The Ring programming language version 1.5.4 book - Part 32 of 185
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This document provides information on reflection and meta-programming in Ring programming language. Some key functions discussed include locals(), globals(), functions(), cfunctions(), islocal(), isglobal(), isfunction(), iscfunction(), packages(), ispackage(), classes(), isclass(), and packageclasses(). These functions allow programmers to get information about variables, functions, classes, and packages defined in their program at runtime. This enables dynamic programming features like modifying code during execution.
![Ring Documentation, Release 1.5.4
Func Test
see "Message from the test function!" + nl
Func Times nCount,F
for x = 1 to nCount
Call F()
next
Output:
Message from the test function!
Message from the test function!
Message from the test function!
Message from the test function!
Message from the test function!
40.4 Anonymous and Nested Functions
Anonymous Functions are functions without names that can be passed as parameters to other functions or stored in
variables.
Syntax:
Func [Parameters] { [statements] }
Example:
test( func x,y {
see "hello" + nl
see "Sum : " + (x+y) + nl
} )
new great { f1() }
times(3, func { see "hello world" + nl } )
func test x
call x(3,3)
see "wow!" + nl
func times n,x
for t=1 to n
call x()
next
Class great
func f1
f2( func { see "Message from f1" + nl } )
func f2 x
call x()
Output:
hello
Sum : 6
40.4. Anonymous and Nested Functions 285](https://image.slidesharecdn.com/311ringfayedringdoc1-180426033401/85/The-Ring-programming-language-version-1-5-4-book-Part-32-of-185-1-320.jpg)
![Ring Documentation, Release 1.5.4
wow!
Message from f1
hello world
hello world
hello world
Example:
Func Main
aList = [1,2,3,4]
Map (aList , func x {
return x*x
} )
see aList
aList = [4,9,14,25]
Map(aList, :myfilter )
see aList
aList = [11,12,13,14]
Map (aList , func x {
if x%2=0
return "even"
else
return "odd"
ok
})
see aList
Func myfilter x
if x = 9
return "True"
else
return "False"
ok
Func Map aList,cFunc
for x in aList
x = call cFunc(x)
next
Output:
1
4
9
16
False
True
False
False
odd
even
odd
even
40.5 Equality of functions
We can test if function = function or not using the ‘=’ or ‘!=’ operators
40.5. Equality of functions 286](https://image.slidesharecdn.com/311ringfayedringdoc1-180426033401/85/The-Ring-programming-language-version-1-5-4-book-Part-32-of-185-2-320.jpg)
The Ring programming language version 1.5.4 book - Part 32 of 185
- 1. Ring Documentation, Release 1.5.4 Func Test see "Message from the test function!" + nl Func Times nCount,F for x = 1 to nCount Call F() next Output: Message from the test function! Message from the test function! Message from the test function! Message from the test function! Message from the test function! 40.4 Anonymous and Nested Functions Anonymous Functions are functions without names that can be passed as parameters to other functions or stored in variables. Syntax: Func [Parameters] { [statements] } Example: test( func x,y { see "hello" + nl see "Sum : " + (x+y) + nl } ) new great { f1() } times(3, func { see "hello world" + nl } ) func test x call x(3,3) see "wow!" + nl func times n,x for t=1 to n call x() next Class great func f1 f2( func { see "Message from f1" + nl } ) func f2 x call x() Output: hello Sum : 6 40.4. Anonymous and Nested Functions 285
- 2. Ring Documentation, Release 1.5.4 wow! Message from f1 hello world hello world hello world Example: Func Main aList = [1,2,3,4] Map (aList , func x { return x*x } ) see aList aList = [4,9,14,25] Map(aList, :myfilter ) see aList aList = [11,12,13,14] Map (aList , func x { if x%2=0 return "even" else return "odd" ok }) see aList Func myfilter x if x = 9 return "True" else return "False" ok Func Map aList,cFunc for x in aList x = call cFunc(x) next Output: 1 4 9 16 False True False False odd even odd even 40.5 Equality of functions We can test if function = function or not using the ‘=’ or ‘!=’ operators 40.5. Equality of functions 286
- 3. Ring Documentation, Release 1.5.4 Example: f1 = func { see "hello" + nl } f2 = func { see "how are you?" + nl } f3 = f1 call f1() call f2() call f3() see (f1 = f2) + nl see (f2 = f3) + nl see (f1 = f3) + nl Output: hello how are you? hello 0 0 1 40.5. Equality of functions 287
- 4. CHAPTER FORTYONE REFLECTION AND META-PROGRAMMING Since the Ring programming language is a dynamic language, we can get answers about the program code and we can modify our code during the runtime. In this chapter we will learn about this and the available functions to use. 41.1 locals() Function We can get a list of variables names in the current scope using the locals() function. Syntax: locals() --> a list contains the variables names in the current scope Example: test("hello") func test cMsg see cMsg + nl x = 10 y = 20 z = 30 see locals() Output: hello cmsg x y z 41.2 globals() Function We can get a list of variables names in the global scope using the globals() function. Syntax: 288
