The Ring programming language version 1.4.1 book - Part 19 of 31

Ring Documentation, Release 1.4.1
Note: the functions pDebug(), pRun() and pRunNoConsole() in the previous sample are not portable! They are
written in this sample for MS-Windows and we can update them for other operating systems.
52.54 The Cards Game
In the next example we will see a simple Cards game developed using RingQt
Each player get 5 cards, the cards are unknown to any one. each time one player click on one card to see it. if the card
is identical to another card the play get point for each card. if the card value is “5” the player get points for all visible
cards.
Load "guilib.ring"
nScale = 1
app1 = new qApp
mypic = new QPixmap("cards.jpg")
mypic2 = mypic.copy(0,(124*4)+1,79,124)
Player1EatPic = mypic.copy(80,(124*4)+1,79,124)
Player2EatPic= mypic.copy(160,(124*4)+1,79,124)
aMyCards = []
aMyValues = []
for x1 = 0 to 3
for y1 = 0 to 12
temppic = mypic.copy((79*y1)+1,(124*x1)+1,79,124)
aMyCards + temppic
aMyValues + (y1+1)
next
next
52.54. The Cards Game 518

nPlayer1Score = 0 nPlayer2Score=0
do
Page1 = new Game
Page1.Start()
again Page1.lnewgame
mypic.delete()
mypic2.delete()
Player1EatPic.delete()
Player2EatPic.delete()
for t in aMyCards
t.delete()
next
func gui_setbtnpixmap pBtn,pPixmap
pBtn {
setIcon(new qicon(pPixmap.scaled(width(),height(),0,0)))
setIconSize(new QSize(width(),height()))
}
Class Game
nCardsCount = 10
win1 layout1 label1 label2 layout2 layout3 aBtns aBtns2
aCards nRole=1 aStatus = list(nCardsCount) aStatus2 = aStatus
aValues aStatusValues = aStatus aStatusValues2 = aStatus
Player1EatPic Player2EatPic
lnewgame = false
nDelayEat = 0.5
nDelayNewGame = 1
func start
win1 = new qWidget() {
setwindowtitle("Five")
setstylesheet("background-color: White")
showfullscreen()
}
layout1 = new qvboxlayout()
label1 = new qlabel(win1) {
settext("Player (1) - Score : " + nPlayer1Score)
setalignment(Qt_AlignHCenter | Qt_AlignVCenter)
setstylesheet("color: White; background-color: Purple;
font-size:20pt")
setfixedheight(200)
}
closebtn = new qpushbutton(win1) {
settext("Close Application")
setstylesheet("font-size: 18px ; color : white ;
background-color: black ;")
setclickevent("Page1.win1.close()")
}

aCards = aMyCards
aValues = aMyValues
layout2 = new qhboxlayout()
aBtns = []
for x = 1 to nCardsCount
aBtns + new qpushbutton(win1)
aBtns[x].setfixedwidth(79*nScale)
aBtns[x].setfixedheight(124*nScale)
gui_setbtnpixmap(aBtns[x],mypic2)
layout2.addwidget(aBtns[x])
aBtns[x].setclickevent("Page1.Player1click("+x+")")
next
layout1.addwidget(label1)
layout1.addlayout(layout2)
label2 = new qlabel(win1) {
settext("Player (2) - Score : " + nPlayer2Score)
setalignment(Qt_AlignHCenter | Qt_AlignVCenter)
setstylesheet("color: white; background-color: red;
font-size:20pt")
setfixedheight(200)
}
layout3 = new qhboxlayout()
aBtns2 = []
aBtns2 + new qpushbutton(win1)
aBtns2[x].setfixedwidth(79*nScale)
aBtns2[x].setfixedheight(124*nScale)
gui_setbtnpixmap(aBtns2[x],mypic2)
layout3.addwidget(aBtns2[x])
aBtns2[x].setclickevent("Page1.Player2click("+x+")")
next
layout1.addwidget(label2)
layout1.addlayout(layout3)
layout1.addwidget(closebtn)
win1.setlayout(layout1)
app1.exec()
Func Player1Click x
if nRole = 1 and aStatus[x] = 0
nPos = ((random(100)+clock())%(len(aCards)-1)) + 1
gui_setbtnpixmap(aBtns[x],aCards[nPos])
del(aCards,nPos)
nRole = 2
aStatus[x] = 1
aStatusValues[x] = aValues[nPos]
del(aValues,nPos)
Player1Eat(x,aStatusValues[x])
checknewgame()

