The Ring programming language version 1.4 book - Part 10 of 30

Ring Documentation, Release 1.4
Ring
***Ring*** programming language
******Ring****** programming language
FirstSecond
FirstFirstFirst
FirstFirstFirst
one
two
three
Hello
How are you?
40.3 List Class
Parent Class : StdBase Class
Methods:
Method Description/Output
Init(String|List)
Add(Value) Add item to the list
Delete(nIndex) Delete item from the list
Item(nIndex) Get item from the list
First() Get the ﬁrst item in the list
Last() Get the last item in the list
Set(nIndex,Value) Set item value
FindInColumn(nCol,Value) Find item in a column
Sort() Sort items - return new list
Reverse() Reverse items - return new list
Insert(nIndex,Value) Inset Item after nIndex
example:
Load "stdlib.ring"
oList = new list ( [1,2,3] )
oList.Add(4)
oList.print()
see oList.item(1) + nl
oList.delete(4)
oList.print()
see oList.first() + nl
see oList.last() + nl
oList { set(1,"one") set(2,"two") set(3,"three") print() }
see oList.find("two") + nl
oList.sort().print()
oList.reverse().print()
oList.insert(2,"nice")
oList.print()
oList = new list ( [ [1,"one"],[2,"two"],[3,"three"] ] )
see copy("*",10) + nl
oList.print()
see "Search two : " + oList.findincolumn(2,"two") + nl
see "Search 1 : " + oList.findincolumn(1,1) + nl
oList = new list ( [ "Egypt" , "USA" , "KSA" ] )
for x in oList
40.3. List Class 248

see x + nl
next
oList = new list ( [1,2,3,4] )
oList + [5,6,7]
oList.print()
oList = new list ( ["one","two"] )
oList2 = new list ( ["three","four"] )
oList + oList2
oList.print()
output:
1
2
3
4
1
1
2
3
1
3
one
two
three
2
one
three
two
three
two
one
one
two
nice
three
**********
1
one
2
two
3
three
Search two : 2
Search 1 : 1
Egypt
USA
KSA
1
2
3
4
5
6
7
one
two
three
40.3. List Class 249

four
40.4 Stack Class
Parent Class : List Class
Methods:
Init(String|Number|List)
Push(Value) Push item to the stack
Pop() Pop item from the stack
Print() Print the stack items
example:
Load "stdlib.ring"
oStack = new Stack
oStack.push(1)
oStack.push(2)
oStack.push(3)
see oStack.pop() + nl
oStack.push(4)
oStack { push("one") push("two") push("three") }
oStack.print()
output:
3
2
1
4
three
two
one
40.5 Queue Class
Methods:
Init(String|Number|List)
Remove() Remove item from the Queue.
example:
Load "stdlib.ring"
oQueue = new Queue
oQueue.add(1)
40.4. Stack Class 250

oQueue.add(2)
oQueue.add(3)
see oQueue.remove() + nl
oQueue.add(4)
oQueue { add("one") add("two") add("three") }
oQueue.print()
output:
1
2
3
4
one
two
three
40.6 HashTable Class
Methods:
Init(List)
Add(cKey,Value) Add item to the HashTable
Set(cKey,Value) Set item value using the Key
GetValue(cKey) Get item value using the Key
Contains(cKey) Check if the HashTable contains item using the Key
Index(cKey) Get the item index using the Key
example:
Load "stdlib.ring"
ohashtable = new hashtable
See "Test the hashtable Class Methods" + nl
ohashtable {
Add("Egypt","Cairo")
Add("KSA","Riyadh")
see self["Egypt"] + nl
see self["KSA"] + nl
see contains("Egypt") + nl
see contains("USA") + nl
see index("KSA") + NL
print()
delete(index("KSA"))
print()
}
output:
40.6. HashTable Class 251

