将字符串文字转换为变量名

Question

I want to create an instance of a class with the name of a string. For example:

sub_string = "tropical"
string = "forest.#{sub_string}"

My class Instance should be foresttropical = Class_name.new or forest_tropical = Class_name.new .

I want to create a class instance with the variable name foresttropical or foresttropical . Is there any way to do it?

I am using:

constantized_var = "forestarea#{x}".capitalize.constantize
constantized_var = Class_name.new

In Plane, I want it to be like this:

x = "tropical"
"forestarea#{x}" = ClassName.new equals forestareatropical = ClassName.new
x = "subtropical"
"forestarea#{x}" = ClassName.new

But it is giving me an error:

uninitialized constant Forestareatropical

Answer 1

If your class name is ForestTropical then you can do like this to create new class instance.

s1 = "forest"
s2 = "tropical"
new_instance = "#{s1}_#{s2}".classify.constantize.new
# new_instance will be the new instance of your class ForestTropical

I hope this helps.

Edit

As per your requirements it ll be something like this

x = "tropical"
instance_variable_set("@forestarea#{x}",ClassName.new)
x = "subtropical"
instance_variable_set("@forestarea#{x}",ClassName.new)

Answer 2

I would avoid forest.tropical as a name for your object, because in Ruby syntax that looks like you are calling a method called tropical on an instance called forest which I don't think is what you want here. So, stick with forest_tropical as your instance name.

You might try using instance_variable_set here:

sub_string = "tropical"
string = "forest_#{sub_string}"
instance_variable_set('@'+string, ClassName.new)

Now you have @forest_tropical which is an instance of the ClassName class.

Or, according to your edit, you can do:

x = "tropical"
instance_variable_set("@forestarea#{x}", ClassName.new)
x = "subtropical"
instance_variable_set("@forestarea#{x}", ClassName.new)

Now you have two instance variables, @forestareatropical and @forestareasubtropical both of the ClassName class.

Answer 3

maybe you should consider using hashes with appropriate keys instead. Since your instance variable names are dynamic anyway, I assume that they will be used in a dynamic context, and for this hashes are better suited.