Syntax Flexibility

Ring

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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 replacew 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 "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
        }
}

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

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