Annotations, Documentation and Comments

The sections below include the coding conventions with respect to annotations, documentation, and comments.

Annotations

• Do not have spaces around the @ symbol.
• Indent annotations to align them with the starting position of the owner (statement or definition).

Example,

// Service annotations are indented to align it with the starting position of the service.
@http:ServiceConfig {
    ...
}
service greetingService on new http:Listener(8080) {
    // Resource annotation is indented to align it with the starting position of the resource.
    @http:ResourceConfig {
      ...
    }
    resource function hello(http:Caller caller, http:Request req) returns error? {
        ...
    }
}

• Each annotation attribute (i.e., key-value pairs) should block indent on its own line..

Example,

@http:ServiceConfig {
    basePath: "greet",
    methods: ["GET"]
}

• If an annotation is empty, place it in a single line and do not have spaces between both braces.

Example,

@http:ServiceConfig {}

• If you are annotating a parameter or a return type, the annotation should be added inline to the parameter or the return type.

Example,

// Parameter annotation.
public function secureFunction1(@sensitive string secureInName, @sensitive int secureInId, string insecureIn) {
    ...
}
  
public function secureFunction2(@sensitive string secureInName,
    @sensitive int secureInId, string insecureIn) {
    ...
}
  
// Return type annotation.
public function taintedReturn1() returns @tainted string {
    ...
}
    
public function taintedReturn2() returns 
    @tainted string {
    ...
}
  

Comments

• Use // for both single-line and multi-line comments.

Example,

// This is a single-line comment.

and

// Copyright (c) 2019 WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
//
// WSO2 Inc. licenses this file to you under the Apache License,
// Version 2.0 (the "License"); you may not use this file except
// in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

• Add a single space between the // and the content.
• If the comment is in its own line, then indent it considering its context (i.e., top-level or in a block).

Example,

// This is a top-level comment.

function func1() {
    // This is a block-level comment. 
}

function func2() {
    if (true) {
        if (true) {
            // This is a nested if block-level comment.
        }
    }
}

• If the comment is in line with the code, add a space before it.

Example,

type People record {}; // Inline comment

function func1() {
    int a = 0; // Inline comment
}

Documentation

• Always, indent them to align with the starting position of the owner.
• Add a space after the # symbol.
• Add an empty line after the description.

Example,

# Description.
#
# + value - value input parameter 
# + return - return a integer value
function getValue(int value) returns int {
    return value;
}

• Add only one space after the parameter marker (+), divider (-), and return.
• Begin the param identifier and description with a single space.

Example,

# Description.
#
# + value - Parameter description
# + return - Return value description
function getValue(int value) returns int {...}

# Description.
@http:ServiceConfig {...}
service greet on new http:Listener(8080) {
    # Description.
    #
    # + caller - Parameter description.
    # + request - Parameter description.
    @http:ResourceConfig {...}
    resource function sayHello(http:Caller caller, http:Request request) {...}
}