Concatenate String in LESS in loop

Question

I\'m working on converting Unsemantic from SASS to LESS and while I\'m building the loop to create my classes:

    .populateGridClasses (@index, @interval) w         


        

Answer 1

You could try passing another attribute to the mixin ... like this, where I added to your code the @t1 to the arguments and define the @t2 in the loop, and pass it on. Now you'll be writing to a variable only in the scope of one loop step, and not trying to overwrite the same variable over again in the recursion (does not agree with less). So this is your code, that should not get the error you mention anymore:

    @test: "";

    .populateGridClasses4 (@index, @interval, @t1) when (@index > 0) {
        @num: @index * @interval;
        @ntest: ".eh-grid-@{num}, .eh-mobile-grid-@{num}, .eh-tablet-grid-@{num}";
        @t2: ~"@{t1}@{ntest}";
    .populateGridClasses4(@index - 1, @interval,@t2);
    }

    .populateGridClasses4 (0, @interval,@t1) {}

    .populateGridClasses4(20, 5, @test);

    @{t2} {
        padding-left: 1px;
    }

Also you need use ~ for class interpolation, not to return the class names between quotation marks.

Edit: The above will only work in 1.3.3, but for your approach to work in 1.4 you need to tweak it a little. Also I noticed that the way you were joining the strings did not add commas between class names of each loop, so I added another step here, this should now do the right thing in1.4 and previous versions of LESS.

    .populateGridClasses4(1,@num,@t1) {
        @test: ~"@{t1}, .eh-grid-@{num}, .eh-mobile-grid-@{num}, .eh-tablet-grid-@{num}";
    }

    .populateGridClasses4(@index, @interval, @t1) when (@index > 1) {
        @num: (@index * @interval);
        @t2: "@{t1}, .eh-grid-@{num}, .eh-mobile-grid-@{num}, .eh-tablet-grid-@{num}";
        .populateGridClasses4((@index - 1),@interval,@t2);
    }

    .populateGridClasses4(@index,@interval) {
        @num: (@index * @interval);
        @t2: ".eh-grid-@{num}, .eh-mobile-grid-@{num}, .eh-tablet-grid-@{num}";
       .populateGridClasses4((@index - 1), @interval, @t2);
    }

    .populateGridClasses4(20, 5);
    @{test} { padding-left: 1px; }

the output CSS is:

  .eh-grid-100, .eh-mobile-grid-100, .eh-tablet-grid-100, .eh-grid-95, .eh-mobile-grid-95, .eh-tablet-grid-95, .eh-grid-90, .eh-mobile-grid-90, .eh-tablet-grid-90, .eh-grid-85, .eh-mobile-grid-85, .eh-tablet-grid-85, .eh-grid-80, .eh-mobile-grid-80, .eh-tablet-grid-80, .eh-grid-75, .eh-mobile-grid-75, .eh-tablet-grid-75, .eh-grid-70, .eh-mobile-grid-70, .eh-tablet-grid-70, .eh-grid-65, .eh-mobile-grid-65, .eh-tablet-grid-65, .eh-grid-60, .eh-mobile-grid-60, .eh-tablet-grid-60, .eh-grid-55, .eh-mobile-grid-55, .eh-tablet-grid-55, .eh-grid-50, .eh-mobile-grid-50, .eh-tablet-grid-50, .eh-grid-45, .eh-mobile-grid-45, .eh-tablet-grid-45, .eh-grid-40, .eh-mobile-grid-40, .eh-tablet-grid-40, .eh-grid-35, .eh-mobile-grid-35, .eh-tablet-grid-35, .eh-grid-30, .eh-mobile-grid-30, .eh-tablet-grid-30, .eh-grid-25, .eh-mobile-grid-25, .eh-tablet-grid-25, .eh-grid-20, .eh-mobile-grid-20, .eh-tablet-grid-20, .eh-grid-15, .eh-mobile-grid-15, .eh-tablet-grid-15, .eh-grid-10, .eh-mobile-grid-10, .eh-tablet-grid-10, .eh-grid-5, .eh-mobile-grid-5, .eh-tablet-grid-5 {
    padding-left: 1px;
  }