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**jbell** · 06-09-2011, 04:15 PM

Re: Alpha 5 XBasic Classes and Objects

Just as a matter of making this more clear, here is what I have currently:

A test class:

Code:

' This class will be used for file manipulation,
'	including saving the file to th file system and the sql database.
define class global cnsFile

	dim fileName as c
 	dim file as c

	' Function saveFile
	'
	' This function saves the file passed in to the file system
	' inserts a row to the database for that file.
	'
	' Passed: fileName
	'
	'
	' Returned:
	' 
	function saveFile as v(fileName)
		self.fileName = fileName;
		return self.fileName
	end function

	' Function saveSQL
	'
	' This function saves the file passed in to the SQL database
	' inserts a row to the database for that file.
	'
	' Passed:
	'
	'
	' Returned:
	' bol success - true or false based on save status 
	function saveSQL as v()
		'ui_msg_box("fileName",self.fileName)
	end function
end class

A test page that uses the class:

Code:

<!DOCTYPE html>
<html>
<head>
<meta name="generator" content="Alpha Five HTML Editor Version 10 Build 4345-3709">
<!-- must use in order to make XP Themes render -->
<meta HTTP-EQUIV="MSThemeCompatible" content="Yes" />
<meta http-equiv="X-UA-Compatible" content="IE=edge" />
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> 

<title></title>
</head>
<body>
<p>
<%a5
	a5w_include("cnsFile.txt")
	cnsFile.saveFile()
%>
</p>
</body></html>

After I publish this locally, this is the response I get in FireFox when I attempt to access the page:

500 Internal Server Error
"Script Error
Error:Script: /testjb.a5w line:19
cnsFile.saveFile()
Not found
cnsFile not found."

**Lenny Forziati** · 06-09-2011, 04:54 PM

Re: Alpha 5 XBasic Classes and Objects

You have several problems:

Your class is not static and you are trying to use it without an instance.
There is no return in Xbasic. You wouldn't want to return a value on a void function anyway.
You are calling the saveFile() method with no arguments, but it requires a single argument to be passed.

**Lenny Forziati** · 06-09-2011, 04:59 PM

Re: Alpha 5 XBasic Classes and Objects

Also ui_msg_box(), which you are presumably using just for testing anyway, cannot be used in an A5W page. During development/testing, it is often easier to use a script in the development environment, where ui_msg_box() and debug() can be a tremendous help.

Save the following as an Xbasic script to see it in action

Code:

'define class global cnsFile
define class cnsFile

	dim fileName as c
 	dim file as c

	' Function saveFile
	'
	' This function saves the file passed in to the file system
	' inserts a row to the database for that file.
	'
	' Passed: fileName
	'
	'
	' Returned:
	' 
	function saveFile as v(fileName)
		self.fileName = fileName;
		'return self.fileName
	end function

	' Function saveSQL
	'
	' This function saves the file passed in to the SQL database
	' inserts a row to the database for that file.
	'
	' Passed:
	'
	'
	' Returned:
	' bol success - true or false based on save status 
	function saveSQL as v()
		ui_msg_box("fileName",self.fileName)
	end function
end class


dim cnsFileInstance as cnsFile
cnsFileInstance.saveFile("ThisIsMyTestFile.txt")
cnsFileInstance.saveSQL()

**aburningflame** · 06-10-2011, 09:34 AM

Re: Alpha 5 XBasic Classes and Objects

Originally posted by Lenny Forziati View Post

You have several problems:

Your class is not static and you are trying to use it without an instance.
There is no return in Xbasic. You wouldn't want to return a value on a void function anyway.
You are calling the saveFile() method with no arguments, but it requires a single argument to be passed.

How come you didnt give him the solution for #2?

ANyways - I believe the return in xbasic is assigning your return value to your function.
SO

function saveFile as v(fileName)
self.fileName = fileName;
return self.fileName
end function

Becomes

function saveFile as v(fileName)
self.fileName = fileName;
saveFile=self.fileName
end function

Your best bet is to return pointers

Code:

function saveFile as P(fileName [b]as C[/b])
               dim ret as P
               dim ret.error as L
               dim ret.errorText as C
		self.fileName = fileName;
		if (code to save file)==.f. then
                        ret.error=.t.
                        ret.errorText="Could not save file"
                end if
                [b]saveFile=ret[/b]
	end function

Code:

      dim ret as P=obj.saveFile("c:/test.txt")
      if ret.error==.t. then
            ?ret.errorText <<if this is on an a5w page - this line prints the error text to the page
      end if

**Lenny Forziati** · 06-10-2011, 11:23 AM

Re: Alpha 5 XBasic Classes and Objects

Originally posted by aburningflame View Post

How come you didnt give him the solution for #2?

I knew someone else would be along to fill in that blank shortly

Originally posted by aburningflame View Post

ANyways - I believe the return in xbasic is assigning your return value to your function.

Correct

Originally posted by aburningflame View Post

SO

function saveFile as v(fileName)
self.fileName = fileName;
return self.fileName
end function

Becomes

function saveFile as v(fileName)
self.fileName = fileName;
saveFile=self.fileName
end function

While this won't cause an error, it also won't return a value because the function definition sets the return type to v(oid). To get a value returned, it would need to be

Code:

function saveFile as [B]c[/B](fileName)
		self.fileName = fileName;
		saveFile=self.fileName
end function

Originally posted by aburningflame View Post

Your best bet is to return pointers

<sample code snipped>

If you use the pattern of returning a pointer with detailed error information regulalry, you may be interested in using a CallResult. This is the same class used in Alpha's internal objects, and it takes care of resetting error codes and text for you when you set the Error or Success properties:

Code:

dim x as CallResult
?x
= Canceled = .F.
Code = 0
Error = .F.
NativeCode = 0
NativeText = ""
ReturnDataValue = <No data returned>
Success = .T.
Text = "Success"

x.Error = .t.
?x
= Canceled = .F.
Code = -1
Error = .T.
NativeCode = 0
NativeText = ""
ReturnDataValue = <No data returned>
Success = .F.
Text = "Unknown error"

x.Success = .t.
?x
= Canceled = .F.
Code = 0
Error = .F.
NativeCode = 0
NativeText = ""
ReturnDataValue = <No data returned>
Success = .T.
Text = "Success"

**aburningflame** · 06-10-2011, 11:30 AM

Re: Alpha 5 XBasic Classes and Objects

We regularly return a pointer from our functions - however the callresult is too detailed for our needs.

dim ret as P
dim ret.error as L
dim ret.errorText as C

Is usually enough to suit our needs.

Your other option is to create a custom class with all the options you would need to return - and return an object of that class. I havent used OOP techniques in Alpha - although I am very familiar with it in c#,php,java.

Havent really seen the opportunity to use classes/objects - but - this should get you on your way.

**jbell** · 06-10-2011, 12:07 PM

Re: Alpha 5 XBasic Classes and Objects

Lenny Forziati and aburningflame:

Thank you very much for all of the input that you have provided. I understand the xBasic class/object process much better now than I did. I hope this thread is as useful to anyone searching on the subject as it has been for me.

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Alpha 5 XBasic Classes and Objects

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