Classes and Methods

[Charles Pegge]

The following examples need the latest Oxygen compile download, (relaxing some requirements for empty brackets)


[code=thinbasic]


'CLASSES AND METHODS
'

uses "oxygen","file"
dim p0,p1 as long, src as string
dim dd(100) as double

src = "

class stat
method sum() as double
method average() as double
/
da(100) as double
dn as long
end class

'--------------
methods of stat
'==============

method sum() as double
dim i
for i = 1 to this.dn
method += this.da(i)
next
end method

method average() as double
method = this.sum / this.dn
end method

end methods

'====
'TEST
'====

dim s as stat

s.da=>2,4,6,8,10,12,14,16,18
s.dn=9
print `Sum: ` str(s.sum) ` Average: ` str s.average

"

o2_basic src

'msgbox 0, o2_view "o2h "+src

if len(o2_error) then
msgbox 0, o2_error : stop
end if

o2_exec



[/code]

[Charles Pegge]

Classes are a specialised form of TYPE which references a table of functions (or methods as they are known),
as well as data elements.

Each method for the class is defined in the methods block, which, under normal circumstances provides a cloak of invisibilty to the rest of the program. The methods can only be used by an object which belongs to the class.


[code=thinbasic]


'CLASSES AND METHODS
'

uses "oxygen","file"
dim p0,p1 as long, src as string
dim dd(100) as double

src = "

class string_stack
method push(s as string)
method pop() as string
/
buf as string
enb as long
le as long
end class

methods of string_stack

method push(s as string)
dim as long lb,ls,le
lb=len this.buf
ls=len s
'
'EXTEND STRINH BUFFER IF NEEDED
'
le=this.enb+ls+100
if le>lb then
this.buf+=space ls+1000
end if
'
'STORE STRING
'
mid(this.buf,this.enb+1)=s
'
'STORE STRING LENGTH
'
this.enb+=ls
dim as long p, a at p
p=*this.buf + this.enb
a=ls
this.enb+=4
end method

method pop() as string
'
'GET STRING LENGTH AND STRING INDEX
'
this.enb-=4
dim as long p, le at p
p=*this.buf + this.enb
this.enb-=le
'
'EXTRACT STRING
'
method=mid this.buf,this.enb+1,le
end method

end methods

'====
'TEST
'====

dim s as string_stack

s.push `abc` : s.push `defg` : s.push `hi`
print s.pop + `-` s.pop + `-` s.pop

terminate

"

o2_basic src

'msgbox 0, o2_view "o2h "+src

if len(o2_error) then
msgbox 0, o2_error : stop
end if

o2_exec


[/code]

[jcfuller]

Charles,
Has this been implemented in the download from yesterday?
I get nesting errors on both class examples

James

[jcfuller]

Never mind I found the update from today and all is well.

James

[Charles Pegge]

Hi James,

I'll be putting quite a few changes through over the next few weeks, as the examples expose new issues. Fortunately its a very small download.

Charles

[Charles Pegge]

This is a stub program, with an Opengl flavour, showing how a surface might be created from a list of points, each of which contain location,normal,color and texture mapping vectors which themselves contain various scalars: x y z r g b a.

The overall surface has stub methods for appending points, rendering and clearing its points list.

The surface object, which may contain any number of points, also has its own set of vectors for material: diffuse, specula and shininess, describing the way in which the surface interacts with light.

Quite a lot to squeeze into a few lines


[code=thinbasic]


'CLASSES AND MULTIPLE INHERITANCE

uses "oxygen","file"

dim src as string

src = "

class color_rgba
r as byte
g as byte
b as byte
a as byte
=
rgba as long
end class


class vector_2d
x as single
y as single
end class


class vector_3d
x as single
y as single
z as single
end class


#view

class point
vector_3d,
color_rgba,
normal as vector_3d
texmap as vector_2d
end class

class surface
method append(byval pt as long)
method clear()
method render()
/
list as string
po as long
le as long
mat_diffuse as color_rgba
mat_specular as color_rgba
mat_shininess as single
end class
#endv
methods of surface

method append(byval pt as long)
dim p,q as long
'
'CHECK BUFFER SPACE
'
p=this.po + sizeof point
if (p>=this.le) then
this.list+=space 2000
p=*this.list-4
this.le=*p
end if
'
'COPY IN
'
q=*this.list + this.po
copyn q, pt, sizeof point
this.po+=sizeof point
end method


method clear()
this.po=0
this.le=0
this.list=``
end method

method render()
'...
end method

end methods


'====
'TEST
'====

dim pt as point
dim sf as surface

sf.append &pt
sf.render
sf.clear
print `ok`
'
terminate

"

o2_basic src

msgbox 0, o2_len+$cr+o2_prep "o2h "+src

if len(o2_error) then msgbox 0, o2_error : stop

o2_exec


[/code]

