From 971292128b292052ef935da67a5d04fb5a3753f4 Mon Sep 17 00:00:00 2001 From: Mitch Curtis Date: Wed, 14 Mar 2018 15:46:28 +0100 Subject: Doc: improve "Separate UI from Logic" section Change-Id: I0d36e009b4551e45e5e7fda6c95fc3fbfabfe1a5 Reviewed-by: Simon Hausmann --- .../doc/src/guidelines/qtquick-bestpractices.qdoc | 48 ++++++++++++++-------- 1 file changed, 31 insertions(+), 17 deletions(-) (limited to 'src/quick/doc/src') diff --git a/src/quick/doc/src/guidelines/qtquick-bestpractices.qdoc b/src/quick/doc/src/guidelines/qtquick-bestpractices.qdoc index 20ea8ec48c..9d411a581f 100644 --- a/src/quick/doc/src/guidelines/qtquick-bestpractices.qdoc +++ b/src/quick/doc/src/guidelines/qtquick-bestpractices.qdoc @@ -126,33 +126,47 @@ in your project's build directory and rename it to, for example, \li \l{The Qt Resource System} \endlist -\section1 Application UI and Business Logic +\section1 Separate UI from Logic One of the key goals that most application developers want to achieve is to create a maintainable application. One of the ways to achieve this goal is -to separate the UI from the business logic. The following are a few reasons -why application's UI should be in QML: +to separate the user interface from the business logic. The following are a few +reasons why an application's UI should be written in QML: \list - \li QML is a declarative language, which suits best for defining UIs. - \li It's easier to embed JavaScript in QML to respond to events, for example. - \li QML is faster to code as it is not strongly typed. + \li Declarative languages are strongly suited for defining UIs. + \li QML code is simpler to write, as it is less verbose than C++, and is not + strongly typed. This also results in it being an excellent language to + prototype in, a quality that is vital when collaborating with designers, + for example. + \li JavaScript can easily be used in QML to respond to events. \endlist -On the other hand, C++ being a strongly typed language, suits best for defining -business logic. Typically, such code performs tasks such as complex calculations -or larger data processing, which can be faster with C++ than with QML. +Being a strongly typed language, C++ is best suited for an application's logic. +Typically, such code performs tasks such as complex calculations +or data processing, which are faster in C++ than QML. Qt offers various approaches to integrate QML and C++ code in an application. -In most cases, the C++ part (business logic) provides the data model to the QML -part (UI), which presents it in a readable form. It is often a challenge to -decide when to use this approach. It is recommended to use QML -if the data model is static, simple, and small, as C++ could be overkill. -Use C++ if the application depends on a dynamic, large, and complex data model. +A typical use case is displaying a list of data in a user interface. +If the data set is static, simple, and/or small, a model written in QML can be +sufficient. -\omit -examples snippets of simpler and complex data models. -\endomit +The following snippet demonstrates examples of models written in QML: + +\qml + model: ListModel { + ListElement { name: "Item 1" } + ListElement { name: "Item 2" } + ListElement { name: "Item 3" } + } + + model: [ "Item 1", "Item 2", "Item 3" ] + + model: 10 +\endqml + +Use \l {QAbstractItemModel Subclass}{C++} for dynamic data sets that are large +or frequently modified. \section2 Interaction Path -- cgit v1.2.3