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.

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 ‘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 ‘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