新手问题 ruby 中"变量的变量"如何表示
例如 php 中的以下语法如何表达
1
$var = "name";
$name = "Jobs";
echo ${$var} ; // Jobs
2
class obj{
var $name ;
//
}
$obj = new obj;
$obj->name = "Jobs" ;
$var = "name";
echo $obj->$var ; // Jobs
2
class obj{
var $name ;
//
}
class obj2{
var $var;
//
}
$obj = new obj;
$obj->name = "Jobs" ;
$obj2 = new obj2;
$obj2->var = "name" ;
echo $obj->{$obj2->var} ; // Jobs
第一个可以用 eval 来实现吧：
[4] pry(main)> var = "name"
=> "name"
[5] pry(main)> name = "Jobs"
=> "Jobs"
[6] pry(main)> p eval(var)
"Jobs"
Another :
[8] pry(main)> class Test
[8] pry(main)* attr_accessor :name
[8] pry(main)* end
[12] pry(main)> class Demo
[12] pry(main)* attr_accessor :var
[12] pry(main)* end
test = Test.new
test.name = "Jobs"
demo = Demo.new
demo.var = "name"
[15] pry(main)> test.instance_eval(demo.var)
=> "Jobs"
- 这个貌似只想到了用 eval 方法解决
- 可以用 instance_variable_get 方法来解决
http://apidock.com/ruby/v1_9_3_125/Object/instance_variable_getruby class Fred def initialize(p1, p2) @a, @b = p1, p2 end end fred = Fred.new('cat', 99) fred.instance_variable_get(:@a) #=> "cat" fred.instance_variable_get("@b") #=> 99
这个可以用 method 和 instance_variable_get 来模拟：
module Var
def &(name)
meth = method(name).call
rescue NameError => e
instance_variable_get "@#{name}"
end
end
class Obj
include Var
def initialize
@name = "Jobs"
end
def age
56
end
end
var = "name"
puts Obj.new.&(var)
var = "age"
puts Obj.new.&(var)