Test the hashtable Class Methods
Cairo
Riyadh
1
0
2
Egypt
Cairo
KSA
Riyadh
************************************************************
Egypt
Cairo
40.7 Tree Class
Data:
Attribute Description
Data Node Value
Children Children List
Methods:
set(value) Set the node value.
value() Get the node value.
Add(value) Add new child.
parent() Get the parent node.
print() Print the tree nodes.
example:
Load "stdlib.ring"
otree = new tree
See "Test the tree Class Methods" + nl
otree {
set("The first step") # set the root node value
see value() + nl
Add("one")
Add("two")
Add("three") {
Add("3.1")
Add("3.2")
Add("3.3")
see children
}
see children
oTree.children[2] {
Add("2.1") Add("2.2") Add("2.3") {
Add("2.3.1") Add("2.3.2") Add("test")
}
}
oTree.children[2].children[3].children[3].set("2.3.3")
}
40.7. Tree Class 252

oTree.print()
output:
Test the tree Class Methods
The first step
data: 3.1
parent: List...
children: List...
data: 3.2
parent: List...
children: List...
data: 3.3
parent: List...
children: List...
data: one
parent: List...
children: List...
data: two
parent: List...
children: List...
data: three
parent: List...
children: List...
************************************************************
one
two
2.1
2.2
2.3
2.3.1
2.3.2
2.3.3
three
3.1
3.2
3.3
40.8 Math Class
Methods:
40.8. Math Class 253

Method Description
sin(x) Returns the sine of an angle of x radians
cos(x) Returns the cosine of an angle of x radians
tan(x) Returns the tangent of an angle of x radians
asin(x) Returns the principal value of the arc sine of x, expressed in radians
acos(x) Returns the principal value of the arc cosine of x, expressed in radians
atan(x) Returns the principal value of the arc tangent of x, expressed in radians
atan2(y,x) Returns the principal arc tangent of y/x, in the interval [-pi,+pi] radians
sinh(x) Returns the hyperbolic sine of x radians
cosh(x) Returns the hyperbolic cosine of x radians
tanh(x) Returns the hyperbolic tangent of x radians
exp(x) Returns the value of e raised to the xth power
log(x) Returns the natural logarithm of x
log10(x) Returns the common logarithm (base-10 logarithm) of x
ceil(x) Returns the smallest integer value greater than or equal to x
ﬂoor(x) Returns the largest integer value less than or equal to x
fabs(x) Returns the absolute value of x.
pow(x,y) Returns x raised to the power of y
sqrt(x) Returns the square root of x
random(x) Returns a random number in the range [0,x]
unsigned(n,n,c) Perform operation using unsigned numbers
decimals(n) Determine the decimals digits after the point in ﬂoat/double numbers
example:
Load "stdlib.ring"
oMath = new Math
See "Test the Math Class Methods" + nl
See "Sin(0) = " + oMath.sin(0) + nl
See "Sin(90) radians = " + oMath.sin(90) + nl
See "Sin(90) degree = " + oMath.sin(90*3.14/180) + nl
See "Cos(0) = " + oMath.cos(0) + nl
See "Cos(90) radians = " + oMath.cos(90) + nl
See "Cos(90) degree = " +oMath. cos(90*3.14/180) + nl
See "Tan(0) = " + oMath.tan(0) + nl
See "Tan(90) radians = " + oMath.tan(90) + nl
See "Tan(90) degree = " + oMath.tan(90*3.14/180) + nl
See "asin(0) = " + oMath.asin(0) + nl
See "acos(0) = " + oMath.acos(0) + nl
See "atan(0) = " + oMath.atan(0) + nl
See "atan2(1,1) = " +oMath. atan2(1,1) + nl
See "sinh(0) = " + oMath.sinh(0) + nl
See "sinh(1) = " + oMath.sinh(1) + nl
See "cosh(0) = " + oMath.cosh(0) + nl
See "cosh(1) = " + oMath.cosh(1) + nl
See "tanh(0) = " + oMath.tanh(0) + nl
See "tanh(1) = " + oMath.tanh(1) + nl
See "exp(0) = " + oMath.exp(0) + nl
See "exp(1) = " + oMath.exp(1) + nl
See "log(1) = " + oMath.log(1) + nl