[largo_winch]

hello charles, your examples in post #1 and post #2 don't run here (string stack). problems are word: "this.dn" (#1) and word "s.pop" (#2)

' Empty GUI script created on 12-01-2011 17:04:09 by  (ThinAIR)

'CLASSES AND METHODS
'

Uses "oxygen","file"
Dim p0,p1 As Long, src As String
Dim dd(100) As Double

src = "

CLASS string_stack
METHOD Push(s As String)
METHOD Pop() As String
/
buf As String
enb As Long
le As Long
End CLASS

methods of string_stack

METHOD Push(s As String)
Dim As Long lb,ls,le
lb=Len THIS.buf
ls=Len s
'
'EXTEND STRINH BUFFER IF NEEDED
'
le=THIS.enb+ls+100
If le>lb Then
THIS.buf+=space ls+1000
End If
'
'STORE STRING
'
mid(THIS.buf,THIS.enb+1)=s
'
'STORE STRING LENGTH
'
THIS.enb+=ls
Dim As Long p, a At p
p=*THIS.buf + THIS.enb
a=ls
THIS.enb+=4
End METHOD

METHOD Pop() As String
'
'GET STRING LENGTH AND STRING INDEX
'
THIS.enb-=4
Dim As Long p, le At p
p=*THIS.buf + THIS.enb
THIS.enb-=le
'
'EXTRACT STRING
'
METHOD=mid THIS.buf,THIS.enb+1,le
End METHOD

End methods

'====
'TEST
'====

Dim s As string_stack

s.Push `abc` : s.Push `defg` : s.Push `HI`
Print s.Pop + `-` s.Pop + `-` s.Pop

terminate

"

O2_BASIC src

'msgbox 0, o2_view "o2h "+src

If Len(O2_ERROR) Then
MsgBox 0, O2_ERROR : Stop
End If

O2_EXEC

bye, largo

[Charles Pegge]

Hi Largo,

This is an ancient example. Suffering from multiple version syndrome, I feel like Dr Who

I have recoded this idea from scratch. I hope it works on your current version.

uses "oxygen"


dim as string src


src="


'================
class StringStack
'================


  string buf
  sys pb
  sys lb


  method push(string s)
  '====================
    sys ls=len s
    sys pn=pb+ls+4
    '
    'ELASTIC BUFFER
    '
    if pn>lb then
      buf+=nuls 4000
      lb=len buf
    end if
    '
    'APPEND STRING AND ITS LENGTH
    '
       method push(string s)  '====================
    sys ls=len s
    sys pn=pb+ls+4
    '
    'ELASTIC BUFFER
    '
    if pn>lb then
      buf+=nuls 4000
      lb=len buf
    end if
    '
    'APPEND STRING AND ITS LENGTH
    '
    mid (buf,pb+1)=s 'APPEND STRING
    pb+=ls
    sys p=*buf + pb
    *p=ls 'PATCH IN LENGTH AS LONG BINARY
    pb+=4
  end method



  method pop() as string
  '=====================
    if pb<4 then return ""
    '
    pb-=4         'POINT TO ITEM LENGTH ENCODING
    sys i=*buf+pb 'LENGTH OF ITEM
    sys ls=*i
    pb-=ls        'POINT TO START OF STRING
    '
    return mid buf,pb+1,ls
  end method
end class


StringStack s

s.push "Hello"
s.push "World"
print s.pop +"  "+s.pop

"


o2_asmo src
if len(o2_error) then
  print o2_error
  stop
end if


o2_exec

Charles

[largo_winch]

hello charles again, your new example still doesn't work as expected. my thinbasic_Oxygen.dll named from 9. octobre 2011. I've packed all in zip file. error appeared same as in my last post. after my idea the script stops because of an error here. no "hello world" messagebox was displayed. bye, largo