[RESOLVED] How to prevent deleting dynamic objects

In an SDI app, typically the CFormView reads its display data from the document. As such, any modification to this data must be persisted back to the document. Okay, now onto the dialog. What need to do is load the dialog's data on creation and save it back in OnOk(). To make this easier, just pass a pointer to the document when you create the dialog.

// Invoked by some view handler
CMyDialog dlg( AfxGetDocument( ) );
dlg.DoModal( );

From there you just need to connect up the data from the document to the controls.

You can do this the traditional way of using the 'Add variable' method and DDX.

If you don't know how to do this, post back.

P.S. There is another cleaner way to do this, but you have to understand the 'Add Variable' method first.

No. I was referring to staticly created controls (i.e. created in a dialog or formview template).

Do you need to create your controls dynamically? I mean, do you have a variable # or type of controls at runtime? If so, it is much more difficult to wire them up to the data because you can't just use the default DDX mechanism to let MFC handle the data chores (I guess you can make dynamic DDX entries yourself but this is pretty advanced stuff).

Can you post back if dynamic controls are a necessity?

Since you are using dynamic controls, I don't believe you can use the default DDX mechanism to wire up the data (although I assume it would be possible to create the DDX map entries - still there might not be much gain for the effort).

I would probably continue to track the controls in the vector as you are doing, but be sure to walk the memory and destroy and delete each control before closing the dialog. Everything that is associated with the display portion of the dialog should be cleaned up when the dialog goes out of scope (if you are using modal dialogs anyway).

You are still going to have to track the data associated with each dynamic control in the document.

Can you give me an example of the type of data you are storing (if you don't want to specify the exact data, make something up :gap:).

I am assuming that each 'number' the user selects contains a 'set' of data.

I think I might be able to offer an alternative based on the types of data.

At this time i just wan't to concentrate on reopen my dialog with the same number of controlls, placement, size and id's as before closing. And i don't know hot to do this. After app start i have main view with button, when clicked on it dialog appears and now user puts some controls and decide its placement. Next user close dialog (not main window), and reopens again and want to see everything what he done before (if he created 10 buttons he want them to be there at next opening). If i delete all dynamic data before closing dialog as you said, how i can reload all controlls structure, position, size etc...??

At this time i just wan't to concentrate on reopen my dialog with the same number of controlls, placement, size and id's as before closing. And i don't know hot to do this. After app start i have main view with button, when clicked on it dialog appears and now user puts some controls and decide its placement. Next user close dialog (not main window), and reopens again and want to see everything what he done before (if he created 10 buttons he want them to be there at next opening). If i delete all dynamic data before closing dialog as you said, how i can reload all controlls structure, position, size etc...??I believe I finally understand what this application does. It sounds like this app allows a user to build a UI by adding controls to a dialog. Different users are allowed to add a different number and type of controls. If this is not correct, then please describe the application in more detail.

Assuming the app's functionality is how I described it, what you need to track in a 'data' sense is the metadata for the controls associated with a user. For each user, you will need to track the type of control, the position of the control on the layout and the type of data that the controls store. I would envision that each user object has a list with 'control' entries in it - with each entry storing the position and type for each control. The document simply stores a list for each user.

When the 'layout' dialog opens, it just reads the data from the document for that user and starts building the controls one at a time. When the dialog is saved, it just saves the user data back to the document.

In terms of dialog control creation/destruction, when the 'layout' dialog is created with DoModal, the controls on the page are dynamically created and then destroyed when the dialog closes. So while the controls are always created/destroyed each time the dialog opens, the meta-data to describe the controls for the user is always persisted in the document.

This app allows user to create very simple block diagram of some controller, lets say user just decide how many parts this block diagram will have. Those blocks are only buttons positionet to look like some kind of diagram. User opens this dialog to design this diagram at the beggining or to make some changes later (all at app run, app is not restarted and no saving anything to file). When he design this diagram he close it and open other dialog to test what he design. If something go wrong he reopenst dialog with his diagram and correct what he wants (user is always 1, no multiuser need). ??Okay, the design is similar to what I described.

I don't know if i understand what you mean. You wan't me to get size, position, id and type for each controll and store it in vector in document?If you only ever use buttons, then you don't need to store the type, but otherwise yes. The document will contain the list of users. Each user will contain the metadata list of controls (you don't need to use a vector because you don't need a container with contiguous memory - a list is more appropriate here).

There is another thing that bother me, if i create some e.g. "integer" variable dynamically in this dialog and point to this variable by some pointer that is member of this dialog class, i can close and reopen this dialog and stilla have acces to this value. If i set this integer to 20, then close dialog and reopen it i still can read that value is 20. Why with Buttons and its pointers i can't do that??Because you are creating the child controls of the dialog dynamically and destroying these controls when you close the dialog. If you were to store the pointers to the controls, they would be meaningless to the dialog when you re-opened it (because the control that used to belong to the pointer was destroyed the last time the dialog was closed - so now the pointer is invalid).

All you need to do is pass in the pointer to the User class into the dialog when you call domodal. In the OnInitDialog method, you will loop through the 'controls' list and create the controls. For each entry in the 'controls' list, you will call pBtn->Create and pass in the appropriate size and name info.

Great. Okay one minor suggestion. Now that you have it working with 3 vectors, replace that code with one vector that holds a class or structure (the class or structure would hold size/placement, ID, style, and description.

There isn't any reason to use 3 vectors when you can use 1 vector that contains a class (or structure) with all the necessary info for the control.

...and you were thinking I was going to suggest replacing the vector with a list. :D