Module marshal

This module contains procs for serialization and deseralization of arbitrary Nim data structures. The serialization format uses JSON. Warning: The serialization format could change in future!

Restriction: For objects their type is not serialized. This means essentially that it does not work if the object has some other runtime type than its compiletime type:

type
  A = object of RootObj
  B = object of A
    f: int

var
  a: ref A
  b: ref B

new(b)
a = b
echo($$a[]) # produces "{}", not "{f: 0}"

# unmarshal
let c = to[B]("""{"f": 2}""")

# marshal
let s = $$c

Note: The to and $$ operations are available at compile-time!

Imports

streams, typeinfo, json, intsets, tables, unicode

Procs

proc load[T](s: Stream; data: var T)

loads data from the stream s. Raises EIO in case of an error.

proc store[T](s: Stream; data: T)

stores data into the stream s. Raises EIO in case of an error.

proc `$$`[T](x: T): string

returns a string representation of x.

Note: to serialize x to JSON use $(%x) from the json module

proc to[T](data: string): T

reads data and transforms it to a T.

Examples:

type
  Foo = object
    id: int
    bar: string

let x = Foo(id: 1, bar: "baz")
let y = ($$x)
let z = to[Foo](y)