This document provides documentation for Ring version 1.4.1. It discusses why list indexes start at 1 in Ring rather than 0 as in some other languages. It also covers topics like constructors, what happens when an object is created, using getter and setter methods, and including multiple source files in a project. Various code examples are provided to illustrate concepts around classes, objects, functions, and other Ring features.

1. Ring Documentation, Release 1.4.1
Output
1
2
3
4
5
X value = 10
71.18 Why the list index start from 1 in Ring?
It’s about how we count in the real world, when we have three apples in our hand
we say 1 2 3
We don’t start from 0
The question must be why the other languages start from 0 ?
The answer is, because this is related to the machine and how we deal with values and memory address.
Example
we have array called myarray[5]
In memory : myarray will have an address
The first item will be stored in that address
The second item will come after that address and so on
Now when we need to point to the first item we need the address of myarray
So we type myarray[0] because myarray + 0 result will still point to the first item
for the second item myarray[1] because myarray + 1 result will point to the second item and so on
In Low Level languages or languages near to the machine it’s good to be like this
But for high level language designed for applications it’s better to be natural
Example
mylist = [1,2,3,4,5]
for x = 1 to len(mylist)
see x + nl
next
In the previous example we start from 1 to the length of the array if the index starts from 0 we will write
for x = 0 to len(mylist)-1
or remember the for loop in other languages
for(x=0 ; x<nMax ; x++ )
You will use the < operator !
71.19 Is there constructor methods in Ring?
When you create new object for example
71.18. Why the list index start from 1 in Ring? 818

2. Ring Documentation, Release 1.4.1
new point
1 - Ring will allocate dynamic memory space to be used for the new object attributes that Ring doesn’t know anything
about them.
2 - Ring will change the current local scope and the current object scope to use the object state created in step (1)
3 - Ring will move the execution to the class Region (After the class name and before any methods)
4 - Any Instructions/Code in the class region will be executed as any Ring code
5 - Control is moved from the class region to the location of (new point) once we reach the end of the class region or
we uses a Return command.
So All attributes that added to the object are dynamic attributes, this mean that you can control what attributes will be
added through the runtime.
Example:
$3D = False
see new point
$3D = True
see new point
class point
x y
if not $3D return ok
z
Output:
x: NULL
y: NULL
x: NULL
y: NULL
z: NULL
You have an option to call init() method directly when you create a new object
This method can do anything with the object attributes as it will be called after creating the object and executing the
class region code.
p1 = new point3d(100,200,300)
see p1
class point3d
x y z
func init p1,p2,p3
x=p1 y=p2 z=p3
71.20 What happens when we create a new object?
1- When you create an object, the class region code will be executed and you will have the object attributes based on
the code in that region
2- Ring don’t care about the object methods until you start calling a method
3- When you call a method, Ring will check the object class and the class parent (if you are using inheritance) and
will collect the methods for you to be used now or later from any object that belong to the same class.
71.20. What happens when we create a new object? 819

3. Ring Documentation, Release 1.4.1
4- Since methods are dynamic and each object get the method from the class, you can after creating objects, add new
methods and use it with the object or any object created or will be created from the same class.
Example:
o1 = new point {x=10 y=20 z=30}
o2 = new point {x=100 y=200 z =300}
addmethod(o1,"print", func { see x + nl + y + nl + z + nl } )
o1.print()
o2.print()
class point x y z
Output:
10
20
30
100
200
300
71.21 Can we use the attributes by accessing the Getter and Setter
methods?
Yes we can, The setter/getter methods are called automatically when you start using the attributes from outside the
class Also you can call the methods instead of using the attributes. It’s your choice.
Example:
o1 = new Developer
o1.name = "Mahmoud" see o1.name + nl
o1 { name = "Gal" see name }
o1 { name = "Bert" see name }
o1.setname("Marino")
see o1.getname()
Class Developer
name language = "Ring Programming Language"
func setname value
see "Message from SetName() Function!" + nl
name = value + " - " + language
func getname
see "Message from GetName() Function!" + nl + nl
return "Mr. " + name + nl
Output
Message from SetName() Function!
Message from GetName() Function!
71.21. Can we use the attributes by accessing the Getter and Setter methods? 820

4. Ring Documentation, Release 1.4.1
Mr. Mahmoud - Ring Programming Language
Message from SetName() Function!
Message from GetName() Function!
Mr. Gal - Ring Programming Language
Message from SetName() Function!
Message from GetName() Function!
Mr. Bert - Ring Programming Language
Message from SetName() Function!
Message from GetName() Function!
Mr. Marino - Ring Programming Language
71.22 Why should a search of global names be made while defining
the class attributes?
The question is why we don’t avoid conflicts with global variable names when we define the class attributes ?
At first remember that using the optional $ mark in the global variables names solve the problem. Also using the Main
function and avoiding global variables may help.
The Answer:
Ring is a dynamic language
We can in the run-time determine the class attributes (Add/Remove)
We can execute (any code) while defining the class attributes
Example (1)
oPerson = new Person
Class Person
See "Welcome to the Ring language"
Example (2)
Customize attributes based on global variable value
$debug = true
oPerson = new Person
see oPerson
Class Person
if $debug date=date() time=time() ok
In the previous example when we have the $debug flag set to true, we will add the Date and Time attributes to the
object state.
Example (3)
Store the object index based on global variable
$ObjectsCount = 0
oPerson = new Person
see oPerson
oPerson2 = new Person
see oPerson2
71.22. Why should a search of global names be made while defining the class attributes? 821