ok
Func Player2Click x
if nRole = 2 and aStatus2[x] = 0
nPos = ((random(100)+clock())%(len(aCards)-1)) + 1
gui_setbtnpixmap(aBtns2[x],aCards[nPos])
del(aCards,nPos)
nRole = 1
aStatus2[x] = 1
aStatusValues2[x] = aValues[nPos]
del(aValues,nPos)
Player2Eat(x,aStatusValues2[x])
checknewgame()
ok
Func Player1Eat nPos,nValue
app1.processEvents()
delay(nDelayEat)
lEat = false
if aStatus2[x] = 1 and (aStatusValues2[x] = nValue or nValue=5)
aStatus2[x] = 2
gui_setbtnpixmap(aBtns2[x],Player1EatPic)
lEat = True
nPlayer1Score++
ok
if (x != nPos) and (aStatus[x] = 1) and
(aStatusValues[x] = nValue or nValue=5)
aStatus[x] = 2
gui_setbtnpixmap(aBtns[x],Player1EatPic)
lEat = True
nPlayer1Score++
ok
next
if lEat
nPlayer1Score++
gui_setbtnpixmap(aBtns[nPos],Player1EatPic)
aStatus[nPos] = 2
label1.settext("Player (1) - Score : " + nPlayer1Score)
ok
Func Player2Eat nPos,nValue
delay(nDelayEat)
lEat = false
if aStatus[x] = 1 and (aStatusValues[x] = nValue or nValue = 5)
aStatus[x] = 2
gui_setbtnpixmap(aBtns[x],Player2EatPic)
lEat = True
nPlayer2Score++
ok
if (x != nPos) and (aStatus2[x] = 1) and

(aStatusValues2[x] = nValue or nValue=5 )
aStatus2[x] = 2
gui_setbtnpixmap(aBtns2[x],Player2EatPic)
lEat = True
nPlayer2Score++
ok
next
if lEat
nPlayer2Score++
gui_setbtnpixmap(aBtns2[nPos],Player2EatPic)
aStatus2[nPos] = 2
label2.settext("Player (2) - Score : " + nPlayer2Score)
ok
Func checknewgame
if isnewgame()
lnewgame = true
if nPlayer1Score > nPlayer2Score
label1.settext("Player (1) Wins!!!")
ok
if nPlayer2Score > nPlayer1Score
label2.settext("Player (2) Wins!!!")
ok
delay(nDelayNewGame)
win1.delete()
app1.quit()
ok
Func isnewgame
for t in aStatus
if t = 0
return false
ok
next
for t in aStatus2
if t = 0
return false
ok
next
return true
Func delay x
nTime = x * 1000
oTest = new qTest
oTest.qsleep(nTime)
The application during the runtime

Note: in the previous screen shot the player get the card number ‘5’ but his score is not increased because he opened
this card while no other cards are visible!
The next screen shot while running the game using a Mobile (Android)

Note: using Qt we can run the same application on other Mobile systems
52.55 Classes and their Methods to use the default events
The next table present the class name and the methods that we have to use the default events.
Class Name Methods to use the default Events
QPushButton SetClickEvent()
QAction SetClickEvent()
QLineEdit SetTextChangedEvent()
SetCursorPositionChangedEvent()
SetEditingFinishedEvent()
SetReturnPressedEvent()
SetSelectionChangedEvent()
SetTextEditedEvent()
QTextEdit SetCopyAvailableEvent()
SetCurrentCharFormatChangedEvent()
SetCursorPositionChangedEvent()
SetRedoAvailableEvent()
Continued on next page
52.55. Classes and their Methods to use the default events 524

