The Ring programming language version 1.3 book - Part 30 of 88

1. Ring Documentation, Release 1.3
start
Hello
end
start
end
41.8 BraceExprEval Method
The next example demonstrates how to use the “BraceExprEval” method to get expressions in Natural code.
Example:
new natural {
create 5
}
class natural
create=0
lkeyword = false
func braceexpreval r
if lkeyword lkeyword=false return ok
see "expr eval" + nl
see "type: " + type(r) see nl
see "value : " see r see nl
func getcreate
lkeyword = true
see "create" + nl
Output:
create
expr eval
type: NUMBER
value : 5
41.9 Real Natural Code
The next example is a more advanced example
# Natural Code
new program {
Accept 2 numbers then print the sum
}
# Natural Code Implementation
class program
# Keywords
Accept=0 numbers=0 then=0 print=0 the=0 sum=0
# Execution
func braceexpreval x
value = x
func getnumbers
for x=1 to value
see "Enter Number ("+x+") :" give nNumber
41.8. BraceExprEval Method 268

2. Ring Documentation, Release 1.3
aNumbers + nNumber
next
func getsum
nSUm = 0
for x in aNumbers nSum+= x next
see "The Sum : " + nSum
private
value=0 aNumbers=[]
Output:
Enter Number (1) :3
Enter Number (2) :4
The Sum : 7
41.10 BraceError() Method
The next examples demonstrates how to use the “BraceError” method to handle errors when accessing the object using
braces {}.
Example:
func main
o1 = new point {
x=10 y=20 z=30
TEST
SEE test
}
class point x y z
func braceerror
see "Handle Error!" + nl
SEE "Message :" + cCatchError + nl
if ( left(cCatchError,11) = "Error (R24)" ) and not isattribute(self,"test")
see "add attribute" + nl
addattribute(self,"test")
test = 10
ok
see "done" + nl
return
Output:
Handle Error!
Message :Error (R24) : Using uninitialized variable : test
add attribute
done
10
Example:
new point {
x=10 y=20 z=30
test()
see "mmm..." + NL
}
41.10. BraceError() Method 269

3. Ring Documentation, Release 1.3
class point x y z
func braceerror
see "Handle Error!" + nl
see "Message :" + cCatchError + nl
see self
see "Done" + NL
Output:
Handle Error!
Message :Error (R3) : Calling Function without definition !: test
x: 10.000000
y: 20.000000
z: 30.000000
Done
mmm...
41.11 Clean Natural Code
Instead of typing the literal as “literal” we can accept the words directly.
Example:
The next example accept hello world instead of “hello world”
But this example uses braceend() to check the end of the instruction
This means that this class process only one natural statement that end with literal.
ChangeRingKeyword and _and
New App
{
I want window and the window title is hello world
}
Class App
# Attributes for the instruction I want window
i want window
nIwantwindow = 0
# Attributes for the instruction Window title
# Here we don't define the window attribute again
title is
nWindowTitle = 0
# Keywords to ignore, just give them any value
the=0 and=0
# Data
literal = ""
ChangeRingKeyword _and and
func geti
if nIwantwindow = 0
nIwantwindow++
ok
func getwant
41.11. Clean Natural Code 270

4. Ring Documentation, Release 1.3
if nIwantwindow = 1
nIwantwindow++
ok
func getwindow
if nIwantwindow = 2
nIwantwindow= 0
see "Instruction : I want window" + nl
ok
if nWindowTitle = 0
nWindowTitle++
ok
func gettitle
if nWindowTitle = 1
nWindowTitle=2
ok
func getis
if nWindowTitle = 2
nWindowTitle=3
ok
func braceend
if nWindowTitle = 3
see "Instruction : Window Title = " + literal + nl
nWindowTitle = 0
ok
func braceerror
c= substr(cCatchError,":")
while c > 0
c= substr(cCatchError,":")
cCatchError=substr(cCatchError,c+1)
end
literal += substr(cCatchError,1)
41.11. Clean Natural Code 271

5. CHAPTER
FORTYTWO
WEB DEVELOPMENT (CGI LIBRARY)
In this chapter we will learn about developing Web applications using a CGI Library written in the Ring language.
42.1 Configure the Apache web server
We can use Ring with any web server that support CGI. In this section we will learn about using Ring with the Apache
HTTP Server.
You can download Apache from : http://httpd.apache.org/
Or you can get it included with other projects like
XAMPP : https://www.apachefriends.org/download.html
Install then open the file:
xamppapacheconfhttpd.conf
search for
<Directory />
Then after it add
Options FollowSymLinks +ExecCGI
So we have
<Directory />
Options FollowSymLinks +ExecCGI
Search for the next line and be sure that it’s not commented
LoadModule cgi_module modules/mod_cgi.so
Search for : AddHandler cgi-script
Then add ”.ring” to the supported cgi extensions
Example
AddHandler cgi-script .cgi .ring
Example
AddHandler cgi-script .cgi .pl .asp .ring
272

