The Ring programming language version 1.10 book - Part 17 of 212

Ring Documentation, Release 1.10
Trace Function Name : mytrace()
Trace Event : Before C Function
Line Number : 9
File Name : test1.ring
Function Name : ismethod
Method or Function : Function
==========================================
====== The Trace function is Active ======
Trace Event : After C Function
Line Number : 9
==========================================
Trace Event : New Function
Line Number : 9
Function Name : mymethod
Method or Function : Method
==========================================
Trace Event : New Line
Line Number : 44
Function Name : mymethod
Method or Function : Method
==========================================
Message from mymethod
Trace Event : Return
Line Number : 9
Function Name :
Method or Function : Command
==========================================
Line Number : 9
==========================================
Line Number : 9
==========================================
9.14. Ring VM - Tracing Functions 128

Line Number : 9
==========================================
Line Number : 9
==========================================
Trace Event : New Line
Line Number : 11
Function Name :
Method or Function : Command
==========================================
9.15 Trace Library and Interactive Debugger
Ring 1.5 comes with the Trace Library and the Interactive Debugger
Using this library we can trace events, execute programs line by line, open the Interactive Debugger when an error
happens or at breakpoints.
Example:
The next example uses a Breakpoint to open the Interactive Debugger!
load "tracelib.ring"
test1()
func test1
x = 10
see :test1 + nl
t = 12
BreakPoint()
see "After breakpoint!" +nl
see "t = " + t + nl
see "End of program!" + nl
Screen Shots:
We have the Interactive Debugger at the Breakpoint!
9.15. Trace Library and Interactive Debugger 129

We can print the variables values
We can change the variables values then continue execution
We can run the Interactive Debugger in the Output Window
9.15. Trace Library and Interactive Debugger 130

9.16 More Syntax Flexibility
• 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()
}
9.16. More Syntax Flexibility 131

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
9.17 Type Hints Library
Ring 1.5 comes with the Type Hints library
Using this library we can add the type information to the source code which will be very useful for tools like
• Code Editors
• Static-Analysis
Example:
load "typehints.ring"
see sum(3,4) + nl ;
see sayHello("Mahmoud");
int func sum(int x,int y) {
return x+y ;
}
string func sayHello(string name) {
return "Hello " + name ;
}
The library is very powerful and support the User types (Classes) automatically!
Example:
import mypackage
test() { main([:one,:two,:three]) }
9.17. Type Hints Library 132

myclass func test() {
see "Testing User Types!" + nl
return new myclass
}
package mypackage {
public class myclass {
public static void func main(list args) {
see "welcome" + nl
see args
}
}
}
Also You can use the types inside the code (not only the function prototype)
Example:
int sum = sum(3,4)
string msg = sayHello("Mahmoud")
see "Sum = " + sum + nl + msg + nl
int func sum(int x,int y) {
return x+y ;
}
string func sayHello(string name) {
return "Hello " + name ;
}
Rules:
• To use the types in the function prototype, You must use ‘(‘ and ‘)’ around parameters
• To use the types in the function code, You must set the variable value (Assignment).
Note: Ring is a dynamic language, No type checking will be done by the compiler.
9.18 Better Quality
Based on Ring usage every day in practical projects
Ring 1.5 is more stable and more productive!
We are adding features based on clear vision and practical needs.
Also the documentation is better.
9.19 What is new in Ring 1.5.1?
• Better Documentation
9.18. Better Quality 133

• StdLib - Factorial() function update
• RingVM - Better code for clearing the stack in the Class Region.
• Sample : 3D Cube (OpenGL) + Texture Image using GameLib (RingAllegro)
Source Code:
load "gamelib.ring"
load "opengl21lib.ring"
func main
new GraphicsApp {
start()
}
class GraphicsApp from GraphicsAppBase
TITLE = "Ring Cube"
bitmap texture
xrot = 0.0
yrot = 0.0
zrot = 0.0
func loadresources
bitmap = al_load_bitmap("ring.bmp")
texture = al_get_opengl_texture(bitmap)
func destroyResources
al_destroy_bitmap(bitmap)
func drawScene
w = 800 h = 600
ratio = w / h
glViewport(0, 0, w, h)
glMatrixMode(GL_PROJECTION)
glLoadIdentity()
gluPerspective(45,ratio,1,100)
glMatrixMode(GL_MODELVIEW)
glLoadIdentity()
glEnable(GL_TEXTURE_2D)
glShadeModel(GL_SMOOTH)
glClearColor(0.0, 0.0, 0.0, 0.5)
glClearDepth(1.0)
glEnable(GL_DEPTH_TEST)
glEnable(GL_CULL_FACE)
glDepthFunc(GL_LEQUAL)
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST)
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
9.19. What is new in Ring 1.5.1? 134