5. Ring Documentation, Release 1.4.1
Class Person
$ObjectsCount++
nIndex = $ObjectsCount
Output:
nindex: 1.000000
nindex: 2.000000
Common Example:
• Connect to the database then get table columns (Using global Variable/Object).
• Create class attributes based on the column names.
• Later when you modify the database - you may don’t need to modify your code.
It’s flexibility but remember that power comes with great responsibility.
71.23 Why Ring doesn’t avoid the conflict between Global Variables
and Class Attributes Names?
In this use case we have
1 - Global Variable defined without a special mark like $
2 - Class contains Attributes defined using a special syntax (where we type the attribute name directly after the class)
3 - The Attributes are defined in the class region that allows writing code and using global variables
If I will accepted your proposal about changing how Ring find variables in the class region I must break one of the
previous three features which will lead to more problems that are more important than this problem.
I don’t like changing the feature number (1) because I would like to keep Ring code more clean and let the programmer
decide when to use $ or not.
I don’t like changing the feature number (2) because I like this feature and I don’t like forcing the programmer to type
self.attribute
I don’t like changing the feature number (3) because it’s very important in many applications to access global variables
in the class region.
So what was my decision ?
I decided to leave this case for the programmer who will decide what to do to avoid this special case
1 - The programmer can avoid using global variables (Better) and can use the Main function (Optional)
2 - The programmer can use $ before the variable name or any mark like global_ or g_
3 - The programmer can use self.attribute after the class name to define the attributes
In general, for small programs you can use global variables and functions. For large programs, use classes and objects
and small number of global variables or avoid them at all.
71.24 Where can I write a program and execute it?
Run the Ring Notepad where you can write/execute programs.
If you want to run programs using the command line
71.23. Why Ring doesn’t avoid the conflict between Global Variables and Class Attributes Names?822

6. Ring Documentation, Release 1.4.1
Add Ring/bin folder to the path then
71.25 How to get the file size using ftell() and fseek() functions?
The next function can be used to get the file size without reading the file!
func getFileSize fp
C_FILESTART = 0
C_FILEEND = 2
fseek(fp,0,C_FILEEND)
nFileSize = ftell(fp)
fseek(fp,0,C_FILESTART)
return nFileSize
Note: The previous function take the fp (file pointer) as parameter, We can get the fp from opening the file using
fopen() function.
fp = fopen("filename","r")
see "File Size : " + getFileSize(fp) + nl
Another solution (Read the file)
see len(read("filename"))
71.26 How to get the current source file path?
We can use the next function to get the current source file path then we can add the path variable to the file name
cPath = CurrentPath()
func currentpath
cFileName = filename()
for x = len(cFileName) to 1 step -1
if cFileName[x] = "/"
return left(cFileName,x-1)
ok
next
return cFileName
71.27 What about predefined parameters or optional parameters in
functions?
if you want to use predefined parameters or optional parameters Just accept a list that works like hash/dictionary
Example
sum([ :a = 1, :b = 2])
sum([ :a = 1 ])
sum([ :b = 2 ])
func sum pList
if plist[:a] = NULL pList[:a] = 4 ok
71.25. How to get the file size using ftell() and fseek() functions? 823

7. Ring Documentation, Release 1.4.1
if plist[:b] = NULL pList[:b] = 5 ok
see pList[:a] + pList[:b] + nl
Output
3
6
6
71.28 How to print keys or values only in List/Dictionary?
If you want to print keys only or values only just select the index of the item (one or two).
Example
C_COUNTRY = 1
C_CITY = 2
mylist = [
:KSA = "Riyadh" ,
:Egypt = "Cairo"
]
for x in mylist
see x[C_COUNTRY] + nl
next
for x in mylist
see x[C_CITY] + nl
next
Output
ksa
egypt
Riyadh
Cairo
71.29 Why I get a strange result when printing nl with lists?
In the next code
list = 1:5 # list = [1,2,3,4,5]
see list + nl
New Line will be added to the list then the list will be printed, the default print of the lists will print a newline at the
end, You added new newline and You have now 2 newlines to be printed.
See <Expr>
The see command just print the final result of the expression, the expression will be evaluated as it
nl = char(13) + char(10) # just a variable that you can change to anything !
The + is an operator
71.28. How to print keys or values only in List/Dictionary? 824

8. Ring Documentation, Release 1.4.1
string + string ---> new string
string + number ---> new string
number + number ---> new number
number + string ---> new number
list + item —> nothing new will be created but the item will be added to the same list
Exception
number + nl ?> New String
This exception is added to easily print numbers then new line.
No need for this with printing lists because after printing the last item we already get a new line.
71.30 Could you explain the output of the StrCmp() function?
At first remember that you can check strings using ‘=’ operator directly.
see strcmp("hello","hello") + nl +
strcmp("abc","bcd") + nl +
strcmp("bcd","abc") + nl
if the two strings are the same then it returns 0
abc and bcd aren’t the same. in the second line it returns -1 and in the third line it returns 1
In the second line we compare between “abc” and “bcd”
Not equal because the first letter in “abc” = “a” and the first letter in “bcd” = “b”
So we have “a” != “b” and “a” < “b”
So we get output = -1
In the third line we have “bcd” and “abc”
the first letter in “bcd” is “b” and the first letter in “abc” is “a”
So we have “b” != “a” and “b” > “a”
So we get output = 1
Note: ASCII(“a”) = 97 and ASCII(“b”) = 98 So “a” < “b” because 97 < 98
71.31 How to use many source code files in the project?
Example:
I have the next folder
C:LRing
Contains the next files
C:LRingt1.ring
C:LRingmylib.ring
C:LRinglibsmylib2.ring
71.30. Could you explain the output of the StrCmp() function? 825

