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Ring Documentation, Release 1.3
show()
}
Func Increment
label1 {
setText( "" + ( 0 + text() + 1 ) )
}
Class SecondWindow
win = new qWidget() {
setgeometry(400,50,300,200)
setWindowTitle("Second Window")
label1 = new qLabel(win)
{
setgeometry(10,10,300,30)
setText("0")
}
btn1 = new qPushButton(win)
{
move(100,100)
setText("Decrement")
setClickEvent($ObjectName+".decrement()")
}
show()
}
Func Decrement
label1 {
setText( "" + ( 0 + text() - 1 ) )
}
53.12 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"
53.12. Conflict between self inside braces and self in the class region 528
Ring Documentation, Release 1.3
}
aFriends + new Friend {
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 = []
aFriends + new Friend {
self.name = "Gal"
}
aFriends + new Friend {
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
53.12. Conflict between self inside braces and self in the class region 529
Ring Documentation, Release 1.3
name = "Mahmoud"
aFriends = []
aFriends + new Friend
aFriends[len(aFriends)] {
aFriends[len(aFriends)].name = "Gal"
}
aFriends + new Friend
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 = []
aFriends + new Friend {
setname("Gal")
}
aFriends + new Friend {
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
aFriends + new Friend {
name = cName
}
Class Friend
name
Solution (4) : Declarative Programming
New Account {
name = "mahmoud"
friend {
53.12. Conflict between self inside braces and self in the class region 530
Ring Documentation, Release 1.3
name = "Gal"
}
friend {
name = "Bert"
}
see aFriends
}
Class Account
name
aFriends = []
friend
func getfriend
aFriends + new Friend
return aFriends[len(aFriends)]
Class Friend
name
Output:
name: Gal
name: Bert
53.13 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
53.13. Using braces to escape from the current object scope 531
Ring Documentation, Release 1.3
z: 30.000000
x: 10.000000
y: 20.000000
z: 30.000000
100
200
300
100
200
300
10
20
30
53.14 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.
53.14. Summary of Scope Rules 532
Ring Documentation, Release 1.3
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.
53.14. Summary of Scope Rules 533
CHAPTER
FIFTYFOUR
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
54.1 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.
534
Ring Documentation, Release 1.3
54.2 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
see "f2 function" + nl
func f3
see "f3 function" + nl
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:
54.2. Example about Sharing Names between Functions and Methods 535
Ring Documentation, Release 1.3
========================================
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
========================================
54.3 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
see "f1 function" + nl
func f2
see "f2 function" + nl
func f3
see "f3 function" + nl
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()
54.3. Calling a function sharing the name with a method in the current class 536
Ring Documentation, Release 1.3
func f3
see "f3 method" + nl
class local
Output:
========================================
test method
f1 function
f2 function
f3 method
f3 function
========================================
54.3. Calling a function sharing the name with a method in the current class 537

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The Ring programming language version 1.3 book - Part 56 of 88

  • 1. Ring Documentation, Release 1.3 show() } Func Increment label1 { setText( "" + ( 0 + text() + 1 ) ) } Class SecondWindow win = new qWidget() { setgeometry(400,50,300,200) setWindowTitle("Second Window") label1 = new qLabel(win) { setgeometry(10,10,300,30) setText("0") } btn1 = new qPushButton(win) { move(100,100) setText("Decrement") setClickEvent($ObjectName+".decrement()") } show() } Func Decrement label1 { setText( "" + ( 0 + text() - 1 ) ) } 53.12 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" 53.12. Conflict between self inside braces and self in the class region 528
  • 2. Ring Documentation, Release 1.3 } aFriends + new Friend { 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 = [] aFriends + new Friend { self.name = "Gal" } aFriends + new Friend { 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 53.12. Conflict between self inside braces and self in the class region 529
  • 3. Ring Documentation, Release 1.3 name = "Mahmoud" aFriends = [] aFriends + new Friend aFriends[len(aFriends)] { aFriends[len(aFriends)].name = "Gal" } aFriends + new Friend 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 = [] aFriends + new Friend { setname("Gal") } aFriends + new Friend { 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 aFriends + new Friend { name = cName } Class Friend name Solution (4) : Declarative Programming New Account { name = "mahmoud" friend { 53.12. Conflict between self inside braces and self in the class region 530
  • 4. Ring Documentation, Release 1.3 name = "Gal" } friend { name = "Bert" } see aFriends } Class Account name aFriends = [] friend func getfriend aFriends + new Friend return aFriends[len(aFriends)] Class Friend name Output: name: Gal name: Bert 53.13 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 53.13. Using braces to escape from the current object scope 531
  • 5. Ring Documentation, Release 1.3 z: 30.000000 x: 10.000000 y: 20.000000 z: 30.000000 100 200 300 100 200 300 10 20 30 53.14 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. 53.14. Summary of Scope Rules 532
  • 6. Ring Documentation, Release 1.3 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. 53.14. Summary of Scope Rules 533
  • 7. CHAPTER FIFTYFOUR 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 54.1 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. 534
  • 8. Ring Documentation, Release 1.3 54.2 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 see "f2 function" + nl func f3 see "f3 function" + nl 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: 54.2. Example about Sharing Names between Functions and Methods 535
  • 9. Ring Documentation, Release 1.3 ======================================== 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 ======================================== 54.3 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 see "f1 function" + nl func f2 see "f2 function" + nl func f3 see "f3 function" + nl 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() 54.3. Calling a function sharing the name with a method in the current class 536
  • 10. Ring Documentation, Release 1.3 func f3 see "f3 method" + nl class local Output: ======================================== test method f1 function f2 function f3 method f3 function ======================================== 54.3. Calling a function sharing the name with a method in the current class 537