The Ring programming language version 1.7 book - Part 42 of 196

Ring Documentation, Release 1.7
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!
46.5 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
{
46.5. More beautiful Code 382

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
46.5. More beautiful Code 383

CHAPTER
FORTYSEVEN
NATURAL LANGUAGE PROGRAMMING
Using the Ring programming language, we can create Natural programming languages based on classes and objects.
47.1 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 spirit, but with more generalization and with mix of other
languages spirits.
47.2 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
384

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
47.3 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
47.3. Change the Ring Keyword ‘And’ 385

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
ok
if nWindowTitle = 0
nWindowTitle++
ok
if nWindowTitle = 1
nWindowTitle=0
ok
func getand
see "Using : and" + nl
Output:
Instruction : I want window
Using : and
Instruction : Window Title = hello world
47.4 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:
47.4. Change the Ring Operator ‘+’ 386

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
47.5 Change the ‘=’ operator to ‘is’
Example:
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
func geti
if nIwantwindow = 0
47.5. Change the ‘=’ operator to ‘is’ 387

nIwantwindow++
ok
func getwant
if nIwantwindow = 1
nIwantwindow++
ok
func getwindow
if nIwantwindow = 2
nIwantwindow= 0
ok
if nWindowTitle = 0
nWindowTitle++
ok
if nWindowTitle = 1
nWindowTitle=0
ok
47.6 Using Eval() with our Natural Code
Example:
func Main
cProgram = ' I want window and the window title is "hello world" '
MyLanguage(cProgram)
Func MyLanguage cCode
# We add to the code the instructions that change keywords and operators
# Because Eval() uses a new Compiler Object (the original keywords and operatos).
cCode = '
ChangeRingOperator = is
' + cCode
New App
{
eval(cCode)
}
Class App
i want window
nIwantwindow = 0
47.6. Using Eval() with our Natural Code 388

title
nWindowTitle = 0
the=0
and=0
func geti
if nIwantwindow = 0
nIwantwindow++
ok
func getwant
if nIwantwindow = 1
nIwantwindow++
ok
func getwindow
if nIwantwindow = 2
nIwantwindow= 0
ok
if nWindowTitle = 0
nWindowTitle++
ok
if nWindowTitle = 1
nWindowTitle=0
ok
47.7 BraceStart and BraceEnd Methods
We can write code that will be executed before/after using { }
Example:
o1 = new test {
see "Hello" + nl
}
o1 {}
class test
func bracestart
see "start" + nl
func braceend
see "end" + nl
Output:
47.7. BraceStart and BraceEnd Methods 389

start
Hello
end
start
end
47.8 BraceExprEval Method
The next example demonstrates how to use the “BraceExprEval” method to get expressions in Natural code.
Example:
new natural {
create 5
}
class natural
create=0
lkeyword = false
func braceexpreval r
if lkeyword lkeyword=false return ok
see "expr eval" + nl
see "type: " + type(r) see nl
see "value : " see r see nl
func getcreate
lkeyword = true
see "create" + nl
Output:
create
expr eval
type: NUMBER
value : 5
47.9 Real Natural Code
The next example is a more advanced example
# Natural Code
new program {
Accept 2 numbers then print the sum
}
# Natural Code Implementation
class program
# Keywords
Accept=0 numbers=0 then=0 print=0 the=0 sum=0
# Execution
func braceexpreval x
value = x
func getnumbers
for x=1 to value
see "Enter Number ("+x+") :" give nNumber
47.8. BraceExprEval Method 390

aNumbers + nNumber
next
func getsum
nSUm = 0
for x in aNumbers nSum+= x next
see "The Sum : " + nSum
private
value=0 aNumbers=[]
Output:
Enter Number (1) :3
Enter Number (2) :4
The Sum : 7
47.10 BraceError() Method
The next examples demonstrates how to use the “BraceError” method to handle errors when accessing the object using
braces {}.
Example:
func main
o1 = new point {
x=10 y=20 z=30
TEST
SEE test
}
class point x y z
func braceerror
see "Handle Error!" + nl
SEE "Message :" + cCatchError + nl
if ( left(cCatchError,11) = "Error (R24)" ) and not isattribute(self,"test")
see "add attribute" + nl
addattribute(self,"test")
test = 10
ok
see "done" + nl
return
Output:
Handle Error!
Message :Error (R24) : Using uninitialized variable : test
add attribute
done
10
Example:
new point {
x=10 y=20 z=30
test()
see "mmm..." + NL
}
47.10. BraceError() Method 391

The Ring programming language version 1.7 book - Part 42 of 196

More Related Content

What's hot (20)

Similar to The Ring programming language version 1.7 book - Part 42 of 196 (20)

More from Mahmoud Samir Fayed (20)

Recently uploaded (20)

The Ring programming language version 1.7 book - Part 42 of 196