Generated code

Generated code

ScalaBuff generates a single top-level, outer object for each proto file that has the same name (only CamelCased) as that proto file itself by default; this can be overriden by the top-level scala_outer_classname option, like so:

option scala_outer_classname = "MyClass";

Additionally, for compatibility with Java, the java_outer_classname option is supported as well.

The generated outer object will be placed in package that was declared in the input proto file. If the scala_package top-level option is used, then the object will be placed in that package instead:

option scala_package = "com.author.project";

Additionally, for compatibility with Java, the java_package option is supported as well.

Messages

For each Message found in the input proto file, a final, immutable case class and a companion object are generated; the case class has a constructor allowing users to set all available fields at construction time, however all fields are optional. Unlike the Java generated classes, required fields are always counted as set and required fields are initialized to their default values if not initialized by the user in the constructor. This means that the Message is always initialized and ready to be serialized state. Optional fields must be wrapped in an Option, and repeated fields must be Vectors of the appropriate type.

The generated messages can be optimized either for speed (default) or small code size, by setting the optimize_for top-level option:

option optimize_for = SPEED; // default
option optimize_for = CODE_SIZE;

If optimizing for code size, methods may require more time and/or memory to complete, but the generated classes will be smaller.

Since Message classes are immutable, each "mutator" operation returns a new Message instance. Therefore, it is more efficient to set all needed fields in the constructor than call setter methods.

A default instance of each message is provided, accessed by either defaultInstance or getDefaultInstance. It has all fields set to their default values, and is identical to simply constructing a new message with no fields set.

Fields

Each field contained in the input proto file is a val in the generated case class, which means it is immutable and can be accessed by simply using it as a normal class field. Additionally, each optional field has a corresponding getOptionalField method, which returns the field itself instead of the field wrapped in Option.

Field names are CamelCased, so my_field in the proto file becomes myField. In addition, each field has its own field number integer constant in the companion object, which is upper cased.

Fields cannot be mutated directly, so mutator methods are defined for each field, each of which returns a new instance which is identical in every way, except for the mutated field.

Required and optional fields

Each of these types of fields receives its own setField method, that returns a new copy of the current Message with only that field set. For optional fields, unlike in the constructor, it's not needed (or possible) to wrap the value in a Some - that is done automatically by the setter method.

If trying to access a required field that has not been manually initialized (whether in the constructor or via a setter mutator), the default value for that field is returned. Unitialized optional fields have None as their value, so if you want their default value, call getOptionalField instead of accessing them directly.

Additionally, it's possible to clear a required or optional field to its default value by calling clearField; it will return a new instance with the specified field reset to its default value. Note that the message is still fully initialized even if a field is cleared.

Repeated Fields

Each repeated field has a number of methods:

• setField(index, value): Returns a new instance that has the repeated field mutated so that the specified index is set to value.
• addField(value): Returns a new instance that has the repeated field mutated so that value is added.
• addAllField(value1, value2, ...): Returns a new instance that has the repeated field mutated so that all the specified values are added.
• addAllField(collection): Returns a new instance that has the repeated field mutated so that all the values in the specified collection are added; collection must be a subtype of TraversableOnce.

Enumerations

Enumerations are supported by ScalaBuff.

Extensions

ScalaBuff currently doesn't support extensions.

Services

ScalaBuff currently doesn't support extensions.