ruby - 迭代器内的 Ruby instance_variable_set 错误：“market_0_home”不允许作为实例变量名

Question

首先，这是@market_0_home 在下面迭代之外的分配，只是为了向您展示我尝试过

>> @market_0_home = 3
=> 3

好的，那里没有错误，现在让我们在一个有点复杂的迭代中尝试一下

>> markets
=> [{"home"=>"CO", "name"=>"David Douglas"}, {"home"=>"SC", "name"=>"David Robertson"}]
>> markets.each_with_index do |market, i|
?> market.each do |name, v|
?> instance_variable_set "market_#{i}_#{name}", v
>> end
>> end
NameError: `market_0_home' is not allowed as an instance variable name
from (irb):23:in `instance_variable_set'
from (irb):23
from (irb):22:in `each'
from (irb):22
from (irb):25:in `each_with_index'
from (irb):21:in `each'
from (irb):21:in `each_with_index'
from (irb):21
>> 

Answer 1

我@在下面的行中添加了一个变量名instance_variable_set：

@market_0_home = 3
markets = [{"home"=>"CO", "name"=>"David Douglas"}, {"home"=>"SC", "name"=>"David Robertson"}]
markets.each_with_index do |market, i|
  market.each do |name, v|
    instance_variable_set "@market_#{i}_#{name}", v
  end
end

当我运行它时，它工作正常。

=> 3
>> markets = [{"home"=>"CO", "name"=>"David Douglas"}, {"home"=>"SC", "name"=>"David Robertson"}]
=> [{"home"=>"CO", "name"=>"David Douglas"}, {"home"=>"SC", "name"=>"David Robertson"}]
>> markets.each_with_index do |market, i|
?>       market.each do |name, v|
?>           instance_variable_set "@market_#{i}_#{name}", v
>>       end
>>   end
=> [{"home"=>"CO", "name"=>"David Douglas"}, {"home"=>"SC", "name"=>"David Robertson"}]
>> @market_0_home
=> "CO"
>> @market_1_home
=> "SC"