See "log(2) = " + oMath.log(2) + nl
See "log10(1) = " + oMath.log10(1) + nl
See "Ceil(1.12) = " + oMath.Ceil(1.12) + nl
See "Ceil(1.72) = " + oMath.Ceil(1.72) + nl
See "Floor(1.12) = " + oMath.floor(1.12) + nl
See "Floor(1.72) = " + oMath.floor(1.72) + nl
See "fabs(1.12) = " + oMath.fabs(1.12) + nl
See "fabs(1.72) = " + oMath.fabs(1.72) + nl
See "pow(2,3) = " + oMath.pow(2,3) + nl
see "sqrt(16) = " + oMath.sqrt(16) + nl
for x = 1 to 20
see "Random number Max (100) : " + oMath.random(100) + nl
next
x = 1.1234567890123
for d = 0 to 14
oMath.decimals(d)
see x + nl
next
cKey = "hello"
h = 0
for x in cKey
h = oMath.unsigned(h,ascii(x),"+")
h = oMath.unsigned(h,oMath.unsigned(h,10,"<<"),"+")
r = oMath.unsigned(h,6,">>")
h = oMath.unsigned(h, r,"^")
next
h = oMath.unsigned(h,oMath.unsigned(h,11,">>"),"^")
see "Hash : " + h
output:
Test the Math Class Methods
Sin(0) = 0
Sin(90) radians = 0.89
Sin(90) degree = 1.00
Cos(0) = 1
Cos(90) radians = -0.45
Cos(90) degree = 0.00
Tan(0) = 0
Tan(90) radians = -2.00
Tan(90) degree = 1255.77
asin(0) = 0
acos(0) = 1.57
atan(0) = 0
atan2(1,1) = 0.79

sinh(0) = 0
sinh(1) = 1.18
cosh(0) = 1
cosh(1) = 1.54
tanh(0) = 0
tanh(1) = 0.76
exp(0) = 1
exp(1) = 2.72
log(1) = 0
log(2) = 0.69
log10(1) = 0
log10(2) = 0.30
log10(10) = 1
Ceil(1.12) = 2
Ceil(1.72) = 2
Floor(1.12) = 1
Floor(1.72) = 1
fabs(1.12) = 1.12
fabs(1.72) = 1.72
pow(2,3) = 8
sqrt(16) = 4
Random number Max (100) : 87
1
1.1
1.12
1.123
1.1235
1.12346
1.123457
1.1234568
1.12345679
1.123456789
1.1234567890
1.12345678901
1.123456789012
1.1234567890123
1.12345678901230
Hash : 3372029979.00000000000000

40.9 DateTime Class
Methods:
clock() The number of clock ticks from program start.
time() Get the system time.
date() Get the date.
timelist() List contains the date and the time information.
adddays(cDate,nDays) Return Date from cDate and after nDays
diffdays(cDate1,cDate2) Return the Number of days (cDate1 - cDate2)
example:
Load "stdlib.ring"
oDateTime = new datetime
See "Test the datetime Class Methods" + nl
See "Calculate performance" + nl
t1 = oDateTime.clock()
for x = 1 to 1000000 next
see oDateTime.clock() - t1 + nl
See "Time : " + oDateTime.time() + nl
See "Date : " + oDateTime.date() + nl
See oDateTime.TimeList()
See "Month Name : " + oDateTime.TimeList()[4]
cDate = oDateTime.date()
see cDate + nl
cDate = oDateTime.adddays(cDate,10)
see cDate + nl
cDate1 = oDateTime.date()
see cDate1 + nl
cDate2 = oDateTime.adddays(cDate1,10)
see cDate2 + nl
see "DiffDays = " + oDateTime.diffdays(cDate1,cDate2) + nl
see "DiffDays = " + oDateTime.diffdays(cDate2,cDate1) + nl
output:
Test the datetime Class Methods
Calculate performance
85
Time : 02:53:35
Date : 31/08/2016
Wed
Wednesday
Aug
August
08/31/16 02:53:35
31
40.9. DateTime Class 257

02
02
244
08
53
AM
35
35
3
08/31/16
02:53:35
16
2016
Arab Standard Time
%
Month Name : August31/08/2016
10/09/2016
31/08/2016
10/09/2016
DiffDays = -10
DiffDays = 10
40.10 File Class
Methods:
40.10. File Class 258

