The Ring programming language version 1.4.1 book - Part 20 of 31

Ring Documentation, Release 1.4.1
• Local Scope —> Object Scope
And using Braces changes the object scope only (not the local scope) and when Ring search for variables it will search
in the Local Scope first so it will find self in the class that we are inside.
56.6 How Ring Define Variables and Attributes
Ring will use the variable name in the Assignment operation
1 - Search using the variable name
2 - If not found —> Avoid the runtime error and define the variable in the current scope
3 - If found —> Use the variable and don’t define anything in the current scope
• In the global region (before any function or class) the current scope is the global scope.
• In the class region (after the class name and before any method) the current scope is the object attributes.
• In Functions and methods the current scope is the local scope.
56.7 Conflict between Global Variables and Class Attributes
Look at this example:
name = "test"
o1 = new person
see o1
class person
name
address
phone
In the previous example we have a global variable called ‘name’ inside the class person.
when we use the variable ‘name’, Ring will start the search operation and will try to find it.
if found —> Use it
if not found —> Define new attribute
But the variable name is a global variable, so it will be found and used!
We will not have the attribute name! added to the object.
Solution (1) - Use the Main Function
func main
name = "test"
o1 = new person
see o1
class person
name
address
phone
Solution (2) - Use special mark for global variable names like $
56.6. How Ring Define Variables and Attributes 548

$name = "test"
o1 = new person
see o1
class person
name
address
phone
Solution (3) - Use the AddAttribute() Method
name = "test"
o1 = new person
see o1
class person
AddAttribute(self,"name")
address
phone
Solution (4) - Use self before the attribute name
name = "test"
o1 = new person
see o1
class person
self.name
address
phone
So what is the best solution to this conflict?
1 - Use the $ Mark for global variables
2 - Optional : Try to avoid global variables and use the Main function
In practice i do both of them.
The other solution
• Use self before the attribute name or use AddAttribute()
56.8 Conflict between Class Attributes and Local Variables
This conflict may happen when we access the object using braces
Example:
func main
name = "nice"
o1 = new person {name="mahmoud" address="Egypt" phone = 000 }
see o1
class person
name
address
phone
56.8. Conflict between Class Attributes and Local Variables 549

In the previous example we have the local variable name.
The value of this variable will be set to “mahmoud” instead of the object attribute.
Solution (1) : Just use Self
func main
name = "nice"
o1 = new person {self.name="mahmoud" address="Egypt" phone = 000 }
see o1
class person
name
address
phone
Solution (2) : Change the Local variable name
func main
cName = "nice"
o1 = new person {name="mahmoud" address="Egypt" phone = 000 }
see o1
class person
name
address
phone
Solution (3) : Change Braces and use the Dot operator
func main
name = "nice"
o1 = new person
o1.name ="mahmoud"
o1.address ="Egypt"
o1.phone = 000
see o1
class person
name
address
phone
56.9 Using Braces to access objects inside Class Methods
Remember that we have Three scopes (Local Scope, Object Scope and Global Scope) and when we are inside a class
method, we expect that we have access to the object attributes and methods and this is true until we use braces to
access another object attributes and methods because in this case our object scope will be switched to another object.
new point { test() }
class point
x=10 y=20
func test
see x + nl + y + nl # works fine
myobj = new otherclass {
see name + nl
see x + nl + y + nl # error !
56.9. Using Braces to access objects inside Class Methods 550

}
class otherclass
name = "test"
Output:
10
20
test
Line 8 Error (R24) : Using uninitialized variable : x
In method test() in file methodbraceerror.ring
called from line 5 in file methodbraceerror.ring
Now what we will do to solve the previous problem?
Solution (1) : Write the code that access the class attributes outside braces.
class point
x=10 y=20
func test
see x + nl + y + nl # works fine
see name + nl
}
see x + nl + y + nl # Outside braces - works fine
class otherclass
name = "test"
Output:
10
20
test
10
20
Solution (2) : Don’t Use Braces
class point
x=10 y=20
func test
see x + nl + y + nl
myobj = new otherclass
see myobj.name
see x + nl + y + nl
class otherclass
name = "test"
Solution (3) : Copy the self object
We may use this solution if we want to use braces and get access to the class attributes (Just Reading).

