Create an object/Native demonstration: Difference between revisions

=={{header|Nim}}==

We leverage native stdlib table as our own object by implementing limited actual native table functionalities.

<lang nim>import tables, options

type

MyTable = object

table: TableRef[string, int]

# return empty if the key is not available

proc `[]`(m: MyTable, key: string): Option[int] =

if key in m.table: result = some m.table[key]

else: result = none int

# update an item, doing nothing if the key is available during first initialization

proc `[]=`(m: var MyTable, key: string, val: int) =

if key notin m.table: return

m.table[key] = val

proc reset(m: var MyTable) =

for _, v in m.table.mpairs: v = 0

# sugar for defining MyTable object

proc toTable(vals: openarray[(string, int)]): MyTable =

result.table = newTable vals

proc main =

# MyTable construction

var myobj = {"key1": 1, "key2": 2, "key3": 3}.toTable

# test getting existing key

let val1 = myobj["key1"]

if val1.isSome: echo "val1: ", val1.get

# test adding new key

myobj["key4"] = 4

let val4 = myobj["key4"]

if val4.isSome: echo val4.get

else: echo "val4 is empty"

# test reset and test whether its value is zero-ed

reset myobj

doAssert myobj["key3"].get == 0

main()

</lang>

{{output}}

<pre>

val1: 1

val4 is empty</pre>