read(cFileName) Read the file content
write(cFileName,cStr) Write string to file
dir(cFolderPath) Get the folder contents (files & sub folders)
rename(cOld,cNew) Rename files using the Rename() function
remove(cFileName) Delete a file using the Remove() function
open(cFileName,cMode) Open a file using the Fopen() function
close() Close file
flush() Flushes the output buffer of a stream
reopen(cFileName,cMode) Open another file using the same file handle
tempfile() Creates a temp. file (binary).
seek(noffset,nwhence) Set the file position of the stream
tell() Know the current file position of a stream
rewind() Set the file position to the beginning of the file
getpos() Get handle to the current file position
setpos(poshandle) Set the current file position
clearerr() Clear the EOF error and the error indicators of a stream
eof() Test the end-of-file indicator
error() Test the error indicator
perror(cErrorMessage) Print error message to the stderr
getc() Get the next character from the stream
gets(nsize) Read new line from the stream
putc(cchar) Write a character to the stream
puts(cStr) Write a string to the stream
ungetc(cchar) Push a character to the stream
fread(nsize) Read data from a stream
fwrite(cString) Write data to a stream
exists(cFileName) Check if a file exists
example:
Load "stdlib.ring"
ofile = new file
See "Test the file Class Methods" + nl
see ofile.read(filename())
see nl
ofile.open(filename(),"r")
see ofile.gets(100) + nl
ofile.close()
40.11 System Class
Methods:
40.11. System Class 259

system() Execute system commands
sysget() Get environment variables
ismsdos() Check if the operating system is MSDOS or not
iswindows() Check if the operating system is Windows or not
iswindows64() Check if the operating system is Windows 64bit or not
isunix() Check if the operating system is Unix or not
ismacosx() Check if the operating system is Mac OS X or not
islinux() Check if the operating system is Linux or not
isfreebsd() Check if the operating system is FreeBSD or not
isandroid() Check if the operating system is Android or not
windowsnl() Get the windows new line string
sysargv() Get the command line arguments passed to the ring script
ﬁlename() Get the active source ﬁle
example:
Load "stdlib.ring"
oSystem = new System
See "Test the System Class Methods" + nl
oSystem.system("dir")
see oSystem.sysget("path") + nl
see oSystem.ismsdos() + nl
see oSystem.iswindows() + nl
see oSystem.iswindows64() + nl
see oSystem.isunix() + nl
see oSystem.ismacosx() + nl
see oSystem.islinux() + nl
see oSystem.isfreebsd() + nl
see oSystem.isandroid() + nl
see oSystem.windowsnl() + nl
see oSystem.sysargv() + nl
see oSystem.filename() + nl
40.12 Debug Class
Methods:
eval(cCode) Execute code during the runtime from string.
raise(cError) Raise an exception.
assert(cCondition) Test condition before executing the code.
example:
Load "stdlib.ring"
oDebug = new Debug
See "Test the Debug Class Methods" + nl
oDebug.eval("see 'Hello'+nl")
try
x = 10
oDebug.assert(x=11)
40.12. Debug Class 260

catch see "assert" + nl done
raise("Error!")
40.13 DataType Class
Methods:
isstring(vValue) We can know if the value is a string or not.
isnumber(vValue) We can know if the value is a number or not.
islist(vValue) We can know if the value is a list or not.
type(vValue) Know the type of a value
isnull(vValue) Check the value to know if it’s null or not.
isalnum(vValue) 1 if the value is digit/letter or 0 if not
isalpha(vValue) 1 if the value is a letter or 0 if not
iscntrl(vValue) 1 if the value is a control character (no printing position)
isdigit(vValue) 1 if the value is a digit or 0 if not
isgraph(vValue) 1 if the value can be printed (Except space) or 0 if not
islower(vValue) 1 if the value is lowercase letter or 0 if not
isprint(vValue) 1 if the value occupies a printing position or 0 if not
ispunct(vValue) 1 if the value is a punctuation character or 0 if not
isspace(vValue) 1 if the value is a white-space or 0 if not
isupper(vValue) 1 if the value is an uppercase alphabetic letter or 0 if not
isxdigit(vValue) 1 if the value is a hexdecimal digit character or 0 if not
example:
Load "stdlib.ring"
oDataType = new DataType
See "Test the DataType Class Methods" + nl
see oDataType.isstring("test") + nl
see oDataType.isnumber(1) + nl
see oDataType.islist(1:3) + nl
see oDataType.type("test") + nl
see oDataType.isnull(null) + nl
see oDataType.isalnum("Hello") + nl + # print 1
oDataType.isalnum("123456") + nl + # print 1
oDataType.isalnum("ABCabc123") + nl + # print 1
oDataType.isalnum("How are you") + nl # print 0 because of spaces
see oDataType.isalpha("Hello") + nl + # print 1
oDataType.isalpha("123456") + nl + # print 0
oDataType.isalpha("ABCabc123") + nl + # print 0
oDataType.isalpha("How are you") + nl # print 0
See oDataType.iscntrl("hello") + nl + # print 0
oDataType.iscntrl(nl) # print 1
see oDataType.isdigit("0123456789") + nl + # print 1
oDataType.isdigit("0123a") + nl
see oDataType.isgraph("abcdef") + nl + # print 1
oDataType.isgraph("abc def") + nl # print 0
see oDataType.islower("abcDEF") + nl + # print 0
oDataType.islower("ghi") + nl # print 1
see oDataType.isprint("Hello") + nl + # print 1
oDataType.isprint("Nice to see you") + nl + # print 1
oDataType.isprint(nl) + nl # print 0
40.13. DataType Class 261

