The Ring programming language version 1.6 book - Part 34 of 189

The Ring programming language version 1.6 book - Part 34 of 189

• 1.
  Ring Documentation, Release1.6 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 41.5 Equality of functions We can test if function = function or not using the ‘=’ or ‘!=’ operators 41.5. Equality of functions 303
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  Ring Documentation, Release1.6 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 41.5. Equality of functions 304
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  CHAPTER FORTYTWO REFLECTION AND META-PROGRAMMING Sincethe 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. • locals() • globals() • functions() • cfunctions() • islocal() • isglobal() • isfunction() • iscfunction() • packages() • ispackage() • classes() • isclass() • packageclasses() • ispackageclass() • classname() • objectid() • isobject() • attributes() • methods() • isattribute() • isprivateattribute() • ismethod() • isprivatemethod() • addattribute() • addmethod() 305
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  Ring Documentation, Release1.6 • getattribute() • setattribute() • mergemethods() • packagename() 42.1 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 42.2 globals() Function We can get a list of variables names in the global scope using the globals() function. Syntax: 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: 42.1. locals() Function 306
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  Ring Documentation, Release1.6 message from test() Global Variables: x y z 42.3 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 42.4 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: aList = cfunctions() See "Count : " + len(aList) + nl for x in aList see x + "()" + nl next Output: Count : 197 len() add() del() get() 42.3. functions() Function 307
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  Ring Documentation, Release1.6 clock() ... Note: The complete list is removed from the previous output. 42.5 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 42.6 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: x=10 y=20 test() func test see isglobal("x") + nl + isglobal("y") + nl + isglobal("z") + nl Output: 1 1 0 42.5. islocal() Function 308
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  Ring Documentation, Release1.6 42.7 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 42.8 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 Output: 1 1 0 42.9 packages() Function We can get a list of packages names using the packages() function. Syntax: packages() --> a list contains packages names 42.7. isfunction() Function 309
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  Ring Documentation, Release1.6 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 42.10 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 Package Package1 Class class1 Func f1 Package Package2 Class class1 Func f1 Package Package3 Class class1 Func f1 Package Package4 Class class1 Func f1 42.10. ispackage() Function 310
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  Ring Documentation, Release1.6 Output: 1 1 0 1 42.11 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 42.12 isclass() Function We can check if a class is defined or not using the isclass() function. Syntax: 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 42.11. classes() Function 311
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  Ring Documentation, Release1.6 Output: 0 1 1 42.13 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 class2 class3 42.14 ispackageclass() Function We can check if a class is defined inside package or not using the ispackageclass() function. Syntax: ispackageclass(cPackageName,cClassName) --> returns 1 if the Class is defined returns 0 if the Class is not defined Example: see ispackageclass("package1","class1") + nl + ispackageclass("package1","class2") + nl + ispackageclass("package2","class1") + nl + 42.13. packageclasses() Function 312