The Ring programming language version 1.5.3 book - Part 84 of 184
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This document provides examples of syntax flexibility options in Ring, including: 1) Changing language keywords and operators using ChangeRingKeyword and ChangeRingOperator commands. 2) Loading syntax files using LoadSyntax to apply groups of keyword/operator changes. 3) Optional syntax elements like parentheses in functions, semicolons, and variable naming conventions. 4) Using 'elseif', 'else', and 'end' keywords interchangeably in control structures, and optionally using braces.
The Ring programming language version 1.5.3 book - Part 84 of 184
- 1. Ring Documentation, Release 1.5.3 61.2 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: 61.2. Example about Sharing Names between Functions and Methods 705
- 2. Ring Documentation, Release 1.5.3 ======================================== 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 ======================================== 61.3 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() 61.3. Calling a function sharing the name with a method in the current class 706
- 3. Ring Documentation, Release 1.5.3 func f3 see "f3 method" + nl class local Output: ======================================== test method f1 function f2 function f3 method f3 function ======================================== 61.3. Calling a function sharing the name with a method in the current class 707
- 4. CHAPTER SIXTYTWO SYNTAX FLEXIBILITY In this chapter we will learn about some options that are provided automatically by the Ring compiler for syntax flexibility. 62.1 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 see print 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 708
- 5. Ring Documentation, Release 1.5.3 x-- endwhile test() function test print "message from test" + nl ChangeRingKeyword function func ChangeRingKeyword print see ChangeRingKeyword endif ok ChangeRingKeyword endfor next ChangeRingKeyword endwhile end 62.2 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 62.2. Change Language Operators 709
- 6. Ring Documentation, Release 1.5.3 62.3 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 see print ChangeRingKeyword ok endif ChangeRingKeyword next endfor ChangeRingKeyword end endwhile File : StyleBasicOff.ring ChangeRingKeyword print see 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 62.3. Load Syntax Files 710
- 7. Ring Documentation, Release 1.5.3 translation to other languages like Arabic, French and so on. Tip: The effect of LoadSyntax command is related to the current source code file only. 62.4 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 62.5 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: 62.4. Using “()” around the function parameters 711
- 8. Ring Documentation, Release 1.5.3 Hello How are you? Welcome to Ring one two three 62.6 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 62.7 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 62.6. Using $ and @ in the start of the variable name 712
- 9. Ring Documentation, Release 1.5.3 62.8 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 62.9 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 62.8. Using the ‘else’ keyword as ‘other’ in switch statement 713
- 10. Ring Documentation, Release 1.5.3 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 62.10 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 { 62.10. Using braces to start and end different control structures 714