see oDataType.isprint("Hello") + nl # print 1
see oDataType.isupper("welcome") + nl + # print 0
oDataType.isupper("WELCOME") + nl # print 1
see oDataType.isxdigit("0123456789abcdef") + nl + # print 1
oDataType.isxdigit("123z") # print 0
Output:
Test the DataType Class Methods
1
1
1
STRING
1
1
1
1
0
1
0
0
0
0
11
0
1
0
0
1
1
1
0
1
0
1
1
0
40.14 Conversion Class
Methods:
number(vValue) Convert strings to numbers.
string(vValue) Convert numbers to strings.
ascii(vValue) Get the ASCII code for a letter.
char(vValue) Convert the ASCII code to character.
hex(vValue) Convert decimal to hexadecimal.
dec(vValue) Convert hexadecimal to decimal.
str2hex(vValue) Convert string characters to hexadecimal characters.
hex2str(vValue) Convert hexadecimal characters to string.
example:
Load "stdlib.ring"
40.14. Conversion Class 262

oConversion = new conversion
See "Test the conversion Class Methods" + nl
See oConversion.number("3") + 5 + nl
See oConversion.string(3) + "5" + nl
See oConversion.Ascii("m") + nl
See oConversion.char(77) + nl
see oConversion.hex(162) + nl
see oConversion.dec("a2") + nl
cHex = oConversion.str2hex("Hello")
see cHex + nl
see oConversion.hex2str(cHex) + nl
Output:
Test the conversion Class Methods
8
35
109
M
a2
162
48656c6c6f
Hello
40.15 ODBC Class
Methods:
drivers() Get a list of ODBC drivers.
datasources() Get a list of ODBC data sources.
close() Free resources.
connect(cConString) Connect to the database.
disconnect() Close the connection.
execute(cSQL) Execute SQL Statements
colcount() Get columns count in the query result
fetch() Fetch a row from the query result
getdata(nCol) Get column value from the fetched row
tables() Get a list of tables inside the database
columns(cTableName) Get a list of columns inside the table
autocommit(lStatus) Enable or disable the auto commit feature
commit() Commit updates to the database
rollback() Rollback updates to the database
example:
Load "stdlib.ring"
oodbc = new odbc
See "Test the odbc Class Methods" + nl
oODBC {
see drivers()
see datasources()
See "Connect to database" + nl
see connect("DBQ=test.mdb;Driver={Microsoft Access Driver (*.mdb)}") + nl
See "Select data" + nl
40.15. ODBC Class 263

see execute("select * from person") + nl
nMax = colcount()
See "Columns Count : " + nMax + nl
while fetch()
See "Row data:" + nl
for x = 1 to nMax
see getdata(x) + " - "
next
end
See "Close database..." + nl
disconnect()
close()
}
40.16 MySQL Class
Methods:
info() Return string contains the MySQL Client version.
error() Get the error message from the MySQL Client.
connect(cServer,cUser,cPass,cDatabase) Connect to the MySQL database server.
close() Close the connection to the MySQL database.
query(cQuery) Execute SQL queries.
insert_id() Get the inserted row id.
result() Get the query result (data without column names).
next_result() Move to the next query result.
columns() Get a list of columns names.
result2() Get all of the column names then the query result in one list.
escape_string(cStr) Before storing binary data and special characters in the database.
autocommit(lStatus) Enable or disable the auto commit feature.
commit() Commit updates to the database.
rollback() Rollback updates to the database.
example:
Load "stdlib.ring"
omysql = new mysql
See "Test the MySQL Class Methods" + nl
omysql {
see info() + nl
connect("localhost", "root", "root","mahdb")
see "Execute Query" + nl
query("SELECT * FROM Employee")
see "Print Result" + nl
see result2()
see "Close database" + nl
close()
}
Output:
Test the MySQL Class Methods
5.5.30
40.16. MySQL Class 264