glLoadIdentity();
glTranslatef(0.0,0.0,-5.0);
glRotatef(xrot,1.0,0.0,0.0);
glRotatef(yrot,0.0,1.0,0.0);
glRotatef(zrot,0.0,0.0,1.0);
glBindTexture(GL_TEXTURE_2D, texture)
glBegin(GL_QUADS)
// Front Face
glTexCoord2f(0.0, 0.0) glVertex3f(-1.0, -1.0, 1.0)
glTexCoord2f(1.0, 0.0) glVertex3f( 1.0, -1.0, 1.0)
glTexCoord2f(1.0, 1.0) glVertex3f( 1.0, 1.0, 1.0)
glTexCoord2f(0.0, 1.0) glVertex3f(-1.0, 1.0, 1.0)
// Back Face
glTexCoord2f(1.0, 0.0) glVertex3f(-1.0, -1.0, -1.0)
glTexCoord2f(1.0, 1.0) glVertex3f(-1.0, 1.0, -1.0)
glTexCoord2f(0.0, 1.0) glVertex3f( 1.0, 1.0, -1.0)
glTexCoord2f(0.0, 0.0) glVertex3f( 1.0, -1.0, -1.0)
// Top Face
// Bottom Face
// Right face
// Left Face
glEnd()
xrot += 0.3
yrot += 0.2
zrot += 0.4
class GraphicsAppBase
display event_queue ev timeout
timer redraw = true
FPS = 60
SCREEN_W = 800
SCREEN_H = 600
KEY_UP = 1

KEY_DOWN = 2
KEY_LEFT = 3
KEY_RIGHT = 4
Key = [false,false,false,false]
TITLE = "Graphics Application"
func start
SetUp()
loadResources()
eventsLoop()
destroy()
func setup
al_init()
al_init_image_addon()
al_set_new_display_flags(ALLEGRO_OPENGL)
display = al_create_display(SCREEN_W,SCREEN_H)
al_set_Window_title(display,TITLE)
al_clear_to_color(al_map_rgb(0,0,0))
event_queue = al_create_event_queue()
al_register_event_source(event_queue,
al_get_display_event_source(display))
ev = al_new_allegro_event()
timeout = al_new_allegro_timeout()
al_init_timeout(timeout, 0.06)
timer = al_create_timer(1.0 / FPS)
al_get_timer_event_source(timer))
al_start_timer(timer)
al_install_mouse()
al_get_mouse_event_source())
al_install_keyboard()
al_get_keyboard_event_source())
func eventsLoop
while true
al_wait_for_event_until(event_queue, ev, timeout)
switch al_get_allegro_event_type(ev)
on ALLEGRO_EVENT_DISPLAY_CLOSE
exit
on ALLEGRO_EVENT_TIMER
redraw = true
on ALLEGRO_EVENT_MOUSE_AXES
mouse_x = al_get_allegro_event_mouse_x(ev)
mouse_y = al_get_allegro_event_mouse_y(ev)
on ALLEGRO_EVENT_MOUSE_ENTER_DISPLAY
mouse_x = al_get_allegro_event_mouse_x(ev)
mouse_y = al_get_allegro_event_mouse_y(ev)
on ALLEGRO_EVENT_MOUSE_BUTTON_UP
exit
on ALLEGRO_EVENT_KEY_DOWN

switch al_get_allegro_event_keyboard_keycode(ev)
on ALLEGRO_KEY_UP
key[KEY_UP] = true
on ALLEGRO_KEY_DOWN
key[KEY_DOWN] = true
on ALLEGRO_KEY_LEFT
key[KEY_LEFT] = true
on ALLEGRO_KEY_RIGHT
key[KEY_RIGHT] = true
off
on ALLEGRO_EVENT_KEY_UP
switch al_get_allegro_event_keyboard_keycode(ev)
on ALLEGRO_KEY_UP
key[KEY_UP] = false
on ALLEGRO_KEY_DOWN
key[KEY_DOWN] = false
on ALLEGRO_KEY_LEFT
key[KEY_LEFT] = false
on ALLEGRO_KEY_RIGHT
key[KEY_RIGHT] = false
on ALLEGRO_KEY_ESCAPE
exit
off
off
if redraw and al_is_event_queue_empty(event_queue)
redraw = false
drawScene()
al_flip_display()
ok
callgc()
end
func destroy
destroyResources()
al_destroy_timer(timer)
al_destroy_allegro_event(ev)
al_destroy_allegro_timeout(timeout)
al_destroy_event_queue(event_queue)
al_destroy_display(display)
func loadresources
func drawScene
func destroyResources
Screen Shot:

The Ring programming language version 1.10 book - Part 17 of 212

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The Ring programming language version 1.10 book - Part 17 of 212