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Map module (map)

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map::Map is a string-keyed, dynamic-value map: keys are str, and values are stored in the language's dynamic representation, so you can store numbers, text, and other values under different keys. Add bring map, then new map::Map().

A tiny program​

bring map

var m: map::Map = new map::Map()
m.set("a", 1)
m.set("b", "two")
println(m.get("a"))
println(m.get("b"))
println(m.size())

Output:

1
two
2

Typical uses: small JSON-like in-memory data, config keyed by name, and caches in scripts.

Common operations (cheat sheet)​

  • Read / write — get, getOr, set, insert (alias for set)
  • Structure — has, contains (alias for has), remove, size, isEmpty, clear

More examples​

Using getOr with a fallback​

bring map

var m: map::Map = new map::Map()
m.set("x", 42)

var a = m.getOr("x", 0)
var b = m.getOr("missing", 0)
println(a)
println(b)

Output:

42
0

Checking keys with has, removing entries, and clearing​

bring map

var m: map::Map = new map::Map()
m.set("key1", "value1")
m.set("key2", "value2")

println(m.has("key1"))
println(m.remove("key1"))
println(m.has("key1"))
println(m.size())

m.clear()
println(m.size())
println(m.isEmpty())

Output:

true
true
false
1
0
true

Iteration over keys​

Use a vec::Vec as a sidecar to track inserted keys, then iterate with a for-loop:

bring map
bring vec

var m: map::Map = new map::Map()
var keys: vec::Vec = new vec::Vec()

m.set("a", 1)
keys.push("a")
m.set("b", 2)
keys.push("b")
m.set("c", 3)
keys.push("c")

for (var i: int = 0 to keys.size() - 1 : 1) {
  var k = keys.get(i)
  println(k, " = ", m.get(k))
}

Output:

a = 1
b = 2
c = 3

More detail: keys, values, and dyn​

Map stores values with the dyn-style value model for heterogeneous storage. For type-safe fixed shapes, the language's type, objects, and classes are often a better long-term design than a single unbounded map; use Map when flexibility matters more.

Source & tests (if you have the repository)​

WhatWhere
Module source (reference)fw-modules/map_module/map-module.fg.
Integration-style fixturestests/fixtures/LatestTests/MapModuleTests/.