Can I declare a new variable inside a SASS mixin? [duplicate]

Question

I have the following SASS mixin:

@mixin gradient($start, $end, $fallback: $end, $direction: bottom) {
@if $direction == top {
    $directionOld: bottom;
} @else if $direction == right {
    $directionOld: left;
} @elseif $direction == bottom {
    $directionOld: top;
} @elseif $direction == left {
    $directionOld: right;
}

background: $fallback;
background: -webkit-linear-gradient($directionOld, $start, $end);
background:         linear-gradient(to $direction, $start, $end);
}

This mixin throws an error because $directionOld is not defined. I can fix it adding this variable by default to the mixin params:

@mixin gradient($start, $end, $fallback: $end, $direction: bottom, $directionOld: top) {
@if $direction == top {
    $directionOld: bottom;
} @else if $direction == right {
    $directionOld: left;
} @elseif $direction == bottom {
    $directionOld: top;
} @elseif $direction == left {
    $directionOld: right;
}

background: $fallback;
background: -webkit-linear-gradient($directionOld, $start, $end);
background:         linear-gradient(to $direction, $start, $end);
}

But this is not as clean as I want, is there any error in the first code?

Thank you so much!

Answer 1

Yes you can define new variable in Mixin but you have to define it before use it in an if statement.

I write your code again:

@mixin gradient($start, $end, $fallback: $end, $direction: bottom) {
    $directionOld:top !default;

    @if $direction == top {
        $directionOld: bottom;
    } @else if $direction == right {
        $directionOld: left;
    } @elseif $direction == bottom {
        $directionOld: top;
    } @elseif $direction == left {
        $directionOld: right;
    }

    background: $fallback;
    background: -webkit-linear-gradient($directionOld, $start, $end);
    background:         linear-gradient(to $direction, $start, $end);
}