Assertion Casting ​

Assertion casting is a method supported for all dynamic types. In Jule runtime, casting a dynamic type to an incorrect type results in a panic. To prevent this, methods such as the type match statement can be used. However, assertion casting provides a more elegant and simpler way to achieve this. It is often a better choice than solutions like type match, especially when only a small number of types need to be handled.

Assertion casting means that a casting expression returns two values. One of these values is the actual value held by the dynamic type if the casting is successful, while the other is a boolean indicating whether the casting was successful or not.

For example:

x := any("hello world")
s, ok := any(x)
println(s)
println(ok)

In the code above, an assertion casting has been applied. The variable s is assigned the value inside the dynamic type if the casting is successful; otherwise, it is assigned the default value of the type. The variable ok is equal to true if the casting is successful and false if it fails.