9. Ring Documentation, Release 1.4.1
The file t1.ring contains the next code
load "mylib.ring"
load "libsmylib2.ring"
myfunc()
test()
The file mylib.ring contains the next code
func myfunc
see "message from myfunc"+nl
The file libsmylib2.ring contains the next code
func test
see "message from test" + nl
from the folder C:LRing
If Ring is not added to the path you can add it or use the next command
set path=%path%;c:ringbin;
Where c:ring is the Ring folder
Now run
Ring t1.ring
Output
message from myfunc
message from test
71.32 Why this example use the GetChar() twice?
The GetChar() function accept one character from the keyboard buffer
In this example
While True
See "
Main Menu
(1) Say Hello
(2) Exit
"
Option = GetChar()
GetChar() GetChar() # End of line
# the previous two lines can be replaced with the next line
# Give Option
if Option = 1
see "Enter your name : " give cName
see "Hello " + cName
else
bye
ok
End
71.32. Why this example use the GetChar() twice? 826

10. Ring Documentation, Release 1.4.1
We uses GetChar() Three times
The first time we get the user option
Option = GetChar()
But in the second and the third times (We accept the new line characters from the buffer)
GetChar() GetChar() # End of line
Example : when the user select the option number 1 then press ENTER
We have Three Characters
• The first character is : Number 1
• The second character is : CHAR(13)
• The third character is : CHAR(10)
Because Windows uses CHAR(13) and CHAR(10) for each new line ( i.e. CR+LF )
71.33 How to use NULL and ISNULL() function?
when we try to use uninitialized variable in the Ring programming language, we get a clear runtime error message
Example
See x
Output
Line 1 Error (R24) : Using uninitialized variable : x
in file testsseeuninit.ring
The same happens when you try to access uninitialized attributes
Example
o1 = new point
see o1
see o1.x
class point x y z
Output
x: NULL
y: NULL
z: NULL
Line 3 Error (R24) : Using uninitialized variable : x
in file testsseeuninit2.ring
if you want to check for the error, just use Try/Catch/End
Try
see x
Catch
See "Sorry, We can't use x!" + nl
Done
Output
71.33. How to use NULL and ISNULL() function? 827

11. Ring Documentation, Release 1.4.1
Sorry, We can't use x!
Now we will talk about NULL and ISNULL()
Since we get error message when we deal with uninitialized variables
We can check these errors using Try/Catch/Done, So we uses NULL and ISNULL() for dealing with Strings.
NULL is a variable contains an empty string
ISNULL() is a function that returns true (1) if the input is an empty string or just a string contains “NULL”
This because we need to test these values (empty strings) and strings contains “NULL” that sometimes come from
external resource like DBMS.
Example
See IsNull(5) + nl + # print 0
IsNull("hello") + nl + # print 0
IsNull([1,3,5]) + nl + # print 0
IsNull("") + nl + # print 1
IsNull("NULL") # print 1
71.34 How to print lists that contains objects?
In this example we will see how we can print a list contains objects.
aList = [[1,2,3] , new point(1,2,3), new point(1,2,3)]
see "print the list" + nl
see alist
see "print the item (object)" + nl
see alist[2]
class point x y z
func init p1,p2,p3 x=p1 y=p2 z=p3
Output
print the list
1
2
3
x: 1.000000
y: 2.000000
z: 3.000000
x: 1.000000
y: 2.000000
z: 3.000000
print the item (object)
x: 1.000000
y: 2.000000
z: 3.000000
71.35 How to insert an item to the first position in the list?
To insert an item we can use the insert(aList,nIndex,Value) function.
71.34. How to print lists that contains objects? 828

12. Ring Documentation, Release 1.4.1
aList = 1:5
insert(aList,0,0)
See aList # print numbers from 0 to 5
71.36 How to print new lines and other characters?
To print new line we can use the nl variable.
See "Hello" + nl
or we can use multi-line literal as in the next example
See "Hello
"
if we want to print other characters we can use the char(nASCII) function
See char(109) + nl + # print m
char(77) # print M
71.37 Why we don’t use () after the qApp class name?
When we use RingQt to create GUI application, we uses () after the class name when we create new objects for
example.
new qWidget() { setWindowTitle("Hello World") resize(400,400) show() }
but before doing that we create an object from the qApp class and we don’t use () after that
Load "guilib.ring"
app = new qApp
{
win=new qWidget()
{
setwindowtitle(:test)
show()
}
exec()
}
Using () after the class name means calling the init() method in the class and passing parameters to this method.
If we used () while no init() method in the class we get the expected error message.
The class qApp don’t have this method while the other classes have it because they need it to create an object using
a function that return a pointer to that object and this pointer will be stored in an attribute called pObject, for more
information see ring_qt.ring file which contains the classes.
71.38 Why the window title bar is going outside the screen?
When we write the next code
71.36. How to print new lines and other characters? 829