- 5. Ring Documentation, Release 1.5.4 globals() --> a list contains variables names in the global scope Example: x=10 y=20 z=30 test() func test see "message from test()" + nl + "Global Variables:" + nl see globals() Output: message from test() Global Variables: x y z 41.3 functions() Function We can get a list of functions names written in the Ring language using the functions() function. Syntax: functions() --> a list contains functions names Example: see functions() func f1 see "f1" + nl func f2 see "f2" + nl func f3 see "f3" + nl Output: f1 f2 f3 41.4 cfunctions() Function We can get a list of functions names written in the C language using the cfunctions() function. Syntax: cfunctions() --> a list contains functions names Example: 41.3. functions() Function 289
- 6. Ring Documentation, Release 1.5.4 aList = cfunctions() See "Count : " + len(aList) + nl for x in aList see x + "()" + nl next Output: Count : 197 len() add() del() get() clock() ... Note: The complete list is removed from the previous output. 41.5 islocal() Function We can check if a variable is defined in the local scope or not using the islocal() function. Syntax: islocal(cVariableName) --> returns 1 if the variable is defined in the local scope returns 0 if the variable is not defined in the local scope Example: test() func test x=10 y=20 see islocal("x") + nl + islocal("y") + nl + islocal("z") + nl Output: 1 1 0 41.6 isglobal() Function We can check if a variable is defined in the global scope or not using the isglobal() function. Syntax: isglobal(cVariableName) --> returns 1 if the variable is defined in the global scope returns 0 if the variable is not defined in the global scope Example: 41.5. islocal() Function 290
- 7. Ring Documentation, Release 1.5.4 x=10 y=20 test() func test see isglobal("x") + nl + isglobal("y") + nl + isglobal("z") + nl Output: 1 1 0 41.7 isfunction() Function We can check if a Ring function is defined or not using the isfunction() function. Syntax: isfunction(cFunctionName) --> returns 1 if the Ring function is defined returns 0 if the Ring function is not defined Example: see isfunction("f1") + nl + isfunction("f2") + nl + isfunction("f3") + nl func f1 see "message from f1()" + nl func f2 see "message from f2()" + nl Output: 1 1 0 41.8 iscfunction() Function We can check if a C function is defined or not using the iscfunction() function. Syntax: iscfunction(cFunctionName) --> returns 1 if the C function is defined returns 0 if the C function is not defined Example: see iscfunction("len") + nl + iscfunction("add") + nl + iscfunction("test") + nl 41.7. isfunction() Function 291
- 8. Ring Documentation, Release 1.5.4 Output: 1 1 0 41.9 packages() Function We can get a list of packages names using the packages() function. Syntax: packages() --> a list contains packages names Example: See packages() Package Package1 Class class1 Func f1 Package Package2 Class class1 Func f1 Package Package3 Class class1 Func f1 Package Package4 Class class1 Func f1 Output: package1 package2 package3 package4 41.10 ispackage() Function We can check if a package is defined or not using the ispackage() function. Syntax: ispackage(cPackageName) --> returns 1 if the Package is defined returns 0 if the Package is not defined Example: See ispackage("package1") + nl + ispackage("package4") + nl + ispackage("package5") + nl + ispackage("package3") + nl 41.9. packages() Function 292
- 9. Ring Documentation, Release 1.5.4 Package Package1 Class class1 Func f1 Package Package2 Class class1 Func f1 Package Package3 Class class1 Func f1 Package Package4 Class class1 Func f1 Output: 1 1 0 1 41.11 classes() Function We can get a list of classes names using the classes() function. Syntax: classes() --> a list contains classes names Example: See classes() Class class1 Func f1 Class class2 Func f1 Class class3 Func f1 Output: class1 class2 class3 41.12 isclass() Function We can check if a class is defined or not using the isclass() function. Syntax: 41.11. classes() Function 293
- 10. Ring Documentation, Release 1.5.4 isclass(cClassName) --> returns 1 if the Class is defined returns 0 if the Class is not defined Example: see isclass("class4") + nl + isclass("class3") + nl + isclass("class2") + nl Class class1 func f1 class class2 func f1 class class3 func f1 Output: 0 1 1 41.13 packageclasses() Function We can get a list of classes names inside a package using the packageclasses() function. Syntax: packageclasses(cPackageName) --> a list contains classes names inside the package Example: see "classes in Package1" + nl see packageclasses("Package1") see "classes in Package2" + nl see packageclasses("Package2") Package Package1 Class class1 Func f1 Package Package2 Class class1 Func f1 Class class2 Func f1 Class class3 func f1 Output: classes in Package1 class1 classes in Package2 class1 41.13. packageclasses() Function 294