: [], tags: [].}
Copies the value of y to x. The assignment operator for Any does NOT do this; it performs a shallow copy instead!   Source   Edit
proc inclSetElement(x: Any; elem: int) {....raises: [], tags: [].}
Includes an element elem in x. x needs to represent a Nim bitset.   Source   Edit

Iterators

iterator fields(x: Any): tuple[name: string, any: Any] {....raises: [], tags: [].}
Iterates over every active field of x. x needs to represent an object or a tuple.   Source   Edit
iterator elements(x: Any): int {....raises: [], tags: [].}
Iterates over every element of x. x needs to represent a set.   Source   Edit