Execute Query
Print Result
Id
Name
Salary
1
Mahmoud
15000
2
Samir
16000
3
Fayed
17000
Close database
40.17 SQLite Class
Methods:
open(cDatabase) Open Database.
close() Close Database.
errormessage() Get Error Message.
execute(cSQL) Execute Query.
example:
Load "stdlib.ring"
osqlite = new sqlite
See "Test the sqlite Class Methods" + nl
osqlite {
open("test.db")
sql = "CREATE TABLE COMPANY(" +
"ID INT PRIMARY KEY NOT NULL," +
"NAME TEXT NOT NULL," +
"AGE INT NOT NULL," +
"ADDRESS CHAR(50)," +
"SALARY REAL );"
execute(sql)
sql = "INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) " +
"VALUES (1, 'Mahmoud', 29, 'Jeddah', 20000.00 ); " +
"INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY) " +
"VALUES (2, 'Ahmed', 27, 'Jeddah', 15000.00 ); " +
"INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY)" +
"VALUES (3, 'Mohammed', 31, 'Egypt', 20000.00 );" +
"INSERT INTO COMPANY (ID,NAME,AGE,ADDRESS,SALARY)" +
"VALUES (4, 'Ibrahim', 24, 'Egypt ', 65000.00 );"
execute(sql)
aResult = execute("select * from COMPANY")
for x in aResult
for t in x
40.17. SQLite Class 265

see t[2] + nl
next
next
for x in aResult
see x["name"] + nl
next
close()
}
Output:
Test the sqlite Class Methods
1
Mahmoud
29
Jeddah
20000.0
2
Ahmed
27
Jeddah
15000.0
3
Mohammed
31
Egypt
20000.0
4
Ibrahim
24
Egypt
65000.0
**************************************************
Mahmoud
Ahmed
Mohammed
Ibrahim
40.18 Security Class
Methods:
md5(cString) Calculate the MD5 hash.
sha1(cString) Calculate the SHA1 hash.
encrypt(cString,cKey,cIV) Cncrypts the data using the Blowﬁsh algorithm.
decrypt(cString,cKey,cIV) Decrypt the data encrypted using the Encrypt() method.
randbytes(nSize) Generate a string of pseudo-random bytes.
example:
40.18. Security Class 266

Load "stdlib.ring"
osecuirty = new secuirty
See "Test the secuirty Class Methods" + nl
oSecuirty {
see md5("hello") + nl +
sha1("hello") + nl + sha256("hello") + nl +
sha512("hello") + nl + sha384("hello") + nl +
sha256("hello") + nl
list = 0:15 cKey="" for x in list cKey += char(x) next
list = 1:8 cIV = "" for x in list cIV += char(x) next
cCipher = encrypt("hello",cKey,cIV)
see cCipher + nl + decrypt(cCipher,cKey,cIV) + nl
}
40.19 Internet Class
Methods:
• download(cURL)
• sendemail(cSMTPServer,cEmail,cPassword,cSender,cReceiver,cCC,cTitle,cContent)
example:
Load "stdlib.ring"
ointernet = new internet
See "Test the internet Class Methods" + nl
ointernet {
see download("www.ring-lang.sf.net")
}
40.19. Internet Class 267

CHAPTER
FORTYONE
DECLARATIVE PROGRAMMING USING NESTED STRUCTURES
In this chapter we are going to learn how to build declarative programming world using nested structures on the top of
object oriented.
We will learn about
• Creating Objects inside Lists
• Composition and Returning Objects and Lists by Reference
• Executing code after the end of object access
• Declarative Programming on the top of Object-Oriented
41.1 Creating Objects inside Lists
We can create objects inside lists during list deﬁnition. Also we can add objects to the list at any time using the Add()
function or the + operator.
Example:
alist = [new point, new point, new point] # create list contains three objects
alist + [1,2,3] # add another item to the list
see "Item 4 is a list contains 3 items" + nl
see alist[4]
add(alist , new point)
alist + new point
alist[5] { x = 100 y = 200 z = 300 }
alist[6] { x = 50 y = 150 z = 250 }
see "Object inside item 5" + nl
see alist[5]
see "Object inside item 6" + nl
see alist[6]
class point x y z
Output:
Item 4 is a list contains 3 items
1
2
268

