scottkellum/OOSass.md

## OOSass.md

      
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              OOSass.md
            
          
    OOCSS vs OOSass

note that this requires Sass 3.2 alpha or higher

OOCSS is awesome because it helps us organize our style sheets in clean and simple ways but it can be far too rigid for the new responsive web. How can we use preprocessors to preserve both flexibility and cleanliness of code? Can these objects be abstracted to our preprocessors?
Lets first take a look at three column widths in OOCSS to see how they compare.
CSS
.width-1 {
  width: 100px;
}
.width-2 {
  width: 200px;
}
.width-3 {
  width: 300px;
}
HTML
<aside class="width-1">
But why am I writing .width-2 and .width-3 if I am not using them? I also have the layout class applied directly to my HTML. Do I add more classes as I add more CSS for breakpoints?
How can OOSass solve these issues?
Sass
%width-1 {
  width: 100px;
}
%width-2 {
  width: 200px;
}
%width-3 {
  width: 300px;
}

aside {
  @extend %width-1;
}
Compiled CSS
aside {
  width: 100px;
}
HTML
<aside>
Adding intelligence

Clean right? And you can simply build on to classes and names that describe the content instead of adding rigid layout classes to your markup. But we can also use Sass to add intelligence to the code being written. Chances are, you want space between these elements. Lets add 10px gutters but we are using Sass, let it figure out where the columns are.
$column: 100px;
$gutter: 10px;

%column {
  float: left;
}

%next-column {
  margin-left: $gutter;
}

%width-1 {
  width: $column;
}
%width-2 {
  width: $column * 2;
}
%width-3 {
  width: $column * 3;
}

article {
  @extend %width-2;
  @extend %column;
}

aside {
  @extend %width-1;
  @extend %column;
  @extend %next-column;
}
Now we added more classes to flush out the functionality but we have to write a lot of objects and we have to figure out where we are each time. Sass can take care of this for you by simply counting what column you are on.
$counter: 0;

@mixin width($width) {
  @if $counter >= 3 { // if the counter is less than or equal to our total number of columns
    $counter: 0; // reset the counter to zero
  }
  
  // Write our conditions
  @extend %width-#{$width};
  @extend %column;
  
  // If we are not starting on the first column, extend the next-column object
  @if $counter != 0 {
    @extend %next-column;
  }
  
  // Add the width to the counter so we know what column is next
  $counter: $counter + $width;
}
This mixin keeps track of what column we are on and will extend the appropriate objects. Now all we need to do is include how wide we want our columns and Sass will figure out where we are on the grid and accommodate for that.
article {
  @include width(2);
}

aside {
  @include width(1);
}
Now if you are already familiar with Sass you know that you could write a loop to set any number of columns at any number of sizes. But this is a simple example of what can be done with OOSass.