Table 52.1 – continued from previous page
SetTextChangedEvent()
SetUndoAvailableEvent()
QListWidget SetCurrentItemChangedEvent()
SetCurrentRowChangedEvent()
SetCurrentTextChangedEvent()
SetItemActivatedEvent()
SetItemChangedEvent()
SetItemClickedEvent()
SetItemDoubleClickedEvent()
SetItemEnteredEvent()
SetItemPressedEvent()
SetItemSelectionChangedEvent()
QTreeView SetCollapseEvent()
SetExpandedEvent()
SetActivatedEvent()
SetClickedEvent()
SetDoubleClickedEvent()
SetEnteredEvent()
SetPressedEvent()
SetViewportEnteredEvent()
QTreeWidget SetCollapsedEvent()
SetExpandedEvent()
SetActivatedEvent()
SetClickedEvent()
SetDoubleClickedEvent()
SetEnteredEvent()
SetPressedEvent()
SetViewportEnteredEvent()
SetCurrentItemChangedEvent()
SetItemCollapsedEvent()
SetItemExpandedEvent()
QComboBox SetActivatedEvent()
SetCurrentIndexChangedEvent()
SetEditTextChangedEvent()
SetHighlightedEvent()
QTabWidget SetCurrentChangedEvent()
SetTabCloseRequestedEvent()
QTableWidget SetCellActivatedEvent()
SetCellChangedEvent()
SetCellClickedEvent()
SetCellDoubleClickedEvent()

SetCellEnteredEvent()
SetCellPressedEvent()
SetCurrentCellChangedEvent()
SetCurrentItemChangedEvent()
QProgressBar SetValueChangedEvent()
QSpinBox SetValueChangedEvent()
QSlider SetActionTriggeredEvent()
SetRangeChangedEvent()
SetSliderMovedEvent()
SetSliderPressedEvent()
SetSliderReleasedEvent()
SetValueChangedEvent()
QDial SetActionTriggeredEvent()
SetRangeChangedEvent()
SetSliderMovedEvent()
SetSliderPressedEvent()
SetSliderReleasedEvent()
SetValueChangedEvent()
QWebView SetLoadFinishedEvent()
SetLoadProgressEvent()
SetLoadStartedEvent()
SetTitleChangedEvent()
SetUrlChangedEvent()
QCheckBox SetStateChangedEvent()
SetClickedEvent()
SetPressedEvent()
SetReleasedEvent()
SetToggledEvent()
QRadioButton SetClickedEvent()
SetPressedEvent()
SetReleasedEvent()
SetToggledEvent()
QButtonGroup SetButtonClickedEvent()
SetButtonPressedEvent()
SetButtonReleasedEvent()
QVideoWidget SetBrightnessChangedEvent()
SetContrastChangedEvent()
SetFullScreenChangedEvent()
SetHueChangedEvent()
SetSaturationChangedEvent()
QTimer SetTimeoutEvent()

QTcpServer SetAcceptErrorEvent()
SetNewConnectionEvent()
QIODevice SetAboutToCloseEvent()
SetBytesWrittenEvent()
SetReadChannelFinishedEvent()
SetReadyReadEvent()
QAbstractSocket SetConnectedEvent()
SetDisconnectedEvent()
SetErrorEvent()
SetHostFoundEvent()
SetProxyAuthenticationRequiredEvent()
SetStateChangedEvent()
QTcpSocket SetConnectedEvent()
SetDisconnectedEvent()
SetErrorEvent()
SetHostFoundEvent()
SetProxyAuthenticationRequiredEvent()
SetStateChangedEvent()
SetAboutToCloseEvent()
SetBytesWrittenEvent()
SetReadChannelFinishedEvent()
SetReadyReadEvent()
QColorDialog SetColorSelectedEvent()
SetCurrentColorChangedEvent()
QNetworkAccessManager SetFinishedEvent()
QThread SetStartedEvent()
SetFinishedEvent()
52.56 Methods to use Events with Events Filter
RingQt deﬁne a new class called QAllEvents that help you in using Events Filter
The next table presents the methods that we have
Methods to get parameters Class Name
getKeyCode() –> Number QAllEvents
getx() –> Number
gety() –> Number
getglobalx() –> Number
getglobaly() –> Number
getbutton() –> Number
getbuttons() –> Number
The next table presents the methods that we have to use events.
52.56. Methods to use Events with Events Filter 527

