Sass 配置compass浏览器支持（compass 1.x语法）

使用Compass的0.12.x版本，我定义了对旧版的支持：

@import "compass/support"

$legacy-support-for-ie6: false;
$legacy-support-for-ie7: true;
$legacy-support-for-ie8: true;
$legacy-support-for-mozilla: false;

@if ($legacy-support-for-ie7) {
  // specific declaration if ie7 is supported
}

我不知道我该如何定义以下内容。 也许是这样的：

// Add support for a specific browser
$browser-minimum-versions: (
  'ie': "7",
  'ie': "8"
);

// Reject browsers
$supported-browsers: reject(browser-versions("ie"), "6", "7", "8");

但它返回该错误（在Compass 1.0.1上运行）：

---

排除浏览器是通过修改

$magnetive usage threshold

变量来完成的。如果浏览器X仅占4.99%的市场份额，则需要将其设置为

5

$debug-browser-support: true;
$browser-minimum-versions: (
  "ie": "9"
);
$graceful-usage-threshold: 4.46163;

@import "compass";

.foo {
  @include opacity(.5);
  @include border-radius(10px);
}

输出：

.foo {
  /* Content for ie 8 omitted.
     Minimum support is 9. */
  opacity: 0.5;
  /* Capability border-radius is not prefixed with -moz because 0.25036% of users are affected which is less than the threshold of 4.46163. */
  /* Capability border-radius is not prefixed with -ms because 0% of users are affected which is less than the threshold of 4.46163. */
  /* Capability border-radius is not prefixed with -o because 0% of users are affected which is less than the threshold of 4.46163. */
  /* Capability border-radius is not prefixed with -webkit because 0.1583% of users are affected which is less than the threshold of 4.46163. */
  border-radius: 10px;
}

.foo {
  /* Content for ie 8 omitted.
     Minimum support is 9. */
  opacity: 0.5;
  /* Capability border-radius is not prefixed with -moz because 0.25036% of users are affected which is less than the threshold of 4.46163. */
  /* Capability border-radius is not prefixed with -ms because 0% of users are affected which is less than the threshold of 4.46163. */
  /* Capability border-radius is not prefixed with -o because 0% of users are affected which is less than the threshold of 4.46163. */
  /* Capability border-radius is prefixed with -webkit because safari "4" is required. */
  /* Creating new -webkit context. */
  -webkit-border-radius: 10px;
  border-radius: 10px;
}

请注意，这会导致排除您可能希望支持的其他少数浏览器。这时，

$browser最低版本就开始起作用了

$browser-minimum-versions: (
  "ie": "9",
  "safari": "4"
);

输出：

.foo {
  /* Content for ie 8 omitted.
     Minimum support is 9. */
  opacity: 0.5;
  /* Capability border-radius is not prefixed with -moz because 0.25036% of users are affected which is less than the threshold of 4.46163. */
  /* Capability border-radius is not prefixed with -ms because 0% of users are affected which is less than the threshold of 4.46163. */
  /* Capability border-radius is not prefixed with -o because 0% of users are affected which is less than the threshold of 4.46163. */
  /* Capability border-radius is not prefixed with -webkit because 0.1583% of users are affected which is less than the threshold of 4.46163. */
  border-radius: 10px;
}

.foo {
  /* Content for ie 8 omitted.
     Minimum support is 9. */
  opacity: 0.5;
  /* Capability border-radius is not prefixed with -moz because 0.25036% of users are affected which is less than the threshold of 4.46163. */
  /* Capability border-radius is not prefixed with -ms because 0% of users are affected which is less than the threshold of 4.46163. */
  /* Capability border-radius is not prefixed with -o because 0% of users are affected which is less than the threshold of 4.46163. */
  /* Capability border-radius is prefixed with -webkit because safari "4" is required. */
  /* Creating new -webkit context. */
  -webkit-border-radius: 10px;
  border-radius: 10px;
}

为了更容易地排除旧浏览器，工作中进行了一些更改。你可以在这里找到它们：

如果要为特定浏览器制定规则，则使用
$critical usage threshold
变量：

$debug-browser-support: true;
$browser-minimum-versions: (
  "ie": "9"
);
$critical-usage-threshold: 4.46163;
$graceful-usage-threshold: 4.46163;

@import "compass";

.foo {
  @include for-legacy-browser('ie', '8') {
    color: green;
    // this is based on $critical-usage-threshold by default
    // if $critical-usage-threshold is lower than the version's usage
    // then this content will be generated
  }
  @if support-legacy-browser('ie', '8') {
    color: red;
  }
}

您想支持哪些浏览器版本？关于IE，>ie7。谢谢。然后，我假设
$generate usage threshold
是一个基于But-Then的百分比，关于我问题的第二部分。如何为特定浏览器添加声明，如
@if（$legacy-support-for-ie7）{//specific declaration}
@raphaellarinaga，已用示例更新。