@warn

@warn

The @warn directive prints the value of a SassScript expression to the standard error output stream. It’s useful for libraries that need to warn users of deprecations or recovering from minor mixin usage mistakes. There are two major distinctions between @warn and @debug:

1. You can turn warnings off with the --quiet command-line option or the :quiet Sass option.
2. A stylesheet trace will be printed out along with the message so that the user being warned can see where their styles caused the warning.

Usage Example:

@mixin adjust-location($x, $y) {
  @if unitless($x) {
    @warn "Assuming #{$x} to be in pixels";
    $x: 1px * $x;
  }
  @if unitless($y) {
    @warn "Assuming #{$y} to be in pixels";
    $y: 1px * $y;
  }
  position: relative; left: $x; top: $y;
}