在Ruby中使用变量的值作为另一个变量名 [英] Using the value of a variable as another variables name in Ruby

问题描述

我刚开始学习Ruby，我编写了一个程序，该程序生成一些数字并将其分配给变量@ one，@ two，@ three等.然后，用户可以通过输入变量来指定要更改的变量名称(例如一个).然后，我需要做类似"@ [valueofinout] = asd"的操作.我将如何执行此操作，是否有更好的方法可以阻止我正在考虑的方法?我找到了

I'm just starting out in learning Ruby and I've written a program that generates some numbers and assigns them to variables @one, @two, @three etc. The user can then specify a variable to change by inputting it's name (e.g one). I then need to do something like '@[valueofinout] = asd'. How would I do this, and is there a better way as the way I'm thinking of seems to be discouraged? I've found

x = "myvar"
myvar = "hi"
eval(x) -> "hi"

但是我不完全理解为什么需要第二行.就我而言，我会使用类似的

but I don't completely understand why the second line is needed. In my case would I use something like

@one = "21"
input = "one"
input = "@" + input
changeto = "22"
eval(input) -> changeto

推荐答案

使用instance_variable_set(

尽管如此，在大多数情况下，您应该将普通的Ruby变量与用户正在与之交互的变量分开.如何创建用户变量哈希，例如

In most cases though, you should separate your normal Ruby variables from the variables your user is interacting with. How about creating a Hash of user variables, e.g.

@uservars = { 'one' => 1, 'two' => 2 }
two = @uservars['two']   # Look up 'two' variable

varname = "myvar"
@uservars[varname] = 5   # Set a variable by name
value = @uservars[varname]  # Get a variable by name 

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