class point
x=10 y=20
func test
oSelf = self
see x + nl + y + nl
see name + nl
see oself.x + nl + oself.y + nl
}
class otherclass
name = "test"
Output:
10
20
test
10
20
Now look at this line
oself = self
The problem with the previous line is that we will have a new copy from the object Because in Ring the assignment
operator copy lists and objects by value (not by reference).
When we access the new object attributes (reading) we don’t have problems
But if we modiﬁed the object attributes (Then we will modify the copy!).
Note: We can use braces again with the copy
class point
x=10 y=20
func test
oSelf = self
see x + nl + y + nl
see name + nl
oSelf {
see x + nl + y + nl
}
}
class otherclass
name = "test"
In a GUI application, we may create a class contains the window objects as attributes to be able to access the controls
from different methods. Remember the previous information when you try to access objects using braces inside
methods because in this case you can’t access the object attributes directly and if you copied the self object you will
work on a copy and the new controls that you create will be related to the copy and you can’t access them.

56.10 Accessing the class attributes from braces inside class meth-
ods
We access the class attributes directly from the class methods, also we have the choice to use the Self reference before
the attribute/method name. Using Braces {} inside class method change the active object scope and prevent us from
getting direct access to the class attributes. Also using Self will not help because the Self reference will be changed to
the object that we access using Braces.
In this case if you want to read an attribute you have to copy the Self object before using Braces and if you want to
modify an attribute you have to the copy from local variable to the object attribute after using Braces.
This case happens when you want to read/modify attribute insead braces.
Class MyApp
oCon # Attribute
# some code here
Func OpenDatabase
# some code here
new QSqlDatabase() {
oCon = addDatabase("QSQLITE") {
setDatabaseName("weighthistory.db")
open()
}
}
self.oCon = oCon
# some code here
In the previous example we want to create the connection object and save it inside the oCon attribute.
The object is an output from the addDatabase() method that we use after accessing the QSQLDatabase() object.
Inside braces we can’t use the Self reference to use the object created from the MyApp class, Because the Self reference
here will be to the object that we access using Braces.
We solved the problem in the previous example by creating a local variable called oCon then after Braces we copied
that variable to the oCon attribute.
The next code is another solution.
Class MyApp
oCon # Attribute
# some code here
Func OpenDatabase
# some code here
oCon = new QSqlDatabase()
oCon = oCon.addDatabase("QSQLITE") {
Open()
}
# some code here
The next code is a better solution.
56.10. Accessing the class attributes from braces inside class methods 553

Class MyApp
oCon # Attribute
# some code here
Func OpenDatabase
# some code here
new QSqlDatabase() {
this.oCon = addDatabase("QSQLITE") {
Open()
}
}
# some code here
Note: We used this.attribute to access the class attribute (oCon) while we are inside Braces.
56.11 Creating a Class for each Window in GUI applications
A good way for creating classes for windows is to deﬁne the window directly after the class name
In this area you can use nested braces without problems to deﬁne the window and the controls, and they will be
attributes that you can access from methods.
Example:
Load "guilib.ring"
new qApp
{
$ObjectName = "oFirstWindow"
oFirstWindow = new FirstWindow
$ObjectName = "oSecondWindow"
oSecondWindow = new SecondWindow
exec()
}
Class FirstWindow
win = new qWidget() {
setgeometry(0,50,300,200)
setWindowTitle("First Window")
label1 = new qLabel(win)
{
setText("0")
}
btn1 = new qPushButton(win)
{
move(100,100)
setText("Increment")
setClickEvent($ObjectName+".increment()")
}
56.11. Creating a Class for each Window in GUI applications 554

show()
}
Func Increment
label1 {
setText( "" + ( 0 + text() + 1 ) )
}
Class SecondWindow
win = new qWidget() {
setWindowTitle("Second Window")
label1 = new qLabel(win)
{
setText("0")
}
btn1 = new qPushButton(win)
{
move(100,100)
setText("Decrement")
setClickEvent($ObjectName+".decrement()")
}
show()
}
Func Decrement
label1 {
setText( "" + ( 0 + text() - 1 ) )
}
56.12 Conflict between self inside braces and self in the class region
In the class region (after the class name and before any methods) we define the attributes.
In this region we have access to the global scope and the local scope will point to the object scope.
Three Scopes
• Global Scope —> Gloabl Scope
• Object Scope —> Object Scope
• Local Scope —> Object Scope
Look at this example
New Account {
see aFriends
}
Class Account
name = "Mahmoud"
aFriends = []
aFriends + new Friend {
name = "Gal"
56.12. Conflict between self inside braces and self in the class region 555

