Can't ZAP File - In Use

[csda1]

Re: Can't ZAP File - In Use

Hi Robert,

I think I've got it figured out: Closing a form also closes an underlying table. (But you can't close the table that a form is based on, without closing the form itself.) ~ On this premise, there is no bug, but the [no table found] error returned is a bit misleading, and "subject to misinterpretation."[/INDENT]

(This is based upon testing in V8)

When you enumerate all open tables, you are getting a list of all tables (actually their aliases) from all sessions (threads) that have tables open. Almost all layouts (forms, browses, etc) are run in different sessions. When you do a table.get(tablenameAlias), it only gets a table from the current session. If you select a tablenameAlias that is not open in the current session (like the interactive window), it will not get the pointer to a non-open anything (and will error as well), hence you can't close that object either.

I'll add, that you probably can change the session effectively using a With/End With construct using a pointer to the other session's variable space, although I have not tried it with table.get(), so I can't say this as a fact. You can also do this in the Interactive Window by

Now suppose you got the pointer to another sessions table, using the menu "Set Interactive Window Session..." choice, table.get() should work with tables from that session, again untested as of this time.

However, leaving the session setting alone, here is what happens;

tbl=formname.Table_Get()
?tbl.name_get()
= "tablename"

Now that you have the form's table, try to close it. THIS WILL HANG ALPHA!!!

tbl.close()

When you switch to the form, it will display "Table not open" or similar message in a modal dialog box, that you will not be able to close, at which point you will need to close Alpha Five with the task manager.

Which basically comes down to the similar thing I preach about variables, do not delete/close resources that you did not create/invoke etc. While you can reference them all you want, and within reason, modify values of other threads, you must be careful when deleting it's required resources.

So you can close the form (which will delete the thread, table opens and other resources of it's thread), but you can't just go and delete it's underlying table.

So the next question is whether ?TABLE.enum_open() is checking to see if any of the tables attached to the database are open, or whether it is any table that is opened by Alpha, attached or not.

The answer is that it doesn't matter if it is attached, just whether it is open. Now Alpha has a function

a5_ForceCloseTables()

that will close all tables everywhere if they are not associated with a session (MDI window), but there is a fair amount of code done to enumerate all tables of other sessions and not delete those that are in other sessions. An orphan table will, however, be closed.

So there is really nothing special happening here, Alpha is acting in a reasonable way. It would have been nice for TABLE.enum_open() to return the associated window pointer object name (as an option), but they did not.

[SNusa]

Re: Can't ZAP File - In Use

It would have been nice for TABLE.enum_open() to return the associated window pointer object name (as an option), but they did not.

Thanks Ira;

Understood & thank you. ~I see how TABLE.enum_open() (if it returned a pointer) could have enabled one's code to (albeit dangerously) gain access to all the tables in other threads/sessions (forms,browses, scripts etc.) ~ "Feeling better now about this, as I'm seeing the light."

Hey, Ira, could you help me replace my Lenovo T61 BIOS with a working copy of Alpha5 v.11 Developer via remote desktop?
(Seriously though: I truly appreciate your responses here on this forum.)

PS everyone: I think that Ira just solved the OP's "ZAP" problem with the a5_ForceCloseTables() function!

[pboomwork]

Re: Can't ZAP File - In Use

I know this is a little late for this discussion but I have a generic function that addresses this issue.

I've working on a project that used several scripts that required exclusive access to tables, ZAP's imports stuff like that. However I wanted to run them from a button on a form that used the same table. I finally came up with the following generic function that allows this to happens. The original idea came from a xBasic code generated by the Genie for a backup operation. I think the code is well explained so I don't plan to say more other then;

Attach the following code to the OnPush event of your button on the form. Where ScriptToRun is your script that you want to run.

CloseAllWindowsRun("ScriptToRun")

'Date Created: 06-Feb-2013 11:57:47 AM
'Last Updated: 28-Jun-2013 08:59:23 AM
'Created By  : verboopa2
'Updated By  : verboopa2
FUNCTION CloseAllWindowsRun AS C (Script as C)
'---------------
'CloseAllWindowsRun
'---------------
	'This function closes all windows including the form or
	'browse it was launch from. The main menu is not closed.
	'It will then play the optional script specified as a 
	'parameter and finally reopen the form or browse it was lunched
	'from.

