LESS mixin recursion error to convert pixels to rems

Question

I am trying to make a mixin to propery convert pixels to relative ems. I would like it to be flexible enough to allow any property to be used with any number of pixel values.

Any ideas on how to add multiple values to a single property without the recursion error I'm creating inside the for loop?

desired usage example 1:

.pixels-to-rems(font-size; 10);

desired output:

font-size: 10px;
font-size: 1rem;

desired usage example 2:

.pixels-to-rems(padding; 10,0,20,10);

desired output:

padding: 10px, 0px, 20px, 10px;
padding: 1rem, 0px, 2rem, 1rem;

Here's the mixin as is.

@baseFontSize: 10px;
.pixels-to-rems(@property, @pxvals) {
    @pxValue: null;
    @remValue: null;

    .for(@pxvals); .-each(@pxval) {
        @pxValue: @pxValue @pxval;
        @remValue: @remValue (@pxval / @baseFontSize);
    }

    @{property}: ~"@{pxValue}px";
    @{property}: ~"@{remValue}rem";
}

.for() mixin found here

Answer 1

See Merge feature. The only trick is that the merge statement will concatenate values into the same property rule, thus you'll have to isolate px and rem rules via some hack. For example like this:

usage {
    .pixels-to-rems(padding, 10 0 20 10);
    .pixels-to-rems(font-size, 50);
}

// impl.:

@base-font-size: 10px;

.pixels-to-rems(@p, @vs) {
    .for(@vs); .-each(@v) {
        @{p}+_:     1px  * @v;
        @{p}@{-}+_: 1rem * @v / @base-font-size;
    }
    @-: ~" ";
}

// .for-each impl. (stripped from the snipped linked in the question)

.for(@array)                 {.for-impl_(length(@array))}
.for-impl_(@i) when (@i > 1) {.for-impl_((@i - 1))}
.for-impl_(@i) when (@i > 0) {.-each(extract(@array, @i))}

Demo.