}
name = "Bert"
}
Class Friend
name
Output:
name: NULL
name: NULL
The problem in the previous example is that the Class account contains an attribute called “name” and the Friend class
contains an attribue called “name” also.
If you tried using self.name inside braces you will get the same result!
New Account {
see aFriends
}
Class Account
name = "Mahmoud"
aFriends = []
self.name = "Gal"
}
self.name = "Bert"
}
Class Friend
name
So why using self.name inside braces doesn’t solve this conﬂict?
Because after the class region we have
• global scope —> global scope
• object scope —> object scope (Account Class)
• local scope —> local scope (Account Class)
When we use braces we change the object scope, so we have
• global scope —> global scope
• object scope —> object scope (Friend Class)
• local scope —> local scope (Account Class)
Ring search in the local scope ﬁrst, so using self.name will use the Account class.
There are many solution
Solution (1) : Access the object through the list
New Account {
see aFriends
}
Class Account

name = "Mahmoud"
aFriends = []
aFriends + new Friend
aFriends[len(aFriends)] {
aFriends[len(aFriends)].name = "Gal"
}
aFriends[len(aFriends)] {
aFriends[len(aFriends)].name = "Bert"
}
Class Friend
name
Solution (2) : Create Method in the friend class to set the name attribute.
New Account {
see aFriends
}
Class Account
name = "Mahmoud"
aFriends = []
setname("Gal")
}
setname("Bert")
}
Class Friend
name
func setname cName
name = cName
Solution (3) : Create a method in the account class to set the attribute
New Account {
see aFriends
}
Class Account
name = "Mahmoud"
aFriends = []
friend("Gal")
friend("Bert")
func friend cName
name = cName
}
Class Friend
name
Solution (4) : Declarative Programming
New Account {
name = "mahmoud"
friend {

name = "Gal"
}
friend {
name = "Bert"
}
see aFriends
}
Class Account
name
aFriends = []
friend
func getfriend
return aFriends[len(aFriends)]
Class Friend
name
Output:
name: Gal
name: Bert
56.13 Using braces to escape from the current object scope
Since braces change the current object scope to another object. we can use it to do some work without modifying the
class attributes and using the same variable names.
new point {x=10 y=20 z=30 start() }
class point x y z
func start
see self # print the x y z values (10,20,30)
new Local {
x = 100
y = 200
z = 300
}
see self # print the x y z values (10,20,30)
see x + nl # will print 100
see y + nl # will print 200
see z + nl # will print 300
Self { # NO Advantage - Search is done in local scope first
see x + nl # will print 100
see y + nl # will print 200
see z + nl # will print 300
}
see self.x + nl # will print 10
see self.y + nl # will print 20
see self.z + nl # will print 30
class Local
Output:
x: 10.000000
y: 20.000000
56.13. Using braces to escape from the current object scope 558

z: 30.000000
x: 10.000000
y: 20.000000
z: 30.000000
100
200
300
100
200
300
10
20
30
56.14 Summary of Scope Rules
At first remember that
1 - Each programming language comes with it’s scope rules based on the language goals
2 - Programming in the small is different than Programming in the Large
3 - Some programming language are designed for developing small programs while others are designed for large
programs
4 - In programming, If we have access to more than one scope - Then problems may come if we don’t manage things
correctly
5 - It’s always more secure to reduce the number of visible scopes
6 - Some programming languages force you to manage the scope in some way, while others not!
In Ring
1 - Special and very simple scope rules that are designed for Flexibility first then Security
2 - Ring is designed to support programming in the small and programming in the large.
3 - The language provide the different programming paradigms that you may select from based on the project size.
Errors comes only if you selected a bad paradigm for the target project or you are using the paradigm in a way that is
not correct or at least not common.
4 - In Ring you have the choice, you can use global variables or avoid them. you can give them a special $ mark or
leave them. you can use object-oriented or stay with procedures. you can use the class region (after the class name
and before any method) just for attributes or use it for code too.
5 - Just read the next scope rules and think about them then use them in your favorite way.
Scope Rules:
1 - At any place in our program code we have only at maximum Three Scopes (Local Scope, Object Scope and Global
Scope).
2 - When Ring find a variable it will search in the local scope first then in the object scope then in the global scope.
3 - At any time inside procedures or methods you can use braces { } to access an object and change the current object
scope.
4 - In the class region (After the class name and before any method) this is a special region where both of the object
scope and the local scope point to the object scope. I.e. No local variables where each variable you define in this
region will become an attribute.
56.14. Summary of Scope Rules 559

