{…}什么意思？
{…}什么意思？
提问于 2013-08-06 20:37:17
如“为什么是痛苦指南”中的以下代码：
def wipe_mutterings_from( sentence )
unless sentence.respond_to? :include?
raise ArgumentError, "cannot wipe mutterings from a #{ sentence.class }"
end
while sentence.include? '('
open = sentence.index( '(' )
close = sentence.index( ')', open )
sentence[open..close] = '' if close
end
end回答 3
Stack Overflow用户
回答已采纳
发布于 2013-08-06 20:42:05
在Ruby双引号字符串(包括s = "…"和s = %Q{ ... }等字符串文字)和s = <<ENDCODE-the语法中，#{ … }用于“字符串内插”，将动态内容插入到字符串中。例如：
i = 42
s = "I have #{ i } cats!"
#=> "I have 42 cats!"它与使用字符串连接以及显式调用相比(但比使用更方便的to_s和更有效)等效。
i = 42
s= "I have " + i.to_s + " cats!"
#=> "I have 42 cats!"您可以在区域内放置任意代码，包括多行上的多个表达式。评估代码的最终结果是to_s调用它以确保它是一个字符串值：
"I've seen #{
i = 10
5.times{ i+=1 }
i*2
} weasels in my life"
#=> "I've seen 30 weasels in my life"
[4,3,2,1,"no"].each do |legs|
puts "The frog has #{legs} leg#{:s if legs!=1}"
end
#=> The frog has 4 legs
#=> The frog has 3 legs
#=> The frog has 2 legs
#=> The frog has 1 leg
#=> The frog has no legs请注意，这在单引号字符串中没有任何影响：
s = "The answer is #{6*7}" #=> "The answer is 42"
s = 'The answer is #{6*7}' #=> "The answer is #{6*7}"
s = %Q[The answer is #{ 6*7 }] #=> "The answer is 42"
s = %q[The answer is #{ 6*7 }] #=> "The answer is #{6*7}"
s = <<ENDSTRING
The answer is #{6*7}
ENDSTRING
#=> "The answer is 42\n"
s = <<'ENDSTRING'
The answer is #{6*7}
ENDSTRING
#=> "The answer is #{6*7}\n"为了方便起见，如果只想插入实例变量(@foo)、全局变量($foo)或类变量(@@foo)的值，用于字符串内插的@foo字符是可选的：
@cats = 17
s1 = "There are #{@cats} cats" #=> "There are 17 cats"
s2 = "There are #@cats cats" #=> "There are 17 cats"Stack Overflow用户
发布于 2013-08-06 20:38:22
"#{}"的意思是在Ruby interpolation.See Here中有太多答案。
Stack Overflow用户
发布于 2013-08-06 20:40:54
#{}用于红宝石插值。在这个例子中，
这将引发带有消息的ArgumentError，
cannot wipe mutterings from a <whatever sentence.class evaluates to>
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原文链接：
https://stackoverflow.com/questions/18089993
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