13. Ring Documentation, Release 1.4.1
Load "guilib.ring"
app = new qApp
{
win=new qWidget()
{
setwindowtitle(:test)
setGeometry(0,0,200,200)
show()
}
exec()
}
I would expect that the window will run at the point (0,0) with (200,200) size but the actual result is that the window
title bar is going outside the screen.
This is related to the behavior of Qt framework.
The next code will avoid the problem
load "guilib.ring"
new qApp {
new qWidget() {
move(0,0)
resize(200,200)
show()
}
exec()
}
71.39 How to create an array of buttons in GUI applications?
Check the next example:
Load "guilib.ring"
App1 = new qApp {
win1 = new qWidget() {
move(0,0)
resize(500,500)
new qPushButton(win1)
{
settext("OK")
setclickevent("click()")
}
btn1 = new qPushButton(win1)
{
setgeometry(100,100,100,30)
settext("Button1")
}
btn2 = new qPushButton(win1)
{
setgeometry(200,100,100,30)
settext("Button2")
}
71.39. How to create an array of buttons in GUI applications? 830

14. Ring Documentation, Release 1.4.1
button = [btn1, btn2]
show()
}
exec()
}
func click
button[1] { settext ("Button3") }
button[2] { settext ("Button4") }
71.40 How to Close a window then displaying another one?
This example demonstrates how to close a window and show another one
Load "guilib.ring"
app=new qApp
{
frmBefore=new Qwidget()
{
setWindowTitle("before!")
resize(300,320)
move(200,200)
button=new qPushButton(frmBefore)
{
setText("Close")
setClickEvent("frmBefore.close() frmMain.show()")
}
show()
}
frmMain=new Qwidget()
{
setWindowTitle("After!")
resize(300,320)
move(200,200)
}
exec()
}
71.41 How to create a Modal Window?
This example demonstrates how to create a modal window
load "guilib.ring"
app=new qApp
{
71.40. How to Close a window then displaying another one? 831

15. Ring Documentation, Release 1.4.1
frmStart=new Qwidget()
{
setWindowTitle("The First Window")
resize(300,320)
move(200,200)
button=new qPushButton(frmStart)
{
setText("Show Modal Window")
resize(200,30)
setClickEvent("frmModal.show()")
}
new qPushButton(frmStart)
{
setText("Close Window")
move(0,50)
resize(200,30)
setClickEvent("frmStart.Close()")
}
show()
}
frmModal =new Qwidget()
{
setWindowTitle("Modal Window")
resize(300,320)
move(200,200)
setparent(frmStart)
setwindowmodality(true)
setwindowflags(Qt_Dialog)
}
exec()
}
Related Documents
• http://doc.qt.io/qt-5/qtwidgets-widgets-windowflags-example.html
• http://doc.qt.io/qt-5/qt.html#WindowType-enum
• http://doc.qt.io/qt-5/qwindow.html#setParent
• http://doc.qt.io/qt-5/qt.html#WindowModality-enum
71.42 How can I disable maximize button and resize window?
Use the method setWindowFlags()
Load "guilib.ring"
app1 = new qapp {
win1 = new qwidget() {
setwindowtitle("First")
setgeometry(100,100,500,500)
71.42. How can I disable maximize button and resize window? 832

16. Ring Documentation, Release 1.4.1
new qpushbutton(win1) {
setgeometry(100,100,100,30)
settext("close")
setclickevent("app1.quit()")
}
new qpushbutton(win1) {
setgeometry(250,100,100,30)
settext("Second")
setclickevent("second()")
}
showmaximized()
}
exec()
}
func second
win2 = new qwidget() {
setwindowtitle("Second")
setgeometry(100,100,500,500)
setwindowflags(Qt_dialog)
show()
}
71.43 How to use SQLite using ODBC?
In Ring 1.1 and later versions we have native support for SQLite, so you don’t need to use it through ODBC.
Also we can access SQLite through RingQt.
The answer to your question
pODBC = odbc_init()
odbc_connect(pODBC,"DRIVER=SQLite3 ODBC Driver;Database=mydb.db;LongNames=0;"+
"Timeout=1000;NoTXN=0;SyncPragma=NORMAL;StepAPI=0;")
odbc_execute(pODBC,"create table 'tel' ('ID','NAME','PHONE');")
odbc_execute(pODBC,"insert into 'tel' values ('1','Mahmoud','123456');")
odbc_execute(pODBC,"insert into 'tel' values ('2','Ahmed','123456');")
odbc_execute(pODBC,"insert into 'tel' values ('3','Ibrahim','123456');")
odbc_execute(pODBC,"select * from tel") + nl
nMax = odbc_colcount(pODBC)
See "Columns Count : " + nMax + nl
while odbc_fetch(pODBC)
See nl
for x = 1 to nMax
see odbc_getdata(pODBC,x)
if x != nMax see " - " ok
next
end
odbc_disconnect(pODBC)
odbc_close(pODBC)
Output:
Columns Count : 3
71.43. How to use SQLite using ODBC? 833