5 - Before defining any variable (in any scope and in the class region too) a search process will be done to use the
variable if it’s found.
6 - Functions and Methods parameters are defined automatically as local variables to these functions or methods.
7 - Using Object.Attribute will search in the object attributes only.
8 - Using Self.Attribute will lead to a search for Self first then search in Self Attributes.
9 - The Self reference inside class region (after the class name and before any method) always point to the object scope
created from the class.
10- The Self reference inside methods will be changed when we uses Braces to be a reference to the object that we
access.
11- Writing variable names directly in the class region (after the class name and before any method) means using them
or define then (in order).
12- Using self.attribute in the class region reduce search to the object scope (avoid conflict with global scope).
From these rules you can understand all types of conflicts and why you may have them and how to avoid them
Simple advices to avoid any conflict and use the scope rules in a better way
1 - Try to avoid global variables
2 - Use the Main Function - This will help you to avoid global variables
3 - If you are going to use many global variables use the $ mark before the variable name
4 - In the class region if you don’t respect the advice number three ($) then use self.attribute when you define your
attributes
5 - You can use object.attribute and object.method() instead of object { attribute } and object { method() } if you don’t
like changing the object scope.
6 - If you will use nested braces in a class - think about using the class region if possible because in this region you
will have access to the object that you access using { } + access to the class attributes
7 - If you are inside a class method and used nested braces you will change the object scope with each brace and you
will loss the access to the class attributes directly but you have access to the local scope before and after using brace
{ } , if you will read/modify the class attribute from braces then use This.Attribute because using ‘This’ means (The
object created from this class) while using ‘Self’ means (The object in the current object scope).
After understanding all of the previous points, You will master this topic.
56.14. Summary of Scope Rules 560

CHAPTER
FIFTYSEVEN
SCOPE RULES FOR FUNCTIONS AND METHODS
In this chapter we will learn about the scope rules for functions and methods.
You need to know the next information once you started using Ring for large applications.
These applications may contains and use
• Many Packages and Classes written in Ring
• Many Functions written in Ring
• Standard Ring Functions (Written in C language)
• Functions and Classes written in C/C++ languages
57.1 How Ring find the Functions and Methods?
When you call a method or function, Ring will start a search process to find this function
If found –> Call the function and store the function pointer in the cache so Ring can use it again with doing another
search.
If not found —> Runtime error message (That you can avoid using Try/Catch)
How the search process is done?
Search for functions/methods follow the next order
1 - Search in methods (if we are inside class method or object using braces {})
2 - Search in functions written by the programmer using Ring Code
3 - Search in functions written in C/C++ like standard Ring functions
This enable us to write clean code inside classes methods and avoid any conflict with functions.
If we want to call a function with the same name as a method in the class we will need a wrapper function or we will
access a temp. object using { } then call that function there.
We can replace C/C++ Functions with Ring Functions.
We can replace Ring Functions with Ring Methods.
Note: Using self.method() is not necessary in any use case.
Tip: We can use this.method() to escape from the current active scope that we access using braces {} and call a
method in the class that we are inside.
561

57.2 Example about Sharing Names between Functions and Methods
Look at the next example
func main
o1 = new myclass { test() test2() }
test2()
func f1
see "f1 function" + nl
func f2
func f3
func test2
myline()
see "test2 function" + nl
new myclass {
f1()
f2()
f3()
self.f3()
}
myobj = new myclass
myobj.f3()
myline()
func myline
see copy("=",40) + nl
Class myclass
func test
myline()
see "test method" + nl
f1()
f2()
f3()
myline()
func f3
see "f3 method" + nl
func test2
myline()
see "test2 method" + nl
self {
f1()
f2()
f3()
}
myline()
Output:
57.2. Example about Sharing Names between Functions and Methods 562