Method Name Class Name
setKeyPressEvent(cEvent) QAllEvents
setMouseButtonPressEvent(cEvent)
setMouseButtonReleaseEvent(cEvent)
setMouseButtonDblClickEvent(cEvent)
setMouseMoveEvent(cEvent)
setCloseEvent(cEvent)
setContextMenuEvent(cEvent)
setDragEnterEvent(cEvent)
setDragLeaveEvent(cEvent)
setDragMoveEvent(cEvent)
setDropEvent(cEvent)
setEnterEvent(cEvent)
setFocusInEvent(cEvent)
setFocusOutEvent(cEvent)
setKeyReleaseEvent(cEvent)
setLeaveEvent(cEvent)
setNonClientAreaMouseButtonDblClickEvent(cEvent)
setNonClientAreaMouseButtonPressEvent(cEvent)
setNonClientAreaMouseButtonReleaseEvent(cEvent)
setNonClientAreaMouseMoveEvent(cEvent)
setMoveEvent(cEvent)
setResizeEvent(cEvent)
setWindowActivateEvent(cEvent)
setWindowBlockedEvent(cEvent)
setWindowDeactivateEvent(cEvent)
setWindowStateChangeEvent(cEvent)
setWindowUnblockedEvent(cEvent)
52.57 The Difference between Qt and RingQt
1. RingQt use simple methods to set the code that will be executed for events.
Syntax:
Set<Event_Name>Event(cEventCode)
2. RingQt change the name of some methods to avoid conﬂict with Ring Keywords.
The next table present these little changes
52.57. The Difference between Qt and RingQt 528

Class Name Qt Method Name RingQt Method Name
QWebView load loadpage
QMediaPlaylist load loadﬁle
QMediaPlaylist next movenext
QPainter end endpaint
QPicture load loadﬁle
QLineEdit end endtext
QDialog done donedialog
QTextDocument end enddoc
QTextBlock next nextblock
QSqlQuery next movenext
QImage load loadimage
QNetworkAccessManager get getvalue
QNetworkAccessManager put putvalue
QThread exit exitfromthread
QRegularExpressionMatchIterator next nextitem
QCamera load loadcamera
52.58 RingQt Classes and their Qt Documentation
Qt Documentation : http://doc.qt.io/qt-5/classes.html
See the “RingQt Classes and Methods Reference” chapter for supported classes and methods.
52.59 New Classes names - Index Start from 1
We added new classes to RingQt - another version of classes where the class names doesn’t start with the “q” letter
Also updated methods so the index start from 1 when we deal with the GUI controls like
• ComboBox
• ListWidget
• TableWidget
• TreeWidget
These classes are inside guilib.ring under the package name : System.GUI
To use it
load "guilib.ring"
import System.GUI
This doesn’t have any effect on our previous code, It’s just another choice for better code that is consistent with Ring
rules.
Also the form designer is updated to provide us the choice between using classes where (index start from 0) or (index
start from 1)
Example (Uses the Form Designer)
1. https://github.com/ring-lang/ring/blob/master/applications/formdesigner/tests/indexstart/indexstartView.ring
2. https://github.com/ring-lang/ring/blob/master/applications/formdesigner/tests/indexstart/indexstartController.ring
52.58. RingQt Classes and their Qt Documentation 529

CHAPTER
FIFTYTHREE
BUILDING RINGQT APPLICATIONS FOR MOBILE
In this chapter we will learn about Building RingQt Applications for Mobile.
53.1 Download Requirements
Check the next link : http://doc.qt.io/qt-5/androidgs.html
Download
• The Android SDK Tools
https://developer.android.com/studio/index.html
• The Android NDK
https://developer.android.com/ndk/index.html
• Apache Ant v1.8 or later
http://ant.apache.org/bindownload.cgi
• Java SE Development Kit (JDK) v6 or later
http://www.oracle.com/technetwork/java/javase/downloads/jdk7-downloads-1880260.html
53.2 Update the Android SDK
Update the Android SDK to get the API and tools packages required for development
53.3 Install Qt for Android
• You can install Qt for Android from the next link
https://download.qt.io/archive/qt/5.5/5.5.1/
• Run Qt Creator, Select Tools > Options > Android to add the Android NDK and SDK paths.
http://doc.qt.io/qtcreator/creator-developing-android.html
• Using Qt Creator Open the project
Folder : ring/android/ringqt/project
Project ﬁle : project.pro
530