3
Object inside item 5
x: 100.000000
y: 200.000000
z: 300.000000
Object inside item 6
x: 50.000000
y: 150.000000
z: 250.000000
41.2 Composition and Returning Objects and Lists by Reference
When we use composition and have object as one of the class attributes, when we return that object it will be returned
by reference.
if the called used the assignment operator, another copy of the object will be created.
The caller can avoid using the assignment operator and use the returned reference directly to access the object.
The same is done also if the attribute is a list (not object).
Note: Objects and Lists are treated using the same rules. When you pass them to function they are passed by
reference,
when you return them from functions they are returned by value except if it’s an object attribute where a return by
reference will be done.
Example:
o1 = new Container
myobj = o1.addobj() # the assignment will create another copy
myobj.x = 100
myobj.y = 200
myobj.z = 300
see o1.aobjs[1] # print the object inside the container
see myobj # print the copy
Class Container
aObjs = []
func addobj
aobjs + new point
return aobjs[len(aobjs)] # return object by reference
Class point
x = 10
y = 20
z = 30
Output:
x: 10.000000
y: 20.000000
z: 30.000000
x: 100.000000
y: 200.000000
z: 300.000000
41.2. Composition and Returning Objects and Lists by Reference 269

Example(2):
func main
o1 = new screen {
content[point()] {
x = 100
y = 200
z = 300
}
content[point()] {
x = 50
y = 150
z = 250
}
}
see o1.content[1]
see o1.content[2]
Class Screen
content = []
func point
content + new point
return len(content)
Class point
x = 10
y = 20
z = 30
Output:
x: 100.000000
y: 200.000000
z: 300.000000
x: 50.000000
y: 150.000000
z: 250.000000
Example(3):
func main
o1 = New Screen {
point() { # access the object using reference
x = 100
y = 200
z = 300
}
point() { # access the object using reference
x = 50
y = 150
z = 250
}
}
see o1.content[1]
see o1.content[2]
Class Screen
content = []
func point
content + new point
41.2. Composition and Returning Objects and Lists by Reference 270

return content[len(content)] # return the object by reference
Class point x=10 y=20 z=30
Output:
x: 100.000000
y: 200.000000
z: 300.000000
x: 50.000000
y: 150.000000
z: 250.000000
41.3 Executing code after the end of object access
We can access an object using { } to use object attributes and methods.
if the object contains a method called BraceEnd(), it will be executed before the end of the object access.
Example:
New Point { See "How are you?" + nl }
Class Point x y z
func braceend
see "I'm fine, Thank you!" + nl
Output:
How are you?
I'm fine, Thank you!
41.4 Declarative Programming on the top of Object-Oriented
The next features enable us to build and use declartive programming environment using nested structures on the top
of object oriented
• using {} to access the object attributes and methods
• BraceEnd() Method
• returning objects by reference
• Setter/Getter Methods (optional)
Example:
# Declartive Programming (Nested Structures)
Screen()
{
point()
{
x = 100
y = 200
z = 300
41.3. Executing code after the end of object access 271

}
point()
{
x = 50
y = 150
z = 250
}
}
# Functions and Classes
Func screen return new screen
Class Screen
content = []
func point
content + new point
return content[len(content)]
func braceend
see "I have " + len(content) + " points!"
Class point
x=10 y=20 z=30
func braceend
see self
Output:
x: 100.000000
y: 200.000000
z: 300.000000
x: 50.000000
y: 150.000000
z: 250.000000
I have 2 points!
41.5 More beautiful Code
We can get better results and a more beautiful code when we can avoid writing () after the method name when
the methods doesn’t take parameters. This feature is not provided directly by the Ring language because there is a
difference between object methods and object attributes. We can get a similar effect on the syntax of the code when
we define a getter method for the object attribute. For example instead of defining the point() method. we will define
the point attribute then the getpoint() method that will be executed once you try to get the value of the point attribute.
since we write the variable name direcly without () we can write point instead of point() and the method getpoint()
will create the object and return the object reference for us.
Example:
new Container
{
41.5. More beautiful Code 272