========================================
test method
f1 function
f2 function
f3 method
========================================
========================================
test2 method
f1 function
f2 function
f3 method
========================================
========================================
test2 function
f1 function
f2 function
f3 method
f3 method
f3 method
========================================
57.3 Calling a function sharing the name with a method in the current
class
In the previous example we have a function called f3() and we have a method called f3()
How we can call the f3() function from the test() method ?
Solution (1) : Change the current object scope to another object scope
In this solution we will have an empty class called local that we will use to change the current object scope.
func main
o1 = new myclass { test()}
func f1
func f2
func f3
func myline
see copy("=",40) + nl
Class myclass
func test
myline()
see "test method" + nl
f1()
f2()
f3() # call f3() method
new local { f3() } # call f3() function
myline()
57.3. Calling a function sharing the name with a method in the current class 563

func f3
see "f3 method" + nl
class local
Output:
========================================
test method
f1 function
f2 function
f3 method
f3 function
========================================
57.3. Calling a function sharing the name with a method in the current class 564

CHAPTER
FIFTYEIGHT
SYNTAX FLEXIBILITY
In this chapter we will learn about some options that are provided automatically by the Ring compiler for syntax
ﬂexibility.
58.1 Change Language Keywords
We can change any keyword using the ChangeRingKeyword command.
Note: Remember to restore the keyword again if the team will mix between styles in the same project.
Tip: The ChangeRingKeyword command is executed in the scanner stage by the compiler (before parsing).
Syntax:
ChangeRingKeyword <oldkeyword> <newkeyword>
Example:
ChangeRingKeyword see print
print "welcome" + nl
ChangeRingKeyword print see
see "Welcome" + nl
Example:
ChangeRingKeyword func function
ChangeRingKeyword ok endif
ChangeRingKeyword next endfor
ChangeRingKeyword end endwhile
x = 10
while x > 0
print "x = " + x + nl
for t = 1 to 10
if t = 3
print "number three" + nl
endif
endfor
565

x--
endwhile
test()
function test
print "message from test" + nl
ChangeRingKeyword function func
ChangeRingKeyword endif ok
ChangeRingKeyword endfor next
ChangeRingKeyword endwhile end
58.2 Change Language Operators
We can change any operator using the ChangeRingOperator command.
Note: Remember to restore the operator again if the team will mix between styles in the same project.
Tip: The ChangeRingOperartor command is executed in the scanner stage by the compiler (before parsing).
Syntax:
ChangeRingOperator <oldkeyword> <newkeyword>
Example:
The next program hide the + operator by changing it to _+
changeringoperator + _+
changeringkeyword SEE PRINT
try
print 5 + 10
catch
print nl print "error" print nl
done
changeringoperator _+ +
The next program change the + operator to “plus”.
changeringoperator + plus
changeringkeyword SEE PRINT
Print 5 plus 5
changeringoperator plus +
changeringkeyword PRINT SEE
58.2. Change Language Operators 566

58.3 Load Syntax Files
You may store a group of ChangeRingKeyword and ChangeRingOperator commands in a file to use later in many
source files. You can’t use the Load command to call these files because
• ChangeRingKeyword and ChangeRingOperator commands are executed in the scanner phase by the compiler
(before parsing).
• The load command is executed in the parsing phase (after the scanner phase).
Solution: Use the LoadSyntax Command which is executed in the scanner phase.
Syntax:
LoadSyntax "syntaxfile.ring"
Example:
File : StyleBasicOn.ring
ChangeRingKeyword ok endif
ChangeRingKeyword next endfor
ChangeRingKeyword end endwhile
File : StyleBasicOff.ring
ChangeRingKeyword endif ok
ChangeRingKeyword endfor next
ChangeRingKeyword endwhile end
File : UseStyleBasic.ring
LoadSyntax "stylebasicon.ring"
x = 10
while x > 0
print "x = " + x + nl
for t = 1 to 10
if t = 3
print "number three" + nl
endif
endfor
x--
endwhile
LoadSyntax "stylebasicoff.ring"
see "done" + nl
Note: files called by the LoadSyntax command must contains ChangeRingKeyword and ChangeRingOperator com-
mands only.
Tip: files called by the LoadSyntax command doesn’t support functions, packages and classes. just imperative
commands only.
Note: Using this feature you can create many styles that you can use in the same project and you can support Ring
58.3. Load Syntax Files 567

