pass by reference but reference to data and not to variable

Question

This is psesudo code. In what programming language this is possible ?

def lab(input)
  input = ['90']
end

x = ['80']
lab(x)

puts x #=> value of x has changed from ['80'] to ['90]

I have written this in ruby but in ruby I get the final x value of 80 because ruby is pass-by-reference. However what is passed is the reference to the data held by x and not pointer to x itself same is true in JavaScript. So I am wondering if there is any programming language where the following is true.

Answer 1

There are several languages that support pass-by-reference: it was implicit in most Fortran versions for longer than most other programming languages have existed (some versions used copies back and forth, but the end result had better be the same;-), it was specified by var in Pascal in the '70s (though the default, if you didn't say var, was by copy), etc, etc.

Most modern languages (Java, Python, Ruby, Javascript, Go, ...) uniformly pass (and assign) by object-reference (which is what you call "reference to data"), though some are more complex and let you specify more precisely what you want (e.g., C++, C#).

Answer 2

So in Ruby, you can't make x reference another object from within a method, but you can change the object itself, in your case what you want can be achieved using mutating methods (Array#replace could be handy in case of arrays, for example):

def lab input
  input.replace ['90']
end

x = ['80']
#=> ["80"]
lab x
#=> ["90"]
x
#=> ["90"]