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How to clone an objectI have a simple object I load up from DB, Is there a easy way to clone it to
a new object of the same type ? Thanks On Mon, 9 Aug 2010 19:15:55 -0400, "Phil Hunt" <a**@aaa.com> wrote: Probably not. <g>>I have a simple object I load up from DB, Is there a easy way to clone it to >a new object of the same type ? > Depends on what you mean by "clone", ie, how much of a duplicate/copy do you need, or if you even need one? Cloning 'data' always takes you into the realm of "Shallow Copies" or "Deep Copies", but in some cases it isn't the data but the objects's behavior or state we want to 'clone'. (The ADO Recordset.Clone is an example of the latter.) We need more information. -ralph I am more interested in the data. As I am changing data, I want to 'undo'
the change just by reverting back to the clone. Show quoteHide quote "ralph" <nt_consultin***@yahoo.net> wrote in message news:haa166hspc24r3esjk8h0u712u2jebjcng@4ax.com... > On Mon, 9 Aug 2010 19:15:55 -0400, "Phil Hunt" <a**@aaa.com> wrote: > >>I have a simple object I load up from DB, Is there a easy way to clone it >>to >>a new object of the same type ? >> > > Probably not. <g> > > Depends on what you mean by "clone", ie, how much of a duplicate/copy > do you need, or if you even need one? > > Cloning 'data' always takes you into the realm of "Shallow Copies" or > "Deep Copies", but in some cases it isn't the data but the objects's > behavior or state we want to 'clone'. (The ADO Recordset.Clone is an > example of the latter.) > > We need more information. > > -ralph On Mon, 9 Aug 2010 21:41:28 -0400, "phil hunt" <a@abc.com> wrote: Don't know what your 'data' looks like, but assuming it is a group of>I am more interested in the data. As I am changing data, I want to 'undo' >the change just by reverting back to the clone. > > properties, this is often accomplished by storing the last value for each of your properties/attributes as a backup. Which is something I figure you have already considered. Takes a bit of work. It means everytime you change something, you have to reassign the 'backup'. If for some reason you want to undo, you either have to create new 'Undo' method for each value, or do a blanket 'put-back'. So it depends on how and when you feel you might need to undo, and the granularity - per item, per process, per run, etc. Perhaps 'Serialization' would be something to look into. For objects that actually refers to packaging up all the data/state, etc and trasporting it, or storing it, so you can come back later and read the info to recreate the object. But you can also simply considered the serialized data as a backup. Your object would have a 'Save' method, just before you planned to do something dangerous, where it simply stores everything. Then an 'Undo' on an Oops. <g> This also has the advantage of being able to perform muliple undos. For an example, I have often done this for disconnected ADODB.Recordsets, by wrapping the Recordset with my own object. Then use the contained Recordset.Save feature to store a copy to a file. Bang around on the original Recordset, then if I have to go back, reload a new from the file. But again it depends on what is needed for YOUR problem domain. Any option you chose will look like a lot of typing, thus not easy, but once you pick a particular strategy, most of it will be boiler-plate. -ralph On Mon, 09 Aug 2010 21:28:53 -0500, ralph <nt_consultin***@yahoo.net>
wrote: >On Mon, 9 Aug 2010 21:41:28 -0400, "phil hunt" <a@abc.com> wrote: Another strategy that is occasionally useful, is based on a timeless> >>I am more interested in the data. As I am changing data, I want to 'undo' >>the change just by reverting back to the clone. >> >> > principle of programming: "There is no problem that can't be resolve with another layer of indirection". <g> Wrap your object with one that combines a factory with storage. -ralph It sounds too much like work. Maybe some other time. But I am curious what