translation to other languages like Arabic, French and so on.
58.4 Using “()” around the function parameters
We can use () around the function parameters (optional).
Example:
hello()
sum(3,4)
func hello()
see "Hello" + nl
func sum(x,y)
see x+y+nl
Output:
Hello
7
Example:
myfunc = func x,y { see x + y + nl }
call myfunc (3,4)
myfunc2 = func (x,y) { see x+y+nl }
call myfunc(3,4)
Output:
7
7
58.5 Using Semi-colon after and between statements
In Ring we can use semi-colon after and between statements (optional).
Example:
# Using semi-colon is optional
see "Hello" + nl ; see "How are you?" + nl ; see "Welcome to Ring" + nl ;
one() ; two() ; three() ;
func one ; see "one" + nl ;
func two ; see "two" + nl ;
func three ; see "three" + nl ;
Output:
Hello
How are you?
Welcome to Ring
58.4. Using “()” around the function parameters 568

one
two
three
58.6 Using $ and @ in the start of the variable name
You can use any unicode character in the variable name also we can use $ and @ in the name.
This feature may help, for example we can start global variables with $ and the object attributes with @.
In other languages like Ruby this is the rule, In the Ring language this is just an option without any force from the
Compiler.
example:
$global_variable = 5
new test { hello() }
class test
@instance_variable = 10
func hello
local_variable = 15
see "Global : " + $global_variable + nl +
"Instance : " + @instance_variable + nl +
"Local : " + local_variable + nl
Output:
Global : 5
Instance : 10
Local : 15
58.7 Using the ‘elseif’ keyword as ‘but’ in if statement
if you don’t like the ‘but’ keyword in if statement Then you can use the ‘elseif’ keyword.
Example:
give x
if x = 1 see "one"
elseif x=2 see "two"
elseif x=3 see "three"
elseif x=4 see "four"
else see "other"
ok
see nl
58.6. Using $ and @ in the start of the variable name 569

58.8 Using the ‘else’ keyword as ‘other’ in switch statement
if you don’t like the ‘other’ keyword in switch statement Then you can use the ‘else’ keyword.
Also you can replace ‘else’ with ‘other’ in if statement.
i.e. ‘other’ keyword is the same as ‘else’ keyword.
Example:
x = 1
switch x
on 10
see "10" + nl
else
see "not 10" + nl
end
Output:
not 10
58.9 Using the ‘end’ keyword in different control structures
We can use the ‘end’ keyword to close different control structures
• If statement
• For loop
• Switch
• While
• Try-Catch
Example:
see "if statement.." + nl
x = 1
if x = 1
see "one" + nl
elseif x=2
see "two" + nl
elseif x=3
see "three" + nl
end
see "for loop.." + nl
for t = 1 to 10
see t
end
see nl
see "switch..." + nl
x = 1
switch x
on 1 see "one" + nl
on 2 see "two" + nl
end
58.8. Using the ‘else’ keyword as ‘other’ in switch statement 570

see "try catch..." + nl
try
x = 1 / 0
catch
see "catching error" + nl
end
Output:
if statement..
one
for loop..
12345678910
switch...
one
try catch...
catching error
58.10 Using braces to start and end different control structures
We can use braces { } to start and end different control structures
• If statement
• For loop
• Switch
• While
• Try-Catch
Example:
see "if statement.." + nl
x = 1
if x = 1 {
see "one" + nl
elseif x=2
see "two" + nl
elseif x=3
see "three" + nl
}
see "for loop.." + nl
for t = 1 to 10 {
see t
}
see nl
see "switch..." + nl
x = 1
switch x {
on 1 see "one" + nl
on 2 see "two" + nl
}
see "try catch..." + nl
try {
58.10. Using braces to start and end different control structures 571

x = 1 / 0
catch
see "catching error" + nl
}
Output:
if statement..
one
for loop..
12345678910
switch...
one
try catch...
catching error
58.11 Using ‘put’ and ‘get’ as ‘see’ and ‘give’
We can replace the ‘see’ keyword with the ‘put’ keyword.
Also we can replacew the ‘give’ keyword with the ‘get’ keyword.
Example:
put "Hello World" + nl
put "Enter Your Name ? " Get Name
Put "Hello " + Name
58.12 Using ‘case’ as ‘on’ in switch statements
We can replace the ‘on’ keyword with ‘case’ keyword in the switch statement.
Example (1) :
for x=1 to 10
switch x
case 1 put "one" + nl
case 2 put "two" + nl
case 3 put "thre" + nl
else put "else" + nl
end
end
Example (2) :
for x=1 to 10 {
switch x {
case 1 put "one" + nl
case 2 put "two" + nl
case 3 put "thre" + nl
else put "else" + nl
}
}
58.11. Using ‘put’ and ‘get’ as ‘see’ and ‘give’ 572

