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codingconventions.qdoc
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codingconventions.qdoc
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/****************************************************************************
**
** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: Nokia Corporation (qt-info@nokia.com)
**
** This file is part of the documentation of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:FDL$
** No Commercial Usage
** This file contains pre-release code and may not be distributed.
** You may use this file in accordance with the terms and conditions
** contained in the Technology Preview License Agreement accompanying
** this package.
**
** GNU Free Documentation License
** Alternatively, this file may be used under the terms of the GNU Free
** Documentation License version 1.3 as published by the Free Software
** Foundation and appearing in the file included in the packaging of this
** file.
**
** If you have questions regarding the use of this file, please contact
** Nokia at qt-info@nokia.com.
** $QT_END_LICENSE$
**
****************************************************************************/
/*!
\page qml-coding-conventions.html
\title QML Coding Conventions
This document contains the QML coding conventions that we follow in our documentation and examples and recommend that others follow.
This page assumes that you are already familiar with the QML language.
If you need an introduction to the language, please read \l {Introduction to the QML language}{the QML introduction} first.
\section1 QML Objects
Through our documentation and examples, QML objects are always structured in the following order:
\list
\o id
\o property declarations
\o signal declarations
\o JavaScript functions
\o object properties
\o child objects
\o states
\o transitions
\endlist
For better readability, we separate these different parts with an empty line.
For example, a hypothetical \e photo QML object would look like this:
\snippet doc/src/snippets/declarative/codingconventions/photo.qml 0
\section1 Grouped Properties
If using multiple properties from a group of properties,
we use the \e {group notation} rather than the \e {dot notation} to improve readability.
For example, this:
\snippet doc/src/snippets/declarative/codingconventions/dotproperties.qml 0
can be written like this:
\snippet doc/src/snippets/declarative/codingconventions/dotproperties.qml 1
\section1 Private Properties
QML and JavaScript do not enforce private properties like C++. There is a need
to hide these private properties, for example, when the properties are part of
the implementation. As a convention, private properties begin with two
\e underscore characters. For example, \c __area, is a property that is
accessible but is not meant for public use. Note that QML and JavaScript will
grant the user access to these properties.
\snippet doc/src/snippets/declarative/codingconventions/private.qml 0
\section1 Lists
If a list contains only one element, we generally omit the square brackets.
For example, it is very common for a component to only have one state.
In this case, instead of:
\snippet doc/src/snippets/declarative/codingconventions/lists.qml 0
we will write this:
\snippet doc/src/snippets/declarative/codingconventions/lists.qml 1
\section1 JavaScript Code
If the script is a single expression, we recommend writing it inline:
\snippet doc/src/snippets/declarative/codingconventions/javascript.qml 0
If the script is only a couple of lines long, we generally use a block:
\snippet doc/src/snippets/declarative/codingconventions/javascript.qml 1
If the script is more than a couple of lines long or can be used by different objects, we recommend creating a function and calling it like this:
\snippet doc/src/snippets/declarative/codingconventions/javascript.qml 2
For long scripts, we will put the functions in their own JavaScript file and import it like this:
\snippet doc/src/snippets/declarative/codingconventions/javascript-imports.qml 0
*/