Reference

References will take the place of pointers. When finished, the pointers documentation will be removed.

A reference is a .NET garbage collected pointer to an object instance.

In .NET the the type determines the kind of reference. Regular classes are reference-types and structs are value-types.

Type	Description
Reference	The object instance is passed by reference.
Value	The object instance is passed by value (copied).

A reference type can never be passed by value (without explicitly copying). A value type can be passed by reference (ref keyword in C#).

---

Z#	C#	Description
struct	record	Reference Type with value semantics
custom data type	struct	A value object

ref         # keyword
Ref<T>      # Wrapper Type
.Ref()      # Conversion Function

Use Ref<T> type to indicate the type is a reference type or the function parameter is by-ref or the variable is a reference (explicit).

// reference type
MyRefType: Ref              // no <T>
MyRefType: Reference        // alternate
    ...
MyDerivedRefType: Ref<U8>   // make an explicit ref-type based on a value-type

fn: (p: Ref<U8>)
    p = 42          // changes value on call site


a := 42
r: Ref<U8> = a.Ref()    // convert 'a' to a Ref (explicit var)
r := a.Ref()            // convert 'a' to a Ref (implicit var)
r: Ref<U8> = 42         // Error! cannot take ref from a literal

---

TBD

Copy-on-write

• Find a way to limit a reference’s reach. When passing the same thing to multiple places, control (let it be controlled by the receiver?) who sees these changes? Make a copy at some point - with all the problems that come with making copies…

In certain situation dotent makes defensive copies of structs…

a :=^ 42    // mutable
r := a.CopyOnWriteRef()
a = 101
// a = 101
// r = 42

---

match all C# struct ref scenarios

• in / out / ref
• readonly
• ref return
• scoped keyword
• readonly ref readonly int constant