58.13 Using ‘def’ as ‘func’ in functions/methods definition
We can use the ‘def’ keyword as the ‘func’ keyword to define functions and methods.
Example:
one() two()
def one put "one" + nl
def two put "two" + nl
58.13. Using ‘def’ as ‘func’ in functions/methods definition 573

CHAPTER
FIFTYNINE
DISTRIBUTING RING APPLICATIONS
In this chapter we will learn about distributing Ring applications.
59.1 Distributing Applications for Microsoft Windows
Step 1:
Copy c:ringbin folder to be for example c:myapp
Step 2:
Rename c:myappring.exe to c:myappmyapp.exe
Step 3:
Create a file c:myappring.ring
And write
Load "myapp.ring"
When you run myapp.exe the file ring.ring will be executed automatically
So your file myapp.ring will be called and executed
Or just rename myapp.ring to ring.ring
It’s a fast way to distribute applications.
59.2 Protecting the Source Code
Step 1:
Execute the next command
ring myapp.ring -go
This will generate one object file (myapp.ringo) from the project files (*.ring)
Step 2:
Rename myapp.ringo to ring.ringo
When you run the executable file (ring.exe) or (myapp.exe) the file ring.ringo will be executed.
574

59.3 Creating Windows Installer
There are many tools that you can use to distribute your application.
Check : nullsoft scriptable install system
URL : http://nsis.sourceforge.net/Main_Page
59.4 Using C/C++ Compiler and Linker
Another method to distribute applications is to use a C/C++ compiler.
Ring can be embedded in C/C++ projects, We can create executable ﬁles using a C/C++ compiler by embedding the
Ring language in our project.
Check the “Embedding Ring Language in C/C++ Programs” chapter.
Using this way we will avoid using ring.ring or ring.ringo ﬁles.
59.5 Distributing Applications and Games for Mobile
Ring can be embedded in a Qt projects or LibSDL projects to build Mobile applications and Games.
You can build the Qt project or the LibSDL project and get the Android package directly (*.apk)
Check Ring distributions for Mobile development using Qt or LibSDL.
59.3. Creating Windows Installer 575

CHAPTER
SIXTY
COMMAND LINE OPTIONS
The ring language takes source code file (.ring) or the object file (.ringo) as input to execute, also the language provide
other options like
Option Description
-tokens Print a list of tokens in the source code file
-rules Print grammar rules applied on the tokens
-ic Print the intermediate byte code (before execution)
-icfinal Print the final byte code (after execution)
-cgi Print http response header before error messages
-norun Don’t run the program after compiling
-ins Print instruction operation code before execution
-performance Print clock before and after program execution
-go Generate Object File
-w Display Warnings
60.1 Printing Tokens
Example:
Func Main
See "Hello World" + nl
for x = 1 to 10
see x + nl
next
test()
func test
see "welcome" + nl
o1 = new point { x=10 y=20 z=30 }
see o1
class point x y z
Command:
ring test.ring -tokens -norun
Output:
===================================================
Tokens - Generated by the Scanner
===================================================
576

Keyword : FUNC
Identifier : main
EndLine
Keyword : SEE
Literal : Hello World
Operator : +
Identifier : nl
EndLine
Keyword : FOR
Identifier : x
Operator : =
Number : 1
Keyword : TO
Number : 10
EndLine
Keyword : SEE
Identifier : x
Operator : +
Identifier : nl
EndLine
Keyword : NEXT
EndLine
Identifier : test
Operator : (
Operator : )
EndLine
Keyword : FUNC
Identifier : test
EndLine
Keyword : SEE
Literal : welcome
Operator : +
Identifier : nl
EndLine
Identifier : o1
Operator : =
Keyword : NEW
Identifier : point
Operator : {
Identifier : x
Operator : =
Number : 10
Identifier : y
Operator : =
Number : 20
Identifier : z
Operator : =
Number : 30
Operator : }
EndLine
Keyword : SEE
Identifier : o1
EndLine
Keyword : CLASS
Identifier : point
Identifier : x
Identifier : y
Identifier : z
60.1. Printing Tokens 577

The Ring programming language version 1.4.1 book - Part 20 of 31

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