The Ring programming language version 1.2 book - Part 54 of 84

1. Ring Documentation, Release 1.2
func f3
see "f3 method" + nl
class local
Output:
========================================
test method
f1 function
f2 function
f3 method
f3 function
========================================
51.3. Calling a function sharing the name with a method in the current class 510

2. CHAPTER
FIFTYTWO
SYNTAX FLEXIBILITY
In this chapter we will learn about some options that are provided automatically by the Ring compiler for syntax
flexibility.
52.1 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
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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
52.2 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
52.2. Change Language Operators 512

4. Ring Documentation, Release 1.2
52.3 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
52.3. Load Syntax Files 513

5. Ring Documentation, Release 1.2
translation to other languages like Arabic, French and so on.
52.4 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
52.5 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:
Hello
How are you?
Welcome to Ring
52.4. Using “()” around the function parameters 514

6. Ring Documentation, Release 1.2
one
two
three
52.6 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
52.7 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
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52.8 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
52.9 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
52.8. Using the ‘else’ keyword as ‘other’ in switch statement 516

8. Ring Documentation, Release 1.2
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
52.10 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 {
52.10. Using braces to start and end different control structures 517

9. Ring Documentation, Release 1.2
x = 1 / 0
catch
see "catching error" + nl
}
Output:
if statement..
one
for loop..
12345678910
switch...
one
try catch...
catching error
52.11 Using ‘put’ and ‘get’ as ‘see’ and ‘give’
We can replace the ‘see’ keyword with the ‘put’ keyword.
Also we can replacew the ‘give’ keyword with the ‘get’ keyword.
Example:
put "Hello World" + nl
put "Enter Your Name ? " Get Name
Put "Hello " + Name
52.12 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 "thre" + 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 "thre" + nl
else put "else" + nl
}
}
52.11. Using ‘put’ and ‘get’ as ‘see’ and ‘give’ 518

10. Ring Documentation, Release 1.2
52.13 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
52.13. Using ‘def’ as ‘func’ in functions/methods definition 519