Point
{
x=10
y=20
z=30
}
}
Class Container
aObjs = []
point
func getpoint
aObjs + new Point
return aObjs[len(aObjs)]
Class Point x y z
func braceend
see "3D Point" + nl + x + nl + y + nl + z + nl
Output
3D Point
10
20
30
41.5. More beautiful Code 273

CHAPTER
FORTYTWO
NATURAL LANGUAGE PROGRAMMING
Using the Ring programming language, we can create Natural programming languages based on classes and objects.
42.1 History
In 2010, I developed a new programming language called Supernova (developed using PWCT). This language uses
a code that looks similar to Natural Language statements to create simple GUI applications. Now after five years, In
the Ring programming language, we can get similar results, but now we have the ability to create/use code similar to
Natural language statements in any domain that we like or need.
The Ring programming language comes with the Supernova sprite, but with more generalization and with mix of other
languages sprites.
42.2 Example
The next example presents how to create a class that define two instructions
The first instruction is : I want window
The second instruction is : Window title = <expr>
Also keywords that can be ignored like the ‘the’ keyword
New App
{
I want window
The window title = "hello world"
}
Class App
# Attributes for the instruction I want window
i want window
nIwantwindow = 0
# Attributes for the instruction Window title
# Here we don't define the window attribute again
title
nWindowTitle = 0
# Keywords to ignore, just give them any value
the=0
func geti
274

if nIwantwindow = 0
nIwantwindow++
ok
func getwant
if nIwantwindow = 1
nIwantwindow++
ok
func getwindow
if nIwantwindow = 2
nIwantwindow= 0
see "Instruction : I want window" + nl
ok
if nWindowTitle = 0
nWindowTitle++
ok
func settitle cValue
if nWindowTitle = 1
nWindowTitle=0
see "Instruction : Window Title = " + cValue + nl
ok
Output:
Instruction : I want window
Instruction : Window Title = hello world
42.3 Change the Ring Keyword ‘And’
What if we want to connect between the two instructions using ‘and’
We have a problem because in Ring ‘and’ is a keyword
We can change that using the ChangeRingKeyword command.
Syntax:
ChangeRingKeyword <oldkeyword> <newkeyword>
Note: remember to restore the keyword again
Tip: The ChangeRingKeyword command is executed in the scanner stage by the compiler (before parsing).
Example:
ChangeRingKeyword and _and
New App
{
I want window and the window title = "hello world"
}
Class App
42.3. Change the Ring Keyword ‘And’ 275

i want window
nIwantwindow = 0
title
nWindowTitle = 0
the=0 and=0
ChangeRingKeyword _and and
func geti
if nIwantwindow = 0
nIwantwindow++
ok
func getwant
if nIwantwindow = 1
nIwantwindow++
ok
func getwindow
if nIwantwindow = 2
nIwantwindow= 0
see "Instruction : I want window" + nl
ok
if nWindowTitle = 0
nWindowTitle++
ok
func settitle cValue
if nWindowTitle = 1
nWindowTitle=0
see "Instruction : Window Title = " + cValue + nl
ok
func getand
see "Using : and" + nl
Output:
Instruction : I want window
Using : and
Instruction : Window Title = hello world
42.4 Change the Ring Operator ‘+’
What if we want to deﬁne a new behavior for any operator like the “+” operator.
We can do this change using the ChangeRingOperator command to hide operator (change it’s name)
Then we can use the operator as identiﬁer that we can handle it’s behaviour
Syntax:
42.4. Change the Ring Operator ‘+’ 276

ChangeRingOperator <oldoperator> <newoperator>
Note: remember to restore the operator again
Tip: The ChangeRingOperator command is executed in the scanner stage by the compiler (before parsing).
Example:
ChangeRingOperator + _+
New App {
+
}
Class App
+
func get+
see "Plus operator"
ChangeRingOperator _+ +
Output:
Plus operator
42.5 Change the ‘=’ operator to ‘is’
Example:
ChangeRingKeyword and _and
ChangeRingOperator = is
New App
{
I want window and the window title is "hello world"
}
ChangeRingOperator is =
Class App
i want window
nIwantwindow = 0
title
nWindowTitle = 0
the=0 and=0
ChangeRingKeyword _and and
func geti
if nIwantwindow = 0
42.5. Change the ‘=’ operator to ‘is’ 277

The Ring programming language version 1.4 book - Part 10 of 30

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