6. Ring Documentation, Release 1.3
Run/Start the server
Create your web applications in a directory supported by the web server.
Example:
Apache2.2htdocsmywebapplicationfolder
Example:
xampphtdocsmywebapplicationfolder
Inside the source code file (*.ring), Add this line
#!c:ringbinring.exe -cgi
Note: Change the previous line based on the path to ring.exe in your machine
42.2 Ring CGI Hello World Program
The next program is the Hello World program
#!c:ringbinring.exe -cgi
See "content-type : text/html" +nl+nl+
"Hello World!" + nl
42.3 Hello World Program using the Web Library
We can use the web library to write CGI Web applications quickly
Example (1) :
#!c:ringbinring.exe -cgi
Load "weblib.ring"
Import System.Web
New Page
{
Text("Hello World!")
}
Example (2) :
#!c:ringbinring.exe -cgi
Load "weblib.ring"
Import System.Web
WebPage()
{
Text("Hello World!")
}
42.2. Ring CGI Hello World Program 273

7. Ring Documentation, Release 1.3
Tip: the difference between ex. 1 and ex. 2 is using WebPage() function to return the page object instead of creating
the object using new statement.
42.4 Web Library Features
The next features are provided by the Web library to quickly create web applications.
• Generate HTML pages using functions
• Generate HTML pages using objects
• HTTP Get
• HTTP Post
• Files Upload
• URL Encode
• Templates
• CRUD MVC Sample
• Users Logic & Registration Sample
42.5 HTTP Get Example
The Page User Interface
#!c:ringbinring.exe -cgi
Load "weblib.ring"
Import System.Web
New Page
{
Title = "Test HTTP Get"
divstart([ :style = StyleSizeFull() ] )
boxstart()
text( "Test HTTP GET" )
newline()
boxend()
divstart([ :style = Styledivcenter("600px","550px") +
StyleGradient(21) ])
divstart([:style = stylefloatleft() + stylesize("100px","100%") +
stylecolor("black") + stylegradient(58)])
formstart("ex5.ring")
tablestart([ :style = stylesize("65%","90%") +
stylemarginleft("35%") +
stylemargintop("30%") ])
rowstart([])
cellstart([])
text ( "Name : " )
cellend()
cellstart([])
cTextboxStyle = StyleMarginLeft("5%") +
StyleWidth("250px") +
StyleColor("black") +
42.4. Web Library Features 274

8. Ring Documentation, Release 1.3
StyleBackColor("white")
textbox([ :name = "Name", :style = cTextboxStyle ] )
cellend()
rowend()
rowstart([])
cellstart([])
text ( "Address : " )
cellend()
cellstart([])
textbox([ :name = "Address", :style = cTextboxStyle] )
cellend()
rowend()
rowstart([])
cellstart([])
text ( "Phone : " )
cellend()
cellstart([])
textbox([ :name = "Phone", :style = cTextboxStyle ])
cellend()
rowend()
rowstart([])
cellstart([])
text ( "Age : " )
cellend()
cellstart([])
textbox([ :name = "Age", :style = cTextboxStyle ])
cellend()
rowend()
rowstart([])
cellstart([])
text ( "City: " )
cellend()
cellstart([])
listbox([ :name = "City", :items = ["Cairo","Riyadh","Jeddah"],
:style = stylemarginleft("5%") + stylewidth("400px") ] )
cellend()
rowend()
rowstart([])
cellstart([])
text ( "Country : " )
cellend()
cellstart([])
combobox([ :name = "Country",
:items = ["Egypt","Saudi Arabia","USA"],
:style = stylemarginleft("5%") +
stylewidth("400px")+
stylecolor("black")+
stylebackcolor("white")+
stylefontsize("14px") ])
cellend()
rowend()
rowstart([])
cellstart([])
text ( "Note : " )
cellend()
cellstart([])
editbox([ :name = "Notes",
:style = stylemarginleft("5%") +
42.5. HTTP Get Example 275

9. Ring Documentation, Release 1.3
stylesize("400px","100px")+
stylecolor("black")+
stylebackcolor("white") ,
:value = "write comments here..." ] )
cellend()
rowend()
rowstart([])
cellstart([])
cellend()
cellstart([])
submit([ :value = "Send" , :Style = stylemarginleft("5%") ])
cellend()
rowend()
tableend()
formend()
divend()
divend()
divend()
}
Screen Shot:
42.5. HTTP Get Example 276

10. Ring Documentation, Release 1.3
The Response
#!c:ringbinring.exe -cgi
Load "weblib.ring"
Import System.Web
New Page
{
divstart([ :style = styledivcenter("800px","500px") ])
boxstart()
text ( "HTTP GET Response" ) newline()
boxend()
divstart([ :style = stylefloatleft()+stylewidth("10%")+
42.5. HTTP Get Example 277