17. Ring Documentation, Release 1.4.1
1 - Mahmoud - 123456
2 - Ahmed - 123456
3 - Ibrahim - 123456
The program will create the file : mydb.db
Note : when I print the odbc drivers I see the long list that includes
SQLite3 ODBC Driver - UsageCount=1
SQLite ODBC Driver - UsageCount=1
SQLite ODBC (UTF-8) Driver - UsageCount=1
And I’m using “SQLite3 ODBC Driver”.
71.44 Can I connect to dbase/harbour database?
You can connect to any database using ODBC
To connect to xbase files (*.DBF)
See "Using DBF Files using ODBC" + nl
pODBC = odbc_init()
See "Connect to database" + nl
odbc_connect(pODBC,"Driver={Microsoft dBase Driver (*.dbf)};"+
"datasource=dBase Files;DriverID=277")
See "Select data" + nl
odbc_execute(pODBC,"select * from tel.dbf")
nMax = odbc_colcount(pODBC)
See "Columns Count : " + nMax + nl
while odbc_fetch(pODBC)
See "Row data:" + nl
for x = 1 to nMax
see odbc_getdata(pODBC,x) + " - "
next
end
See "Close database..." + nl
odbc_disconnect(pODBC)
odbc_close(pODBC)
Output
Using DBF Files using ODBC
Connect to database
Select data
Columns Count : 3
Row data:
Ahmad - Egypt - 234567 - Row data:
Fady - Egypt - 345678 - Row data:
Shady - Egypt - 456789 - Row data:
Mahmoud - Egypt - 123456 - Close database...
Also you can connect to a Visual FoxPro database (requires installing Visual FoxPro driver)
See "ODBC test 6" + nl
pODBC = odbc_init()
See "Connect to database" + nl
odbc_connect(pODBC,"Driver={Microsoft Visual FoxPro Driver};"+
"SourceType=DBC;SourceDB=C:PWCT19ssbuildPWCTDATACH1Datamydata.dbc;")
71.44. Can I connect to dbase/harbour database? 834

