The Ring programming language version 1.5.2 book - Part 176 of 181

1. Ring Documentation, Release 1.5.2
Columns Count : 3
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”.
95.46 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
95.46. Can I connect to dbase/harbour database? 1725

2. Ring Documentation, Release 1.5.2
odbc_connect(pODBC,"Driver={Microsoft Visual FoxPro Driver};"+
"SourceType=DBC;SourceDB=C:PWCT19ssbuildPWCTDATACH1Datamydata.dbc;")
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)
95.47 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).
95.48 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
95.47. Why setClickEvent() doesn’t see the object methods directly? 1726

3. Ring Documentation, Release 1.5.2
see "message from the test function!" + nl
class test
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
95.49 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
95.50 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)
{
95.49. Can Ring work on Windows XP? 1727

4. Ring Documentation, Release 1.5.2
printf("Message from dlfunc");
}
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
95.50. How to extend RingQt and add more classes? 1728

5. Ring Documentation, Release 1.5.2
I get the generated source code file
https://github.com/ring-lang/ring/blob/master/extensions/ringallegro/ring_allegro.c
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
95.50. How to extend RingQt and add more classes? 1729

6. Ring Documentation, Release 1.5.2
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.
if your work is special (to specific application) just put it in another extension.
95.51 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()
}
95.52 How to perform some manipulations on selected cells in
QTableWidget?
Check the next sample
Load "guilib.ring"
New qApp {
95.51. How to add Combobox and other elements to the cells of a QTableWidget? 1730

7. Ring Documentation, Release 1.5.2
win1 = new qMainWindow() {
setGeometry(100,100,800,600)
setwindowtitle("Using QTableWidget")
Table1 = new qTableWidget(win1) {
setrowcount(10) setcolumncount(10)
setGeometry(10,10,400,400)
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
95.52. How to perform some manipulations on selected cells in QTableWidget? 1731

8. CHAPTER
NINETYSIX
LANGUAGE REFERENCE
In this chapter we will learn about
• Language keywords
• Language Functions
• Compiler Errors
• Runtime Errors
• Environment Errors
• Language Grammar
• Virtual Machine (VM) Instructions
96.1 Language Keywords
Keywords Count : 49
• again
• and
• but
• bye
• call
• case
• catch
• changeringkeyword
• changeringoperator
• class
• def
• do
• done
• else
• elseif
• end
1732

9. Ring Documentation, Release 1.5.2
• exit
• 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
• endfunc
• endclass
• endpackage
96.1. Language Keywords 1733

10. Ring Documentation, Release 1.5.2
96.2 Language Functions
Functions Count : 197
len() add() del() sysget() clock() lower()
upper() input() ascii() char() date() time()
filename() getchar() system() random() timelist() adddays()
diffdays() version() clockspersecond() prevfilename() swap() shutdown()
isstring() isnumber() islist() type() isnull() isobject()
hex() dec() number() string() str2hex() hex2str()
str2list() list2str() left() right() trim() copy()
substr() lines() strcmp() eval() raise() assert()
isalnum() isalpha() iscntrl() isdigit() isgraph() islower()
isprint() ispunct() isspace() isupper() isxdigit() locals()
globals() functions() cfunctions() islocal() isglobal() isfunction()
iscfunction() packages() ispackage() classes() isclass() packageclasses()
ispackageclass() classname() objectid() attributes() methods() isattribute()
ismethod() isprivateattribute() isprivatemethod()
addattribute() addmethod() getattribute()
setattribute() mergemethods() packagename() ringvm_fileslist()
ringvm_calllist() ringvm_memorylist()
ringvm_functionslist() ringvm_classeslist() ringvm_packageslist()
ringvm_cfunctionslist() ringvm_settrace() ringvm_tracedata()
ringvm_traceevent() ringvm_tracefunc() ringvm_scopescount()
ringvm_evalinscope() ringvm_passerror() ringvm_hideerrormsg()
ringvm_callfunc() list() find() min() max() insert()
sort() reverse() binarysearch() sin() cos() tan()
asin() acos() atan() atan2() sinh() cosh()
tanh() exp() log() log10() ceil() floor()
fabs() pow() sqrt() unsigned() decimals() murmur3hash()
fopen() fclose() fflush() freopen() tempfile() tempname()
fseek() ftell() rewind() fgetpos() fsetpos() clearerr()
feof() ferror() perror() rename() remove() fgetc()
fgets() fputc() fputs() ungetc() fread() fwrite()
dir() read() write() fexists() int2bytes() float2bytes()
double2bytes() bytes2int() bytes2float()
bytes2double() ismsdos() iswindows()
iswindows64() isunix() ismacosx() islinux() isfreebsd() isandroid()
windowsnl() currentdir() exefilename() chdir() exefolder() loadlib()
closelib() callgc() varptr() intvalue() object2pointer() pointer2object()
nullpointer() space() ptrcmp() ring_state_init()
ring_state_runcode() ring_state_delete()
ring_state_runfile() ring_state_findvar() ring_state_newvar()
ring_state_runobjectfile()
96.3 Compiler Errors
• Error (C1) : Error in parameters list, expected identifier
• Error (C2) : Error in class name
• Error (C3) : Unclosed control strucutre, ‘ok’ is missing
• Error (C4) : Unclosed control strucutre, ‘end’ is missing
• Error (C5) : Unclosed control strucutre, next is missing
• Error (C6) : Error in function name
96.2. Language Functions 1734