scss\sass calc 的mixin&include 处理方法

How can I create a calc mixin to pass as an expression to generate tags?

CSS3的calc()使用

@mixin calc($property, $expression) { 
  #{$property}: -webkit-calc(#{$expression}); 
  #{$property}: calc(#{$expression}); 
} 

.test {
  @include calc(width, "25% - 1em");
} 

Will render as

.test { 
    width: -webkit-calc(25% - 1em); 
    width: calc(25% - 1em);
}