18. Ring Documentation, Release 1.4.1
See "Select data" + nl
see odbc_execute(pODBC,"select * from t38") + nl
nMax = odbc_colcount(pODBC)
See "Columns Count : " + nMax + nl
while odbc_fetch(pODBC)
See "Row data:" + nl
for x = 1 to nMax
see odbc_getdata(pODBC,x) + " - "
next
end
See "Close database..." + nl
odbc_disconnect(pODBC)
odbc_close(pODBC)
71.45 Why setClickEvent() doesn’t see the object methods directly?
setClickEvent(cCode) take a string contains code. The code will be executed when the event happens.
Ring support Many Programming Paradigms like Procedural, OOP, Functional and others.
But when you support many paradigms at the language level you can’t know which paradigm will be used so you have
two options
1. Provide General Solutions that works with many programming paradigms.
2. Provide Many Specific solutions where each one match a specific paradigm.
setClickEvent() and others belong to (General Solutions that works with many programming paradigms).
You just pass a string of code that will be executed without any care about classes and objects.
This code could be anything like calling a function, calling a method and setting variable value.
Some other languages force you to use OOP and call methods for events. Also some other languages uses anonymous
functions that may get parameters like the current object.
Now we have the general solution (not restricted with any paradigm), In the future we may add specific solutions that
match specific paradigms (OOP, Functional, Declarative and Natural).
71.46 Why I get Calling Function without definition Error?
Each program follow the next order
1 - Loading Files 2 - Global Variables and Statements 3 - Functions 4 - Packages, Classes and Methods
So what does that mean ?
1. **** No Functions comes After Classes ****
2. **** No command is required to end functions/methods/classes/packages ****
Look at this example
See "Hello"
test()
func test
see "message from the test function!" + nl
class test
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In the previous example we have a function called test() so we can call it directly using test()
In the next example, test() will become a method
See"Hello"
test() # runtime error message
class test
func test # Test() now is a method (not a function)
see "message from the test method!" + nl
The errors comes when you define a method then try calling it directly as a function.
The previous program must be
See"Hello"
new test { test() } # now will call the method
class test
func test # Test() now is a method (not a function)
see "message from the test method!" + nl
71.47 Can Ring work on Windows XP?
Ring can work on Windows XP and load extensions without problems.
Just be sure that the extension can work on Windows XP and your compiler version support that (modern compilers
requires some flags to support XP)
Check this topic https://blogs.msdn.microsoft.com/vcblog/2012/10/08/windows-xp-targeting-with-c-in-visual-studio-
2012/
For example, We added
/link /SUBSYSTEM:CONSOLE,"5.01"
To the batch file to support Windows XP
See : https://github.com/ring-lang/ring/blob/master/src/buildvccomplete.bat
71.48 How to extend RingQt and add more classes?
You have many options
In general you can extend Ring using C or C++ code
Ring from Ring code you can call C Functions or use C++ Classes & Methods
This chapter in the documentation explains this part in the language http://ring-
lang.sourceforge.net/doc/extension.html
For example the next code in .c file can be compiled to a DLL file using the Ring library (.lib)
#include "ring.h"
RING_FUNC(ring_ringlib_dlfunc)
{
printf("Message from dlfunc");
}
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RING_API void ringlib_init(RingState *pRingState)
{
ring_vm_funcregister("dlfunc",ring_ringlib_dlfunc);
}
Then from Ring you can load the DLL file using LoadLib() function then call the C function that called dlfunc() as
any Ring function.
See "Dynamic DLL" + NL
LoadLib("ringlib.dll")
dlfunc()
Output
Dynamic DLL
Message from dlfunc
When you read the documentation you will know about how to get parameters like (strings, numbers, lists and objects)
And how to return a value (any type) from you function.
From experience, when we support a C library or C++ Library
We discovered that a lot of functions share a lot of code
To save our time, and to quickly generate wrappers for C/C++ Libraries to be used in Ring
We have this code generator
https://github.com/ring-lang/ring/blob/master/extensions/codegen/parsec.ring
The code generator is just a Ring program < 1200 lines of Ring code
The generator take as input a configuration file contains the C/C++ library information
like Functions Prototype, Classes and Methods, Constants, Enum, Structures and members , etc.
Then the generator will generate
*.C File for C libraries (to be able to use the library functions)
*.CPP File for C++ libraries (to be able to use C++ classes and methods)
*.Ring File (to be able to use C++ classes as Ring classes)
*.RH file (Constants)
To understand how the generator work check this extension for the Allegro game programming library
https://github.com/ring-lang/ring/tree/master/extensions/ringallegro
At first we have the configuration file
https://github.com/ring-lang/ring/blob/master/extensions/ringallegro/allegro.cf
To write this file, i just used the Allegro documentation + the Ring code generator rules
Then after executing the generator using this batch file
https://github.com/ring-lang/ring/blob/master/extensions/ringallegro/gencode.bat
or using this script
https://github.com/ring-lang/ring/blob/master/extensions/ringallegro/gencode.sh
I get the generated source code file
https://github.com/ring-lang/ring/blob/master/extensions/ringallegro/ring_allegro.c
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The generated source code file (ring_allegro.c) is around 12,000 Lines of code (12 KLOC)
While the configuration file is less than 1 KLOC
To build the library (create the DLL files)
https://github.com/ring-lang/ring/blob/master/extensions/ringallegro/buildvc.bat
Also you can check this extension for the LibSDL Library
https://github.com/ring-lang/ring/tree/master/extensions/ringsdl
After this know you should know about
1 - Writing the configuration file
2 - Using the Code Generator
3 - Building your library/extension
4 - Using your library/extension from Ring code
Let us move now to you question about Qt
We have RingQt which is just an extension to ring (ringqt.dll)
You don’t need to modify Ring.
1. You just need to modify RingQt
2. Or extend Ring with another extension based on Qt (but the same Qt version)
For the first option see the RingQt extension
https://github.com/ring-lang/ring/tree/master/extensions/ringqt
Configuration file
https://github.com/ring-lang/ring/blob/master/extensions/ringqt/qt.cf
To generate the source code
https://github.com/ring-lang/ring/blob/master/extensions/ringqt/gencode.bat
https://github.com/ring-lang/ring/blob/master/extensions/ringqt/gencode.sh
https://github.com/ring-lang/ring/blob/master/extensions/ringqt/gencodeandroid.bat
To build the DLL/so/Dylib files
https://github.com/ring-lang/ring/blob/master/extensions/ringqt/buildmingw32.bat
https://github.com/ring-lang/ring/blob/master/extensions/ringqt/buildgcc.sh
https://github.com/ring-lang/ring/blob/master/extensions/ringqt/buildclang.sh
Study RingQt
Learn about the options that you have
1. wrapping a Qt class directly
2. Creating a new class then wrapping your new class
For the second option (in the previous two points or in the two points before that)
You will create new classes in C++ code
Then you merge these classes to RingQt or provide special DLL for them (your decision)
If your work is general (will help others) just put it to RingQt.
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if your work is special (to specific application) just put it in another extension.
71.49 How to add Combobox and other elements to the cells of a
QTableWidget?
Check the next code
Load "guilib.ring"
New qApp
{
win1 = new qMainWindow() {
setGeometry(100,100,1100,370)
setwindowtitle("Using QTableWidget")
Table1 = new qTableWidget(win1) {
setrowcount(10) setcolumncount(10)
setGeometry(0,0,800,400)
setselectionbehavior(QAbstractItemView_SelectRows)
for x = 1 to 10
for y = 1 to 10
item1 = new qtablewidgetitem("R"+X+"C"+Y)
setitem(x-1,y-1, item1)
next
next
cmb = new QComboBox(Table1) {
alist = ["one","two","three","four","five"]
for x in aList additem(x,0) next
}
setCellWidget(5, 5, cmb)
}
setcentralwidget(table1)
show()
}
exec()
}
71.50 How to perform some manipulations on selected cells in
QTableWidget?
Check the next sample
Load "guilib.ring"
New qApp {
win1 = new qMainWindow() {
setGeometry(100,100,800,600)
setwindowtitle("Using QTableWidget")
Table1 = new qTableWidget(win1) {
setrowcount(10) setcolumncount(10)
setGeometry(10,10,400,400)
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for x = 1 to 10
for y = 1 to 10
item1 = new qtablewidgetitem("10")
setitem(x-1,y-1,item1)
next
next
}
btn1 = new qPushButton(win1) {
setText("Increase")
setGeometry(510,10,100,30)
setClickEvent("pClick()")
}
show()
}
exec()
}
func pClick
for nRow = 0 to Table1.rowcount() - 1
for nCol = 0 to Table1.columncount() - 1
Table1.item(nRow,nCol) {
if isSelected()
setText( "" + ( 10 + text()) )
ok
}
next
next
71.50. How to perform some manipulations on selected cells in QTableWidget? 840

24. CHAPTER
SEVENTYTWO
LANGUAGE REFERENCE
In this chapter we will learn about
• Language keywords
• Language Functions
• Compiler Errors
• Runtime Errors
• Language Grammar
• Virtual Machine (VM) Instructions
72.1 Language Keywords
Keywords Count : 46
• again
• and
• but
• bye
• call
• case
• catch
• changeringkeyword
• changeringoperator
• class
• def
• do
• done
• else
• elseif
• end
• exit
841

