Sass 变量默认作用域 [英] Sass variable default scope

问题描述

我在跨范围使用 Sass 中的变量默认值时遇到问题.我的测试示例是:

I have a problem with using variable defaults in Sass across scopes. My test example is:

@mixin foo { 
        $val: 'red' !default; 
        .bar { 
                color: $val; 
        } 

} 

@include foo; 
.class1 { 
        $val: 'green'; 
        @include foo; 
        .class11 { 
                @include foo; 
        } 
} 

$val: 'black'; 
.class2 { 
        @include foo; 
} 

.class3 { 
        $val: 'blue'; 
        @include foo; 
} 

.class4 { 
        @include foo; 

}

编译为:

.bar { 
  color: "red"; 

} 

.class1 .bar { 
  color: "red"; 
} 

.class1 .class11 .bar { 
  color: "red"; 
} 

.class2 .bar { 
  color: "black"; 
} 

.class3 .bar { 
  color: "blue"; 
} 

.class4 .bar { 
  color: "blue"; 

}

如你所见，变量 $val 在 mixin foo 中被定义为 'red' !default.我希望导入 mixin 会将 $val 设置为 'red' ，除非它已经定义.但是，在 class1 中，$val 在本地定义为green"，导入 mixin foo 会用red"覆盖它.在其他类中，在 $val 全局定义为 'black' 之后，导入 mixin 会按预期工作，并且 $val 保留其已定义的值.

As you can see, variable $val is defined as 'red' !default in the mixin foo. I expect that importing the mixin would set $val to 'red' unless it is already defined. However, in class1, where $val is locally defined as 'green', importing the mixin foo overwrites it with 'red'. In other classes, after the global definition of $val as 'black', importing the mixin works as expected and $val retains its already defined value.

我做错了什么?

推荐答案

在 class1 本地定义 $val: 'green' 不会改变 $val: 'red' !defaultcode> 在 mixin 中，因为它寻找全局 $val.此时，还没有定义全局 $val.

Defining $val: 'green' locally in class1 does not alter $val: 'red' !default in mixin, because it look for global $val. At this point, no global $val has been defined.

然后全局 $val 被定义为 'black'.在 mixin 中的 $val 之后查找全局 $val.至此，全局$val已经被定义为'black'.

Then global $val is defined as 'black'. After this $val in mixin look for global $val. At this point, global $val has been defined as 'black'.

在本地再次定义 $val 将改变已定义的全局 $val.

Defining $val again locally will alter global $val that has been defined.

@mixin foo 
  $val: 'red' !default // defined locally
  .bar
    color: $val

@include foo // $val in mixin foo look for global $val. no global $val found, then 'red'

.class1
  $val: 'green'
  @include foo // $val in mixin foo look for global $val. no global $val found, then 'red'
  color: $val // local $val 'green'
  .class11 
    @include foo // $val in mixin foo look for global $val. no global $val found, then 'red'

$val: 'black' // defined globally at the first time

.class2 
  @include foo // $val in mixin foo look for global $val. $val found, 'black'

.class3
  $val: 'blue' // change the gobal $val
  @include foo // $val in mixin foo look for global $val. $val found, 'blue'

.class4
  @include foo // $val in mixin foo look for global $val. $val found, 'blue'

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