Homework#4 what is false if I transmit ownership I don't possess

[staufga0]

if I have the following code in Ansem : let x = 2 let y &- x let z <- y

z cannot be properly assigned so it is false, but should I also say that y is misused and false ?

[saucisson]

@kyouko-taiga is it correct in Anzen?

[QuentinRiv]

If I correctly understood how it works, there is no error here.

let x = 2 creates the object 2, makes a reference of x on 2, and x becomes the owner of this object. let y &- x makes a reference between y and the x's object, 2 here (so there is a reference of y on 2) And let z <- y makes a reference of z on 2, as before, and z becomes the new owner of 2, (so not x anymore)

[saucisson]

Yes, here are an example where there is an error.

{
  let x = 2
  let y &- x
  let z <- x
} // here x, y and z are all deleted at the end of the block, so there is no erroneous reference to the value 2

x,y,z are marked as true in the results table.

let x = 2
let y &- x
{
  let z <- x
} // here z is deleted at the end of the block, and thus also deleted the value 2, because it owns it
// x and y both refer to the deleted value 2, and are thus in error

x,y are marked as false in the results table, z is marked as true.

[QuentinRiv]

Moreover, 2 examples : let x = 2 // Creates the object 2, makes a reference of x on 2, whose x is the owner let y = x // Create a new object 2 (different from the previous 2), makes a reference on this new object, and y is the owner of this one

And : let z <- x + 1 // Correct, because x exists, so here, it evaluates x+1, makes a new object of it, and makes a reference of z on this new object, whose z is the owner let w &- x + 1 // Incorrect, because there is no owner of the new object x+1, so this object cannot exist, and so w reference on nothing existing

[staufga0]

so, in the first code : let x = 2 let y &- x let z <- y

z can obtain the ownership of the object refered by x and y but owned by x, even if y doesn't have the ownership of the object it refers to ? x can loose his ownership on the object in the statement : let z <- y ?

[saucisson]

You are right, z cannot get ownership because y does not have ownership.

[staufga0]

so, should I say that y is false, because it's used in a wrong manner, or only z is false ?

[saucisson]

You should say that y is false, and z is false.

[staufga0]

Ok, thank You