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• for
• from
• func
• get
• give
• if
• import
• in
• load
• loadsyntax
• loop
• new
• next
• not
• off
• ok
• on
• or
• other
• package
• private
• put
• return
• see
• step
• switch
• to
• try
• while
72.2 Language Functions
Functions Count : 233
acos() add() addattribute() adddays() addmethod() ascii()
asin() assert()
atan() atan2() attributes() binarysearch() callgc() ceil()
cfunctions() char()
chdir() classes() classname() clearerr() clock() clockspersecond()
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closelib() copy()
cos() cosh() currentdir() date() dec() decimals() decrypt() del()
diffdays() dir() download() encrypt() eval() exefilename()
exefolder() exp()
fabs() fclose() feof() ferror() fexists() fflush() fgetc() fgetpos()
fgets() filename() find() floor() fopen() fputc() fputs() fread()
freopen() fseek() fsetpos() ftell() functions() fwrite()
int2bytes() float2bytes() double2bytes()
bytes2int() bytes2float() bytes2double()
getattribute() getchar()
globals() hex() hex2str() input() insert() intvalue() isalnum() isalpha()
isandroid() isattribute() iscfunction() isclass() iscntrl()
isdigit() isfreebsd() isfunction()
isglobal() isgraph() islinux() islist() islocal()
islower() ismacosx() ismethod()
ismsdos() isnull() isnumber() isobject() ispackage()
ispackageclass() isprint() isprivateattribute()
isprivatemethod() ispunct() isspace() isstring()
isunix() isupper() iswindows() iswindows64()
isxdigit() left() len() lines() list() list2str() loadlib() locals()
log() log10() lower() max() md5() mergemethods() methods() min()
murmur3hash() mysql_autocommit() mysql_close()
mysql_columns() mysql_commit() mysql_connect() mysql_error()
mysql_escape_string()
mysql_info() mysql_init() mysql_insert_id() mysql_next_result()
mysql_query() mysql_result() mysql_result2() mysql_rollback()
nullpointer() number() object2pointer() objectid()
odbc_autocommit() odbc_close() odbc_colcount() odbc_columns()
odbc_commit() odbc_connect() odbc_datasources()
odbc_disconnect() odbc_drivers() odbc_execute() odbc_fetch() odbc_getdata()
odbc_init() odbc_rollback() odbc_tables() packageclasses() packagename()
packages() perror() pointer2object() pow()
prevfilename() ptrcmp() raise() randbytes() random()
read() remove() rename()
reverse() rewind() right()
ring_state_init() ring_state_runcode() ring_state_delete()
ring_state_runfile() ring_state_findvar() ring_state_newvar()
ring_state_runobjectfile() ring_state_main()
ringvm_calllist() ringvm_cfunctionslist() ringvm_classeslist()
ringvm_fileslist() ringvm_functionslist()
ringvm_memorylist() ringvm_packageslist() sendemail()
setattribute() sha1() sha224() sha256() sha384()
sha512() sin() sinh() sort() space() sqlite_close()
sqlite_errmsg() sqlite_execute()
sqlite_init() sqlite_open() sqrt() str2hex() str2list()
strcmp() string() substr() swap()
sysget() system() tan() tanh() tempfile() tempname() time() timelist()
trim() type() ungetc() unsigned() upper() varptr() version() windowsnl()
72.3 Compiler Errors
• Error (C1) : Error in parameters list, expected identifier
• Error (C2) : Error in class name
• Error (C3) : Unclosed control strucutre, ‘ok’ is missing
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• Error (C4) : Unclosed control strucutre, ‘end’ is missing
• Error (C5) : Unclosed control strucutre, next is missing
• Error (C6) : Error in function name
• Error (C7) : Error in list items
• Error (C8) : Parentheses ‘)’ is missing
• Error (C9) : Brackets ‘]’ is missing
• Error (C10) : Error in parent class name
• Error (C11) : Error in expression operator
• Error (C12) :No class definition
• Error (C13) : Error in variable name
• Error (C14) : Try/Catch miss the Catch keyword!
• Error (C15) : Try/Catch miss the Done keyword!
• Error (C16) : Error in Switch statement expression!
• Error (C17) : Switch statement without OFF
• Error (C18) : Missing closing brace for the block opened!
• Error (C19) : Numeric Overflow!
• Error (C20) : Error in package name
• Error (C21) : Unclosed control strucutre, ‘again’ is missing
• Error (C22) : Function redefinition, function is already defined!
• Error (C23) : Using ‘(‘ after number!
• Error (C24) : The parent class name is identical to the subclass name
• Error (C25) : Trying to access the self reference after the object name”
72.4 Runtime Errors
• Error (R1) : Cann’t divide by zero !
• Error (R2) : Array Access (Index out of range) !
• Error (R3) : Calling Function without definition !
• Error (R4) : Stack Overflow !
• Error (R5) : Can’t access the list item, Object is not list !
• Error (R6) : Variable is required
