The Ring programming language version 1.8 book - Part 43 of 202

Ring Documentation, Release 1.8
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()
}
46.16 MySQL Class
Methods:
Method Description/Output
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
46.16. MySQL Class 391

Execute Query
Print Result
Id
Name
Salary
1
Mahmoud
15000
2
Samir
16000
3
Fayed
17000
Close database
46.17 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
46.17. SQLite Class 392

see t[2] + nl
next
next
see copy("*",50) + nl
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
46.18 Security Class
Methods:
md5(cString) Calculate the MD5 hash.
sha1(cString) Calculate the SHA1 hash.
encrypt(cString,cKey,cIV) Encrypts 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:
46.18. Security Class 393

Load "stdlib.ring"
oSecurity = new security
See "Test the security Class Methods" + nl
oSecurity {
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
}
46.19 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")
}
46.19. Internet Class 394

CHAPTER
FORTYSEVEN
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
47.1 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
395

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
47.2 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 caller 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
Example(2):
47.2. Composition and Returning Objects and Lists by Reference 396

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
return content[len(content)] # return the object by reference
47.2. Composition and Returning Objects and Lists by Reference 397

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
47.3 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!
47.4 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
}
47.3. Executing code after the end of object access 398

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!
47.5 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
{
Point
{
47.5. More beautiful Code 399

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
47.5. More beautiful Code 400

The Ring programming language version 1.8 book - Part 43 of 202

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The Ring programming language version 1.8 book - Part 43 of 202