you mean by 'factory'. I came across them in some other language, but not VB6 Show quoteHide quote "ralph" <nt_consultin***@yahoo.net> wrote in message news:4fe166538h1e7enblsfdm460dgfjaa1bs6@4ax.com... > On Mon, 09 Aug 2010 21:28:53 -0500, ralph <nt_consultin***@yahoo.net> > wrote: > >>On Mon, 9 Aug 2010 21:41:28 -0400, "phil hunt" <a@abc.com> wrote: >> >>>I am more interested in the data. As I am changing data, I want to 'undo' >>>the change just by reverting back to the clone. >>> >>> >> > > Another strategy that is occasionally useful, is based on a timeless > principle of programming: "There is no problem that can't be resolve > with another layer of indirection". <g> > > Wrap your object with one that combines a factory with storage. > > -ralph On Mon, 9 Aug 2010 23:45:37 -0400, "phil hunt" <a@abc.com> wrote: A Factory pattern/method is where you define an interface for creating>It sounds too much like work. Maybe some other time. But I am curious what >you mean by 'factory'. I came across them in some other language, but not >VB6 > an object, and then let it decide who and what to create. In your case also providing a Proxy - a surrogate to control access to the object/s created. eg, swapping out objects with the client being none the wiser. Factory (and Proxy) are what is called 'Design Patterns'. A way of describing general reuseable software architecture. http://en.wikipedia.org/wiki/Design_pattern_(computer_science) and http://en.wikipedia.org/wiki/Factory_method_pattern A Factory/Proxy in this case, would be a mechanism to simply store whole objects instead of serializing them. -ralph phil hunt wrote:
> I am more interested in the data. As I am changing data, I want to 'undo' If you want to ignore all changes to your object, then the easiest thing > the change just by reverting back to the clone. to do is simply throw it away and reload it from the database. Cloning would probably mean you have to write code to serialise and deserialise your object's state (unless you use Ralph's suggestion of saving the ADO recordset you used to populate your object, to XML). If, however, you needed to keep track of changes to each property - so you can undo undo changes one property at a time - then you probably want to keep a LIFO stack containing your changes. Many use code generation (eg one class per table) to solve this sort of problem, especially if similar code is required for many classes. "Phil Hunt" <a**@aaa.com> wrote in message MZTools lists all properties of your classes when you use "Generate XML news:%2333oQjBOLHA.4824@TK2MSFTNGP05.phx.gbl... >I have a simple object I load up from DB, Is there a easy way to clone it >to a new object of the same type ? Documentation". You need to copy them to Excel or similar program to extract property names. Also, the code below dumps a list of properties, methods, and events of your class from Object Browser, so you can easily write code to save the contents. It uses SendKeys and copy from the Clipboard. To use it, bring up Object Browser(F2), then select your project name from the list, then click on your class. You would see the list of properties on the right pan. Right click anywhere and make sure that "Group Members" is selected. Click on the first property on the right pan, then start a new VB IDE instance, add a Timer to Form1, then add the code below. Run the project, and switch to the VB IDE that is showing Object Browser. After 5 seconds, the running program would capture property names and print them to the immediate window. From there, you can copy them and do with them whatever you want. Option Explicit Private Sub Form_Load() Timer1.Interval = 5000 End Sub Private Sub Timer1_Timer() Timer1.Enabled = False DumpObjectBrowser End Sub Private Sub DumpObjectBrowser() Dim Str As String Dim LastStr As String Dim Counter As Long Clipboard.Clear Counter = 0 Do LastStr = Str SendKeys "^c", True Delay 0.1 Str = Clipboard.GetText If LastStr = Str Then ' We reached the end Exit Do End If Debug.Print Str SendKeys "{DOWN}", True Delay 0.1 Counter = Counter + 1 Loop Until Counter = 100 Me.Caption = "Done!" End Sub Private Sub Delay(ByVal Seconds As Single) Dim t As Single t = Timer Do While Abs(Timer - t) < Seconds DoEvents Loop End Sub Intersting.