• Error (R7) : Can’t assign to a string letter more than one character
• Error (R8) : Variable is not a string
• Error (R9) : Using exit command outside loops
• Error (R10) : Using exit command with number outside the range
• Error (R11) : error in class name, class not found!
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• Error (R12) : error in property name, property not found!
• Error (R13) : Object is required
• Error (R14) : Calling Method without definition !
• Error (R15) : error in parent class name, class not found!
• Error (R16) : Using braces to access unknown object !
• Error (R17) : error, using ‘Super’ without parent class!
• Error (R18) : Numeric Overflow!
• Error (R19) : Calling function with less number of parameters!
• Error (R20) : Calling function with extra number of parameters!
• Error (R21) : Using operator with values of incorrect type
• Error (R22) : Using loop command outside loops
• Error (R23) : Using loop command with number outside the range
• Error (R24) : Using uninitialized variable
• Error (R25) : Error in package name, Package not found!
• Error (R26) : Calling private method from outside the class
• Error (R27) : Using private attribute from outside the class
• Error (R28) : Using bad data type as step value
• Error (R29) : Using bad data type in for loop
• Error (R30) : parent class name is identical to child class name
• Error (R31) : Trying to destory the object using the self reference
• Error (R32) : The CALL command expect a variable contains string!
• Error (R33) : Bad decimals number (correct range >= 0 and <=14) !
• Error (R34) : Variable is required for the assignment operation
• Error (R35) : Can’t create/open the file!
• Error (R36) : The column number is not correct! It’s greater than the number of columns in the list
72.5 Language Grammar
Program —> {statement}
Statement —> ‘package’ <Identifier> { ‘.’ <Identifier> }
Statement —> ‘class’ <Identifier> [ ‘from’|’:’|’<’ <Identifier> ]
Statement —> ‘func’|’def’ <Identifier> [ParaList]
Statement —> ‘import’ <Identifier> { ‘.’ <Identifier> }
Statement —> ‘private’
Statement —> ‘load’ <Literal>
Statement —> ‘loadsyntax’ <Literal>
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Statement —> ‘changeringkeyword’ <OldKeyword> <NewKeyword>
Statement —> ‘changeringoperator’ <OldOperator> <NewOperator>
Statement —> ‘see’|’put’ <Expr>
Statement —> ‘give’|’get’ <Identifier>
Statement —> ‘if’ <Expr> [’{‘] {statement} [ {‘but’|’elseif’ <Expr> {Statement} } ] [’else’ {Statement} ]
‘ok’|’end’|’}’
Statement —> ‘Switch’ <Expr> [’{‘] { ‘on’|’case’ <Expr> {statement} } [’other’ {Statement} ] ‘off’|’end’|’}’
Statement —> ‘for’ <Identifier> ‘=’ <Expr> ‘to’ <Expr> [ ‘step’ <Expr> ] [’{‘] {Statement} ‘next’|’end’|’}’
Statement —> ‘for’ <Identifier> ‘in’ <Expr> [ ‘step’ <Expr> ] [’{‘] {statement} ‘next’|’end’|’}’
Statement —> ‘while’ <Expr> [’{‘] {statement} ‘end’|’}’
Statement —> ‘do’ {statement} ‘again’ <Expr>
Statement —> ‘try’ {statement} [’{‘] ‘catch’ {statement} ‘done’|’end’|’}’
Statement —> ‘return’ <Expr>
Statement —> ‘bye’
Statement —> ‘exit’
Statement —> ‘loop’
Statement —> <Expr>
Statement —> epslion
ParaList —> epslion
ParaList —> [’(‘] <Identifier> [{ ‘,’ <Identifier> }] [’)’]
Expr —> <LogicNot> [{ ‘and’|’or’ <LogicNot> }]
LogicNot –> [’not’] <EqualOrNot>
EqualOrNot –> [ ‘=’|’!=’ ] <Compare>
Compare —> <BitOrXor> [ { ‘<’ | ‘>’ | ‘<=’ | ‘>=’ <BitOrXor> } ]
BitOrXor —> <BitAnd> [ { ‘|’ | ‘^’ <BitAnd> } ]
BitAnd —> <BitShift> [ { ‘&’ <BitShift> } ]
BitShift —> <Arithmetic> [ { ‘<<’ | ‘>>’ <Arithmetic> } ]
Arithmetic —> <Term> [ { ‘+’ | ‘-‘ <Term> } ]
Term —> <Range> [ { ‘*’ | ‘/’ | ‘%’ <Range> } ]
Range —> <Factor> [ ‘:’ <Factor> ]
Factor —> <Identifier> [ {Mixer} ] [ ‘=’ <Expr> ]
Factor —> <Number>
Factor —> <Literal>
Factor —> ‘:’ <Identifier>
Factor —> ‘-‘ <Expr>
Factor —> ‘(‘ <Expr> ‘)’
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Factor —> <List>
Factor —> ‘new’ <Identifier>
Factor —> <AnonymousFunction>
Factor —> ‘call’ <identifier> { ‘.’ <Identifier> } ‘(‘ <Parameters> ‘)’
List —> ‘[’ [ <Expr> { ‘,’ <Expr> } ] ‘]’
Mixer —> { ‘.’ <Identifier> }
Mixer —> ‘[’ <Expr> ‘]’
Mixer —> ‘(‘ [ <Expr> [ { ‘,’ <Expr> }] ] ‘)’
Mixer —> ‘{‘ {Statement} ‘}’
AnonymousFunction —> ‘func’|’def’| [<ParaList>] ‘{‘ {Statement} ‘}’
72.6 Virtual Machine (VM) Instructions
Definitions :-
• VM : Virtual Machine
• Stack : VM Stack
• IR : Instruction Register
• PC : Program Counter
• VP : Variable Pointer
• Stack[nSize] : Last Item in the Stack (Last In - First Out)
• VV : Variable Value (We have a Pointer to a variable, And we access this variable value)
(Stack and Variables)
72.6. Virtual Machine (VM) Instructions 847