• You will find the code in resourcestest.ring
You can modify the code then build and run for Desktop or Mobile.
53.4 Comments about developing for Android using RingQt
1. The main project file is main.cpp
This file load Ring Compiler/Virtual Machine and RingQt
Then copy files during the runtime from the resources to temp. folder
Then run the test.ring
Through main.cpp you can extract more files from the resources to temp. folder once you add them
(create projects with many files).
2. The next functions are missing from this Ring edition
• Database (ODBC, SQLite & MySQL)
• Security and Internet functions (LibCurl & OpenSSL)
• RingAllegro (Allegro Library)
• RingLibSDL (LibSDL Library)
Just use Qt Classes through RingQt.
For database access use the QSqlDatabase Class
Note: All of the missing libraries ((LibCurl, OpenSSL & Allegro) can be compiled for Android, but they are not
included in this Qt project.
3. use if isandroid() when you want to modify the code just for android
53.4. Comments about developing for Android using RingQt 531

Example:
if isandroid()
// Android code
else
// other platforms
ok
(4) Sometimes you will ﬁnd that the button text/image is repeated in drawing ! it’s Qt problem that you can avoid
using the next code.
if isandroid()
setStyleSheet("
border-style: outset;
border-width: 2px;
border-radius: 4px;
border-color: black;
padding: 6px;")
ok
5. Always use Layouts instead of manual setting of controls position and size.
This is the best way to get the expected user interface to avoid problems like (controls with small/extra size)
6. When you deal with Qt Classes you can determine the images from resources (you don’t need to copy them
using main.cpp)
Example:
if isandroid()
mypic = new QPixmap(":/resources/cardsimage")
else
mypic = new QPixmap("cards.jpg")
ok
In the previous example, cards.jpg is added to the resources then we write the “cardsimage” as alias for “cards.jpg”
53.4. Comments about developing for Android using RingQt 532

CHAPTER
FIFTYFOUR
OBJECTS LIBRARY FOR RINGQT APPLICATION
In this chapter we will learn about the objects library for RingQt applications.
Ring comes with the Objects library for RingQt applications. Instead of using global variables for windows objects
and connecting events to objects using the object name, the Objects Library will manage the GUI objects and will
provide a more natural API to quickly create one or many windows from the same class and the library provide a way
to quickly set methods to be executed when an event is ﬁred. Also the library provide a natural interface to quickly
use the parent or the caller windows from the child or sub windows.
The Objects Library is designed to be used with the MVC Design Pattern.
The Objects Library is merged in RingQt so you can use it directly when you use RingQt
54.1 Library Usage
• Use the Open_Window(cWindowControllerClassName) function to open new Windows
• Create at least Two Classes for each window, The Controller Class and the View Class
• Create each controller class from the WindowsControllerParent Class
• Create each view class from the WindowsViewParent Class
• Use the Last_Window() function to get the object of the last window created (The Controller object).
• When you call a sub window, use the SetParentObject() method and pass the self object.
• In the View Class, To determine the event method use the Method(cMethodName) function.
• The Method(cMethodName) function determine the method in the controller class that will be executed.
• Each controller class contains by default the CloseAction() method that you can call to close the window.
• You don’t need to call the Show() Method for each window, When you use Open_Window() It will be called.
• In the view class, Deﬁne the GUI window object as an attribute called win.
• You can use Open_WindowNoShow() to avoid displaying the window.
• You can use Open_WindowAndLink() to quickly get methods to access the windows.
54.2 Example
In the next example we will create two types of windows.
• Main Window contains a button. When the user click on the button a sub window will be opened.
533

• The User Can click on the button many times to open many sub windows.
• Each Sub Window contains Two buttons.
• The ﬁrst button in the sub window change the Main and the Sub Windows Titles.
• The second button in the sub window close the Sub Window.
load "guilib.ring"
new qApp {
open_window( :MainWindowController )
exec()
}
class MainWindowController from WindowsControllerParent
oView = new MainWindowView
func SubWindowAction
Open_window( :SubWindowController )
Last_Window().SetParentObject(self)
class MainWindowView from WindowsViewParent
win = new qWidget() {
SetWindowTitle("Main Window")
btnSub = new qPushButton(win) {
setText("Sub Window")
setClickEvent( Method( :SubWindowAction ) )
}
resize(400,400)
}
class SubWindowController from WindowsControllerParent
oView = new SubWindowView
func SetMainWindowTitleAction
Parent().oView.win.SetWindowTitle("Message from the Sub Window")
oView.win.SetWindowTitle("Click Event Done!")
class SubWindowView from WindowsViewParent
win = new qWidget() {
SetWindowTitle("Sub Window")
btnMsg = new qPushButton(win) {
setText("Set Main Window Title")
setClickEvent( Method( :SetMainWindowTitleAction ) )
}
btnClose = new qPushButton(win) {
Move(200,0)
setText("Close")
setClickEvent( Method( :CloseAction ) )
}
resize(400,400)
}
The next screen shot after creating three sub windows.
54.2. Example 534

