SASS 中如何写IE7 hack

初次尝试SASS,遇到hack问题，再次记下点滴。

原先代码：

#yzm{ +display: inline;}

　　报错提示：

Syntax error: Invalid CSS after "...+display:inline": expected "{", was ";"
        on line 31 of D:\root\wwwdemo\test\wtd\caigou\style.scss
  Use --trace for backtrace.

　　解决方案：

$hack_ie7：'+';
#yzm{ #{$hack_ie7}display: inline; }

　　其他参考：（我没看懂，希望有看到的人懂的帮下解释下，我猜大致是传参执行方法的意思）

// Visible for IE <= 7
=ie7-hack($property, $ie7-value)
  ##{$property}: #{$ie7-value}

// Visible for IE <= 6
=ie6-hack($property, $ie6-value)
  _#{$property}: #{$ie6-value}

// this mixin has to be called last due to its usage of the ie8-hack mixin usage
=gt-ie6-hack($property, $value)
  +ie7-hack($property, $value)
  +ie8-hack($property, $value)

// Visible for IE = 8
// this mixin has to be called last
// @see: http://dimox.net/personal-css-hacks-for-ie6-ie7-ie8/
=ie8-hack($property, $ie8-value)
  #{$property}: #{$ie8-value}#{"\0/"}

// Allows to apply horizontal padding for buttons
// @see: http://www.mrkirkland.com/internet-explorer-submit-button-horizontal-padding/
=ie7-button-fix
  +ie7-hack('overflow', 'visible')