I am thinking about cloning the data, not the definition. It is academic now. But can I use a Property bag in my situation. I seen it, but never play with it. Show quoteHide quote "Nobody" <nob***@nobody.com> wrote in message news:i3rmlh$c7r$1@speranza.aioe.org... > "Phil Hunt" <a**@aaa.com> wrote in message > news:%2333oQjBOLHA.4824@TK2MSFTNGP05.phx.gbl... >>I have a simple object I load up from DB, Is there a easy way to clone it >>to a new object of the same type ? > > MZTools lists all properties of your classes when you use "Generate XML > Documentation". You need to copy them to Excel or similar program to > extract property names. > > Also, the code below dumps a list of properties, methods, and events of > your class from Object Browser, so you can easily write code to save the > contents. It uses SendKeys and copy from the Clipboard. To use it, bring > up Object Browser(F2), then select your project name from the list, then > click on your class. You would see the list of properties on the right > pan. Right click anywhere and make sure that "Group Members" is selected. > Click on the first property on the right pan, then start a new VB IDE > instance, add a Timer to Form1, then add the code below. Run the project, > and switch to the VB IDE that is showing Object Browser. After 5 seconds, > the running program would capture property names and print them to the > immediate window. From there, you can copy them and do with them whatever > you want. > > Option Explicit > > Private Sub Form_Load() > Timer1.Interval = 5000 > End Sub > > Private Sub Timer1_Timer() > Timer1.Enabled = False > DumpObjectBrowser > End Sub > > Private Sub DumpObjectBrowser() > Dim Str As String > Dim LastStr As String > Dim Counter As Long > > Clipboard.Clear > Counter = 0 > Do > LastStr = Str > SendKeys "^c", True > Delay 0.1 > Str = Clipboard.GetText > If LastStr = Str Then > ' We reached the end > Exit Do > End If > Debug.Print Str > SendKeys "{DOWN}", True > Delay 0.1 > Counter = Counter + 1 > Loop Until Counter = 100 > Me.Caption = "Done!" > End Sub > > Private Sub Delay(ByVal Seconds As Single) > Dim t As Single > > t = Timer > Do While Abs(Timer - t) < Seconds > DoEvents > Loop > End Sub > > > On Tue, 10 Aug 2010 11:05:40 -0400, "Phil Hunt" <a**@aaa.com> wrote: lol>Intersting. >I am thinking about cloning the data, not the definition. >It is academic now. But can I use a Property bag in my situation. I seen it, >but never play with it. > VB's built-in serialization product. Glad you stumbled across it. I'd forgotten about them, and you did ask for "easy" too. Dop! <g> Just a word of warning. Property Bags store data as Variants and as we know VB is very obliging when it comes to coercing a value into a Variant, or in coercing a value out of one. Dates and alphanumeric strings can often be troublesome. So make sure you have clear business rules for conversion. It also is useful to add additional "format" or "type" properties to insure there are no misunderstandings. -ralph On 10/08/2010 17:17, ralph wrote:
Show quoteHide quote > On Tue, 10 Aug 2010 11:05:40 -0400, "Phil Hunt"<***@aaa.com> wrote: The data in a property bag is typed, it may be implicit via the variant > >> Intersting. >> I am thinking about cloning the data, not the definition. >> It is academic now. But can I use a Property bag in my situation. I seen it, >> but never play with it. >> > > lol > > VB's built-in serialization product. > > Glad you stumbled across it. I'd forgotten about them, and you did ask > for "easy" too. Dop!<g> > > Just a word of warning. Property Bags store data as Variants and as we > know VB is very obliging when it comes to coercing a value into a > Variant, or in coercing a value out of one. Dates and alphanumeric > strings can often be troublesome. So make sure you have clear business > rules for conversion. It also is useful to add additional "format" or > "type" properties to insure there are no misunderstandings. type, but you do get out the same data type you put in. -- Dee Earley (dee.ear***@icode.co.uk) i-Catcher Development Team iCode Systems (Replies direct to my email address will be ignored. Please reply to the group.) On Tue, 10 Aug 2010 17:29:20 +0100, Dee Earley
<dee.ear***@icode.co.uk> wrote: > An absolute given. >The data in a property bag is typed, it may be implicit via the variant >type, but you do get out the same data type you put in. I stand corrected, and the OP should ignore my advice as absolutely nothing can ever go wrong. -ralph On that note, please considered it closed.
Show quoteHide quote "ralph" <nt_consultin***@yahoo.net> wrote in message news:al0366llu6epngs7udnlhqoett4c70rsns@4ax.com... > On Tue, 10 Aug 2010 17:29:20 +0100, Dee Earley > <dee.ear***@icode.co.uk> wrote: > > >> >>The data in a property bag is typed, it may be implicit via the variant >>type, but you do get out the same data type you put in. > > An absolute given. > > I stand corrected, and the OP should ignore my advice as absolutely > nothing can ever go wrong. > > -ralph 
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