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新手问题 ERB 里面 `-%>` 是什么意思啊

blacktulip · August 04, 2013 · Last by luikore replied at August 05, 2013 · 7957 hits

在 github 看到这样的代码

<% if @details.errors.any? -%>
  <div id="error_explanation">
    <ul>
    <% @details.errors.full_messages.each do |msg| %>
      <li><%= msg %></li>
    <% end %>
    </ul>
  </div>
<% end -%>

请问这个 if 和 end 后面的 -%> 是什么意思呢？ 我开始觉得是手误，但是两处都有又不像...

3 likes
luikore #0 August 04, 2013

忽略后面的空格和换行符，使输出更紧凑

3 likes
martin91 #1 August 04, 2013

#1 楼 @luikore 原来是这用法

blacktulip #2 August 04, 2013

#1 楼 @luikore thx，原来是这样

luikore #3 August 04, 2013

另外 <%= expr =%> 相当于 <%= expr -%>

参考 erubis 的文档

~/.rvm/gems/ruby-head/gems/erubis-2.7.0/doc/users-guide.html#topics-trimspaces
blacktulip #5 August 04, 2013

谢谢指点... 幸好没有去发 pr

martin91 #6 August 04, 2013

#4 楼 @luikore 如果是像<%== expr -%>这样的呢，代码来源：https://github.com/citrus/spree_variant_options/blob/master/app/views/spree/products/_variant_options.html.erb 是用于删除前面的空白的吗

luikore #7 August 04, 2013

#7 楼 @Martin91 相当于 <%= raw expr -%>, erb 搞不了前导空白

8 Floor has deleted
martin91 #9 August 04, 2013

#8 楼 @luikore sorry，找到了， http://edgeguides.rubyonrails.org/active_support_core_extensions.html#output-safety

To insert something vzrbatim use the raw helper rather than calling html_safe:

<%= raw @cms.current_template %> <%# inserts @cms.current_template as is %>

or, equivalently, use <%==:

<%== @cms.current_template %> <%# inserts @cms.current_template as is %>
1 likes
Unknow user #10 August 04, 2013

原来如此，又涨姿势了……

huacnlee #11 August 05, 2013

老早就知道这个的作用，但是之前用起来却发现似乎没有效果...

luikore #12 August 05, 2013

#12 楼 @huacnlee erubis 默认支持的 erb 要设置 trim mode

$ erb -T -
<div><%= 1 -%> </div>
^D
<div>1</div>
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