	'Normally it is not possible for a script launched from a 
	'form or browse to close that form or browse while it is
	'still running. The promper command can be executed but,
	'the window will not close till the script which is 
	'child of the form or browse is completed.
	'Sometimes a script needs exclusive access to a table that
	'is displayed by the underlying form. This is what this
	'script is for
	
	'The calling script must end after calling this function.
	'The script must be called from a form or browse.
	'This function can be used in the button OnPush Event to
	'launch the script in question.
	
	dim open_windows as c 		'List of open windows on system
	dim current_window as c 	'Current window that ran tis cript
	DIM varP_Window as p		'pointer to window about to be close
	
	dim topparent_name as c 	'used to close top parent
	dim cmd as c 
	dim condition as c 
	dim open_sessions as c 
	dim open_session_count as n 
	
	'Verify the top Parent is a form or browse
	if is_object(topparent.this) then 
		if topparent.class() <> "form" .and. topparent.class() <> "browse" then 
			ui_msg_box("Internal Error","CloseAllWindowRun was not called from a form or browse")
		end if
	else
		ui_msg_box("Internal Error","CloseAllWindowRun was not called from a form or browse")
	end if		

	'Tell the user what is about to happen give them a change to abort
	text = <<%text%
	You have selected an operation that requires exclusive access to all/some tables.
	
	If you are using eSum on multiple workstations this operation may fail if other users have the required tables open.
	
	If you proceeed all open windows will be closed. All edits in progress will be saved. No data will be lost!
	
	More information on the select operation will be given after this screen.
	
	The window you seolect the operation from will close if you proceed but it will be reopened at the end of the operation.
	%text%
	
	Dialog = <<%dlg%
	{region}
	{text=55,17:text};
	{endregion};
	{line=1,0};
	{region}
		 <*15&Proceed!Proceed>	 	<15&Cancel!CANCEL>
	{endregion};
	%dlg%
	
	Result = ui_dlg_box("eSum",Dialog)
	if Result <>"Proceed" then
	    end
	end if	

	
	'get list of open windows
	open_windows = a5_list_open_windows()	
	
	'remove current browse or form from this list
	'it is a special situation and will be treated differnently below
	if is_object(topparent.this)
		if topparent.class() = "form" .or. topparent.class() = "browse" then 
			current_window = topparent.name()
			'remove the current window from the list
			open_windows = word_subtract(open_windows,current_window,crlf())  
		end if 
	end if 
	
	'remove menu from list
	open_windows = word_subtract(open_windows,"menu",crlf())
	'remove control panel from list
	open_windows = word_subtract(open_windows,"ControlPanel",crlf())
	
	'now go through all windows and close them but see if they have any pending changes first
	for each Window in open_windows
	
		'If the window name was specified without a leading ":", then add it.
		if left(alltrim(Window),1) <> ":" then 
			Window = ":"+alltrim(Window)
		end if
		
		'Get a pointer to the specified window
		varP_Window = obj(Window)
	
		'The window does exist, so close it
		'Check to see that the object supports the "mode_get()" method
		if varP_Window.has_method("mode_get") then 
			'Save any unsaved data before closing the window
			DIM mode as c
			mode = varP_Window.mode_get()
			if (mode = "ENTER" .or. mode = "CHANGE")  then
				varP_Window.commit()
				'Check to see if the record was successfully saved
				if varP_Window.mode_get()<>"VIEW" then
					error_generate("Unable to save your changes Please correct and save, or discard your changes")
					end
				end if
			end if
		end if 
		'Close the window
		varP_window.close(.f.)
	
	next
	
	'Set up the commands to run when this script and it's calling script are done

	'Command to run before we reopen the window
	If .NOT. isnull(Script) then
	    cmd = cmd + crlf() + "script_play(" + quote(Script) + ")" + crlf()
	end if

	'sessions are used by expression that triggers these commands
	'when this script finally finishes the session count will drop
	open_sessions = session_enum()
	open_session_count = line_count(open_sessions)

	'The command needed to reopen the form or browse 
	if topparent.class() = "form" then 
		cmd = cmd + "dim tempP as p; tempP = form.view(" + quote(topparent.name(1)+"@" + topparent.Dictionary_Get(1))+")"
	else
		cmd = cmd + "dim tempP as p; tempP = browse.view(" +quote( topparent.name(1)+"@" + topparent.Dictionary_Get(1))+")"
	end if 
	
	if a5_IsMaximized() = .t. then 
		cmd =  cmd +  crlf() +"xbasic_wait_for_idle()" + crlf() +  "tempP.maximize()" + crlf()
	end if 
	
	'set up trigger that operates the commmands
	'when the number of sessions is one less than the number we currently
	'have then this script and the calling form or browse have closed
	condition = "line_count(session_enum()) =  " + (open_session_count - 1 )
	
	'is the control panel hidden? 
	'if so then you have to temporarily show it, or else the database will close
	'after you close this form.
	'Not needed where we leave Main Menu open but left
	'it in anyway doesn't hurt.
	if ControlPanel.IsVisible() = .f. then 
		ControlPanel.Minimize()
		cmd = cmd + crlf() + "controlpanel.hide()"
		if a5_IsMaximized() then 
			topparent.restore()
		end if 
	end if 

	'! Debug stuff
	'!trace.WriteLn("Commands to run when sessions")
	'!trace.WriteLn(cmd)
	'!trace.WriteLn("")
	
	'now set commands that will run once all this is done
	on_condition(condition,cmd)
	
	'finally the command that will close the calling window once these scripts are done
	topparent.close()

END FUNCTION