Syntax Flexibility
In this chapter we will learn about some options that are provided automatically by the Ring compiler for syntax flexibility.
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 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 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 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 commands 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 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.
Tip
Using LoadSyntax command is optional, See the (Automatic loading for syntax files) section.
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 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:
Hello How are you? Welcome to Ring one two three 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 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 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 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 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 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 { x = 1 / 0 catch see "catching error" + nl } Output:
if statement.. one for loop.. 12345678910 switch... one try catch... catching error Using ‘put’ and ‘get’ as ‘see’ and ‘give’
We can replace the ‘see’ keyword with the ‘put’ keyword.
Also we can replace the ‘give’ keyword with the ‘get’ keyword.
Example:
put "Hello World" + nl put "Enter Your Name ? " Get Name Put "Hello " + Name Using ‘case’ as ‘on’ in switch statements
We can replace the ‘on’ keyword with ‘case’ keyword in the switch statement.
Example (1) :
for x=1 to 10 switch x case 1 put "one" + nl case 2 put "two" + nl case 3 put "three" + nl else put "else" + nl end end Example (2) :
for x=1 to 10 { switch x { case 1 put "one" + nl case 2 put "two" + nl case 3 put "three" + nl else put "else" + nl } } Using ‘def’ as ‘func’ in functions/methods definition
We can use the ‘def’ keyword as the ‘func’ keyword to define functions and methods.
Example:
one() two() def one put "one" + nl def two put "two" + nl Using braces { } in Packages/Classes/Functions
Example:
load "stdlib.ring" import mypackage new myclass { myfunc() } package mypackage { class myclass { func myfunc { print("Hello, World!\n") } } } Using ‘break’/’continue’ keywords
Instead of using Exit/Loop commands we can use Break/Continue
Example:
for t=1 to 10 { if t=3 { continue elseif t=5 break } ? t } Output:
1 2 4 Using ‘end’ keyword after Packages/Classes/Functions
Example:
import mypackage new myclass { myfunc() } package mypackage class myclass def myfunc put "Hello, World!" end end end Using ‘function’/’endfunction’ keywords
Example:
one() two() three() function one ? :one endfunction function two ? :two endfunction function three ? :three endfunction Using ‘endif’/’endfor’/’endwhile’/’endswitch’/’endtry’ keywords
Example:
for t=1 to 10 if t=3 ? :three endif endfor Using ‘endpackage’/’endclass’/’endfunc’ keywords after Packages/Classes/Functions
Example:
import mypackage new myclass { myfunc() } package mypackage class myclass func myfunc see "welcome" + nl endfunc endclass endpackage Ignore new lines after keywords
Starting from Ring 1.8 the compiler will ignore new lines after keywords that expect tokens after it
Example:
see " Hello, World! " test() func #======================# Test #======================# ? " Hello from the Test function " Output:
Hello, World! Hello from the Test function Automatic loading for syntax files
Starting from Ring 1.18 we have better syntax flexibility
Support running source code files with any extension
Automatic loading for (ringsyntax.ring) file that exist in the current folder
For example in the the next screen shot
We have (ringsyntax.ring) that translate some of the Ring keywords to Arabic language
When we execute the file with Arabic name which means in English (hello.ring)
Ring will automatically execute (ringsyntax.ring) using Load Syntax command
Each Folder in the program could have it’s optional (ringsyntax.ring) file
We can mix styles in the same project
For Windows users, To use Arabic source code files with Ring, Set the language settings.
Enable/Disable Hash Comments
Starting from Ring 1.20 we have the next two commands supported by the Ring Scanner
EnableHashComments
DisableHashComments
Example:
DisableHashComments #define = 10 EnableHashComments # Just a comment DisableHashComments ? #define EnableHashComments # End of program