The next screen shot after clicking on the button in each sub window.
54.2. Example 535

54.3 Open_WindowAndLink() Function
We can use the Open_WindowAndLink() function to connect between the application windows, pass messages (call
methods) between the objects.
This function uses Meta-programming to define dynamic methods in the Caller Class to use the dynamic objects of
other windows that we create.
Example : (Uses the Form Designer)
First Window
1. https://github.com/ring-lang/ring/blob/master/applications/formdesigner/tests/twowindowspart5/firstwindowView.ring
2. https://github.com/ring-lang/ring/blob/master/applications/formdesigner/tests/twowindowspart5/firstwindowController.ring
Second Window
1. https://github.com/ring-lang/ring/blob/master/applications/formdesigner/tests/twowindowspart5/secondwindowView.ring
2. https://github.com/ring-lang/ring/blob/master/applications/formdesigner/tests/twowindowspart5/secondwindowController.ring
54.3. Open_WindowAndLink() Function 536

In the next code for example (from FirstWindowController.ring)
The Open_WindowAndLink() will create an object from the SecondWindowController Class
Then will add the Method : SecondWindow(), IsSecondWindow() Methods to the FirstWindowController Class
Also will add the Method : FirstWindow(), IsFirstWindow() Methods to the SecondWindowController Class
So the SendMessage() method in FirstWindowController class can use the SecondWindow() method to access the
object.
This is more simple than using Last_Window(), Parent() and SetParentObject() methods.
class firstwindowController from windowsControllerParent
oView = new firstwindowView
func OpenSecondWindow
Open_WindowAndLink(:SecondWindowController,self)
func SendMessage
if IsSecondWindow()
SecondWindow().setMessage("Message from the first window")
ok
func setMessage cMessage
oView.Label1.setText(cMessage)
54.4 Objects Library Source Code
The library source code is very simple, You can check the source code ﬁles
• https://github.com/ring-lang/ring/blob/master/extensions/ringqt/objectslib/objects.ring
• https://github.com/ring-lang/ring/blob/master/extensions/ringqt/objectslib/subwindows.ring
54.4. Objects Library Source Code 537

CHAPTER
FIFTYFIVE
USING THE FORM DESIGNER
In this chapter we will learn about using the Form Designer.
We can run the From Designer from Ring Notepad
From the Menubar in Ring Notepad - View Menu - We can Show/Hide the Form Designer window.
Also we can run the Form Designer in another window.
From the Ring Notepad - Tools Menu - Select the Form Designer.
538

55.1 The Designer Windows
• Toolbox : To select controls to be added to the window.
• Properties : To set the properties of the active window or controls.
• Design Region : To select, move and resize the window and the controls.
55.2 The Toolbox
We have many buttons.
• Lock : We can use it to draw many controls of the same type quickly.
• Select : We can use it to select a control in the Design Region
• Controls Buttons : Select a control to be added to the window.
55.3 The Properties
• When we select the window or one control, We will have the selected object properties.
• Also In the properties window we have a combobox to select the active control.
• Some properties provide a button next to the property value. We can click on the button to get more options.
• When we select more than one control, We will have options for multi-selection
55.1. The Designer Windows 539

55.4 Running Forms
When we save the form file (*.rform), The Form Designer will create two Ring files
• The Controller Class
• The View Class
For example, if the form file is helloworld.rform
The form designer will generate two files
• helloworldcontroller.ring
• helloworldview.ring
To run the program, Open the controller class file then click the Run button (CTRL+F5)
Tip: When you open a form using Ring Notepad, the controller class will be opened automatically, So we can press
(CTRL+F5) or click on the Run button while the form designer window is active.
55.5 Events Code
1. Just type the method name in the event property.
55.4. Running Forms 540

