SASS / SCSS: Interpolate variable from string / name - variables

Question

Is it possible to get a variable by name?
I tried building the following function, but it's not working as expected...
#function variable-lookup($variable, $suffix: "") {
$value: null;
#if ($suffix != "" and global-variable-exists($variable+"-"+$suffix)) {
$value: #{$variable+"-"+$suffix};
}
#else if (global-variable-exists($variable)) {
$value: #{$variable};
}
#return $value;
}
Here's an example of how it might be used:
$primary: #000;
$primary-hover: blue;
a {
color: variable-lookup("primary", "base");
&:hover {
color: variable-lookup("primary", "hover");
}
}
The real power would come in when I want to write a bunch of context-specific, shorthand wrapper functions around this "variable-lookup" function.
Any ideas how to achieve this?

Answer 1

Trying to interpolate #{$variable+"-"+$suffix} to give the value primary-base and further trying to get the value of same variable name is not possible. primary-base is already a value and and can't be interpreted as a variable name. That sort of thing could lead to a lot of chaos.
For what you want to accomplish, you are better of using a map and checking for the key in that map
$colours: (
'primary': red,
'primary-base': blue
);
#function variable_lookup($colour, $suffix: '') {
$value: null;
#if ( $suffix != '' and map-has-key($colours, unquote($colour+'-'+$suffix)) ) {
$value: map-get($colours, unquote($colour+'-'+$suffix));
} #else if ( map-has-key($colours, unquote($colour)) ) {
$value: map-get($colours, unquote($colour));
}
#return $value;
}
div {
color: variable-lookup(primary, base);
}
p {
color: variable-lookup(primary);
}
This compiles to the following css
div {
color: blue; }
p {
color: red; }
Your code stored colours as variables but I used those names as keys in maps
This allowed to simulate the checking of variables in your code using the map-has-key method. If that returns true, the key exists and we can get the value which in this case would be the colour using map-get
UPDATED ANSWER
One way to address the issues you raised in your comments would be to define the variables and use them in as values in the map
$primary: #fff;
$warning: yellow;
$colours: ( primary: $primary,
primary-hover: darken($primary, 5%),
secondary: $warning,
secondary-hover: darken($warning, 5%) );
Another way would be to iterate through two lists and map colour to a style
$colours: ();
$list: primary success warning; //map primary to blue, success to green and so on
$shades: blue green yellow;
#for $i from 1 through length($list) {
$key: nth($list, $i);
$value: nth($shades, $i);
$colours: map-merge($colours, ($key: $value));
$colours: map-merge($colours, (unquote($key+'-hover'): darken($value, 5% )) );
}
#debug $colours // (primary: blue, primary-hover: #0000e6, success: green, success-hover: #006700, warning: yellow, warning-hover: #e6e600)
The variable_lookup function remains the same.
Hope this is able to help