动态命名实例变量 Ruby

Question

我想做的是动态命名变量，例如：

def instance(instance)
    @instance = instance #@instance isn't actually a variable called @instance, rather a variable called @whatever was passed as an argument
end

我该怎么做？

Answer 1

使用instance_variable_set。

varname = '@foo'
value = 'bar'
self.instance_variable_set varname, value
@foo   # => "bar"

或者，如果您不希望调用者必须提供“@”：

varname = 'foo'
value = 'bar'
self.instance_variable_set "@#{varname}", value
@foo   # => "bar"

Answer 2

如果我理解正确，您想使用“instance_variable_set”：

class A
end

a = A.new
a.instance_variable_set("@whatever", "foo")

a.instance_variable_get("@whatever") #=> "foo"

Answer 3

你真的不能。

您可以使用eval，但实际上它不可读。

使用正确的if 或改用哈希。

# With Hash:
values = {}
a = :foo
values[a] = "bar"
values[:foo] # => "bar"

# With if
calc = "bar"
if a_is_foo
  foo = calc
else
  oof = calc
end
foo # => "bar"