การกำหนด struct

When values belong together, like a point's x and y, you can bundle them into one custom type. In Mojo that bundle is a struct. 📦

You define a new type with the struct keyword, a name, and a colon. Everything indented under it belongs to that type.

Struct names use CapitalizedNames by convention, so Point or BankAccount. This makes your types easy to spot in code.

Inside a struct you list its fields, the named pieces of data it stores. Each field is declared with var and a type.

Mojo structs are static, so each field must state its type up front. That lets the compiler lay out memory efficiently.

A struct definition is just a blueprint. It describes the shape of data but does not create any actual value on its own yet.

From one blueprint you make many instances, each with its own values. The struct is the mold; instances are what comes out of it.

Without a struct you juggle separate x and y variables everywhere. A struct keeps related data together, so it travels as one unit.

In Mojo a struct is a value type. Assigning it copies the data, which keeps behavior predictable and fast by default.

Here is a full struct with two fields. This single definition now describes every Point your program will ever create.

Read a struct as: here is a new type, and here is the data it carries. That mental model carries you through the whole course.

Let us check your grasp of defining a struct.

You met the struct: a blueprint that bundles typed fields into one value type. Next you will fill it with real data using __init__. 🎉