Structures
Structures are away of composing data so multiple bits of information can be parsed together rather than individually.
To define a new type of structure you need to use the struct keyword in the top level of a file, then define the attributes similar to how variable names are reserved.
struct Person {
name: String,
height: float,
age: int
}
You can then create a instance of a structure in a very similar manner
let geff = Person {
name: "Geff",
height: 178,
age: 27
};
When accessing the values of a structure it is decomposed, meaning each attribute is now treated like a variable. And thus like a standard variable they can return back to the undefined state.
printNameTag(geff.name); // (1)
- Geff's name has been consumed by the function, and thus they now have an undefined name attribute.
The only issue with leaving a structure's attribute undefined is when the value is dropped or when you attempt to use the whole structure. Continuing from the previous example if we attempted to run the code.
employ(geff); // error: geff.name undefined
We will get a compile error as Geff does not have a name property.
Similarly if the function returns, or the variable falls out of scope (the code travels up a block from when it was defined) - if this structure has the drop trait implemented. You will get a compile error, as the compiler cannot call drop on your variable as it has an undefined attribute.