Why would str2=str create a new string?
How are RStrings modified when they are referenced by other shared RStrings?
Is there any way to create a shared RString other than calling .dup?
How are RStrings modified when they are referenced by other shared RStrings?
Is there any way to create a shared RString other than calling .dup?
But for today:
1. str2 = str doesn't actually create a new string. RString represents a string value, not a string object. So str2=str creates a new RString because that essentially defines what str2's value refers to… Think of RString as an internal pointer to the value that str or str2 is referring to. Sorry - not a good explanation :(
2. How are shared RStrings modified? Not sure yet, but I'm curious to find out. Will let you know on my site somehow.
3. Yes, simply calling str2 = str or in a variety of other ways will do it.
str = "foo"
str2 = str
str.object_id == str2.object_id #=> true
I am not sure about 2) and 3) but I'd expect some copy-on-write mechanism based on a flag field in the RBasic struct, and taking substrings might be O(1) thanks to sharing too.
In Ruby, most classes (including String) are reference types. This is why `str2 = str` doesn't create a new string. It doesn't create a new RString either - str and str2 are both pointers to the same RString struct.
I think to actually see shared strings behavior, you would have to do str2 = str.clone or str2 = str[0..-1].