Saving decision tree
in [Visual Basic]
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From: Alexandros Peropulous on 23 Jul 2010 14:06 My decision tree is organised as a class right now. Is there a way to save a class to a file? Sounds impossible to me. I tried it with a Put and Get statement, but that gave me a Type Mismatch error. Greetings Alex
From: ralph on 23 Jul 2010 14:55 On Fri, 23 Jul 2010 20:06:42 +0200, Alexandros Peropulous <peropero(a)gmail.com> wrote: >My decision tree is organised as a class right now. >Is there a way to save a class to a file? Sounds impossible to me. >I tried it with a Put and Get statement, but that gave me a Type >Mismatch error. > Converting an object (or data structure) into a series of values for storage, and the process for 're-converting' the storage back into an object is called Serialization. http://en.wikipedia.org/wiki/Serialization VB provides no native support for serialization. So you need to write your own, which isn't that difficult. It is pretty much boilerplate - which is why so many OPLs do natively support serialization. A class is merely instructions for creating an object. It defines the attributes (data) and behavior (methods). At it simplest level just define a data structure to package the attributes and provide method/s to create or receive it. [Warning! Simple psuedocode follows ...] For example, A simple class that packages its data into a comma-delimited string. ' class A Long lJunk String sJunk FromString( csvString ) ToString() As String ' end class In code ... ' fetch Open file s = Get String Set obj = New CSomeObject obj.FromString s ' you now have a new CSomeObject ' save Open file Save obj.ToString .... -ralph
From: Larry Serflaten on 23 Jul 2010 15:00 "Alexandros Peropulous" <peropero(a)gmail.com> wrote > My decision tree is organised as a class right now. > Is there a way to save a class to a file? Sounds impossible to me. > I tried it with a Put and Get statement, but that gave me a Type > Mismatch error. You have to convert your class' data to serial form (a string, or an array) and save that to disk. When you read that back in, you have to convert the serial form back into class data. There are different ways to do that, but the conversion is left up to you to do. VB does not provide a generic way to convert your objects for you. LFS
From: Larry Serflaten on 23 Jul 2010 18:34 "ralph" <nt_consulting64(a)yahoo.net> wrote > [Warning! Simple psuedocode follows ...] > For example, > A simple class that packages its data into a comma-delimited > string. > ' class A > Long lJunk > String sJunk > FromString( csvString ) > ToString() As String > ' end class Some objects provide a Clone function that returns a duplicate copy of the object. For serialization I often recommend using a Copy property: Public Property Get Copy() As String ' code to serialize class data End Property Public Property Let Copy(Data As String) ' code to de-serialize class data End Property I just think that provides for better syntax. Compare the different syntax needed to create a clone: ' Clone Set bb = aa.Clone() ' To/From string Set bb = New class bb.FromString(aa.ToString) ' Copy Set bb = New class bb.Copy = aa.Copy Just another 2� LFS
From: ralph on 23 Jul 2010 19:38
On Fri, 23 Jul 2010 17:34:10 -0500, "Larry Serflaten" <serflaten(a)gmail.com> wrote: > >Some objects provide a Clone function that returns a duplicate >copy of the object. For serialization I often recommend using a >Copy property: > > > Public Property Get Copy() As String > ' code to serialize class data > End Property > > Public Property Let Copy(Data As String) > ' code to de-serialize class data > End Property > > >I just think that provides for better syntax. Compare the >different syntax needed to create a clone: > >' Clone >Set bb = aa.Clone() > >' To/From string >Set bb = New class >bb.FromString(aa.ToString) > >' Copy >Set bb = New class >bb.Copy = aa.Copy > > >Just another 2� >LFS > Copying or Clone making, and Serialization are related as they are processes for managing an object's attributes for either immediate or delayed creation of a 'new' object, but IMHO are subtly different and semantically best managed separately. Cloning for example, can lead to Prototype or Factory designs. [Although I have no disagreement with your scheme. What ever works.] Based on what little I know of the OP's needs I would probably adopt a scheme similar to the ADODB.Recordset and encapsulate the entire i/o within the object. MyObject.Save "full_filename_path", ccPersistCVS | ccPersistXML .... or any other location or format that might be useful Then to retrieve Set MyObject = New CMyObject MyObject.Open "full_filename_path" I suspect that you put 5 programmers in a room you would come up with 6 possible solutions. <g> -ralph |