Creating a sass map value from within a mixin - saved globally [duplicate] - sass

Question

This question already has answers here:
How to assign to a global variable in Sass?
(2 answers)
Closed 6 years ago.
Is it possible to update a value in a sass map from within a mixin so that the change is saved globally?
Eg
$obj: (
init: false
)
#mixin set($map) {
#if map-get($obj, init) != true {
// mixin hasn't been called before
$map: map-set($map, init, true);
}
#else {
// mixin has been called before
}
}
.test {
#include set($obj);
// sets the init value to true
}
.test-2 {
#include set($obj);
// init value has already been set to true
}

Answer 1

I'm not sure if I understood what you are trying to do, but your code seems to be fine (haven't tested it though), excepting that there is no map-set function, but you can create one or just use map-merge (check here: http://oddbird.net/2013/10/19/map-merge/). I hope that helps.
#update 1: I think I got your question now, you want to pass the reference through the mixin, so if you have multiple maps, you can send the one you want to update to the mixin, I don't think this is possible though, because no reference is kept, if you need to update the variable you have to link directly to it, for exemple, this works (tested):
$obj: (
init: false
);
#mixin set($map) {
#if map_get($map, init) != true {
$obj: map-set($map, init, true) !global;
body {
background-color: #000;
}
} #else {
body {
background-color: #ff0000;
}
}
}
#include set($obj);
#include set($obj);
But if you reference to $map instead of $obj (in this line $obj: map-set($map, init, true) !global;), then a new global map (called $map), will be created. And every time you call the mixin again, it will be replaced by the map you sent as a parameter.
#update 2: I found a way to do it, but you have to keep a global 'map of maps', and every time you update this guy, you send the name of the map you want to update as parameter, so I came up with the following code, it's tested and working fine :)
#function map-set($map, $key, $value) {
$new: ($key: $value);
#return map-merge($map, $new);
}
$maps: (
obj1: (
init: false
),
obj2: (
init: false
),
);
#mixin set($prop) {
#if map_get(map_get($maps, $prop), init) != true {
$obj: map-set(map_get($maps, $prop), init, true);
$maps: map-set($maps, $prop, $obj) !global;
body {
background-color: #000;
}
} #else {
body {
background-color: #ff0000;
}
}
}
#include set(obj1); //black
#include set(obj2); //black
#include set(obj1); //red
#include set(obj2); //red
source: myself

Answer 2

Following on from #Paulo Munoz
Here is the solution
#function map-set($map, $key, $value) {
$new: ($key: $value);
#return map-merge($map, $new);
}
$extend : ();
$obj : (
margin: 0,
padding: 10
);
#mixin set($map, $name) {
#if map-has-key($extend, $name) {
map: has-key;
// call placeholder class
} #else {
$extend: map-set($extend, $name, true) !global;
map: does-not-have-key;
// create placeholder class
// call placeholder class
}
}
.test {
#include set($obj, test);
}
.test-2 {
#include set($obj, test);
}
which generates
.test {
map: does-not-have-key;
}
.test-2 {
map: has-key;
}