(2) Then write the method code in the controller class.
55.5. Events Code 541

In this example we write
func CloseWindow
oView.win.close()
Where inside the controller class, We uses the oView object to access the form.
Another Example :
55.5. Events Code 542

The Event Code
func SayHello
oView {
LineEdit2.setText("Hello "+ LineEdit1.text() )
}
55.6 Keyboard Shortcuts
After selecting one or group of controls
• Use the Arrows (Up, Down, Left and Right) to move them around.
• Shift + the Arrows (Up, Down, Left and Right) to Resize the controls.
• Del button to delete the controls.
• CTRL+SHIFT+V to Duplicate the controls.
55.7 Menubar Designer
From the Window properties we can open the Menubar Designer
55.6. Keyboard Shortcuts 543

55.8 Window Flags
From the Window properties we can open the Window Flags window.
55.8. Window Flags 544

55.9 Entering Items
For some controls like the List Widget we can enter items separated by comma ‘,’
55.10 Using Layouts
1. To use layouts, At ﬁrst add the layout control to the window.
2. Use the window “Set Layout” property to determine the main layout.
3. From the layout properties determine the controls and the layout type.
55.11 More Samples and Tests
Check the folder : ring/applications/formdesigner/tests
Online : https://github.com/ring-lang/ring/tree/master/applications/formdesigner/tests
55.9. Entering Items 545

CHAPTER
FIFTYSIX
SCOPE RULES FOR VARIABLES AND ATTRIBUTES
In this chapter we will learn about scope rules and how Ring find variables.
Also we will learn about conflicts and how to solve/avoid them.
The next information are important once you start developing large applications using Ring
These application may uses
• Global variables (Try to avoid them)
• Classes (Object-Oriented)
• braces { } to access objects
• Declarative Programming
• Natural Programming
56.1 Three Scopes
In Ring we have three scopes :-
1. Public/Global Scope - Each variable you define in the statements part (before functions and classes)
2. Object Scope - When you are inside an object (Inside class method or using { } to access the object )
3. Local Scope - Related to functions and methods
56.2 Defining Variables and Variables Access
1. Ring uses lexical scoping, i.e. the scope of the variable is based on where we defined the variable.
2. Inside braces { } when you access an object, You will change the current active object scope to this object scope
but you still can access the global scope and the local scope.
3. After the ‘Class’ keyword and the class name, when you write variable names to be defined as attributes, You
still can access the global scope.
In this region (class region - after the class name and before methods) we have
• Global Scope —-> The Global Scope
• Object Scope —-> The Object Scope
• Local Scope —-> The Object Scope
546

Note: Since the local scope in the class region point also to the object scope in this region, we can use nested braces
and still have access to the object scope of the class through the local scope.
Tip: You can create windows and controls as attibutes by defining them in this region.
Tip: In the class region if you created objects and used braces {} to access them then using self.attribute inside braces
will use the class (not the object that you access) because you have access to the class through the local scope.
4. Function Parameters are automatically defined in the local scope.
56.3 How Ring find the variable?
1 - Search First in the Local Scope
if not found !
2 - Search in the Object Scope
if not found !
3 - Search in the public scope
if not found —-> Runtime Error
if found —-> Check if we can do optimization to avoid searching next time (Cache / Pointers for performance).
56.4 Using Object.Attribute
When we use object.attribute the search will be in the object attributes only.
I.e. no search will be done in the local scope or in the global scope for the object attribute.
Note: Using self.attribute will search for the first self before searching for attributes.
56.5 The Self Object
The self object is a reference to the current object that we can use from the class methods.
When we are inside class method and use Self we mean the object that will be created from this class.
Inside the class methods if we used Braces { } this will change the current object scope and self will be changed also
inside braces to reference the object that we access using Braces.
Inside the Class Region (after the class name and before any method) we have access to the object through the object
scope and the local scope also. In this region using Self will always be a reference to the class object. if we used
Braces to change the object scope then used Self inside Braces, Also self will be a reference to the class object (not
the object that we already access using braces) because in the class region we have :-
• Global Scope —> Global Scope
• Object Scope —> Object Scope
56.3. How Ring find the variable? 547

The Ring programming language version 1.4.1 book - Part 19 of 31

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The Ring programming language version 1.4.1 book - Part 19 of 31