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
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.
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:
========================================
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
========================================
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()
func f3
see "f3 method" + nl
class local
Output:
========================================
test method
f1 function
f2 function
f3 method
f3 function
========================================