如何将字符串转换为Ruby中的变量的引用? [英] How do I convert a string into a reference to a variable in Ruby?
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问题描述
我需要能够将一个变量的名称传递给一个表达式(在黄瓜中),并且希望能够将该字符串转换为一个引用(即不是副本)变量。
I need to be able to pass the name of a variable into an expression (in cucumber) and would like to be able to convert that string into a reference (i.e. not a copy) of the variable.
例如
Given /^I have set an initial value to @my_var$/ do
@my_var = 10
end
# and now I want to change the value of that variable in a different step
Then /^I update "([^"]*)"$/ do |var_name_string|
# I know I can get the value of @my_var by doing:
eval "@my_var_copy = @#{var_name_string}"
# But then once I update @my_var_copy I have to finish by updating the original
eval "@#{var_name_string} = @my_var_copy"
# How do instead I create a reference to the @my_var object?
end
一个反射语言我敢肯定我想要做的是可能的,但我还没有破解它。
Since Ruby is such a reflective language I'm sure what I'm trying to do is possible but I haven't yet cracked it.
推荐答案
class Reference
def initialize(var_name, vars)
@getter = eval "lambda { #{var_name} }", vars
@setter = eval "lambda { |v| #{var_name} = v }", vars
end
def value
@getter.call
end
def value=(new_value)
@setter.call(new_value)
end
end
从 http://onestepback.org/index.cgi/Tech/Ruby/RubyBindings.rdoc 。祝你好运!
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