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Hi,
I got a COM, I tried to used it in C#, but curiously I can't access some of the properties (nor seeing them all in the Object Browser - but it does work in JScript). Anyone could help ?
Here is what I can see from OleViewer (from which only the "Count" property I can access).
interface IFWRuleList : IDispatch {
[id(0xfffffffc), propget]
HRESULT _NewEnum([out, retval] IUnknown** enumerator);
[id(00000000), propget]
HRESULT Item(
[in] long index,
[out, retval] VARIANT* value);
[id(0x00000001), propget]
HRESULT Count([out, retval] long* Count);
hny
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Hello All,
I was trying to create dynamic HTML table using C#. The data for the table comes from sql server filled datatable (i have succeded in this aspect), I am not able to figure out how to create HTML table with this data. Any suggestions are welcome.
Thanks in Advance for your help. Best Regards
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you have htmltable, htmltablerow, htmltablecell
first, set the cell data using htmaltablecell's innerhtml property
next, add this cell to the row,
finally add the row to the table using its property rows.add(tablerow)
Gautham
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Thanks i have done this and it works fine could you please tell me how to display the data in three columns instead of one column.
<asp:gridview id="GridView1" runat="server" autogeneratecolumns="False" height="1048px">
<columns>
<asp:templatefield>
<itemtemplate>
| " width="120" height="100" border="0"> | | | | $<%# Eval("Price") %> | | | <%# Eval("ProductName") %> | | |
cheers, shilpa.
Thanks in Advance for your help. Best Regards
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Could anyone tell me if OOP is used much in scientific applications please?
I've gotten the impression from some sources that OOP is mainly used in
large office and financial app's...
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Lurker00 wrote: mainly used in
large office and financial app's...
Probably true, in that there are probably more of them written.
Given the speed of PCs today, I see no need for you to use plain C for scientific code, which means there's no reason not to use OOP. Certainly, if you're using C#, you will use OOP, you have no choice.
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
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I agree with your points. I don't see why one couldn't use OOP in scientific programming.
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I think it's a matter of whether or not OOP makes sense. For example, a scientific application dealing with specific representations of numbers (in a matrix, perhaps) and operating on those representations would do well to use OOP. I'd say that C is probably best in a compact (few KB in size), high-performance scientific library.
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the answer i've always heard on this is that OO code is seen as non-deterministic by a lot of scientists. The scientific code i have seen written in OO languages tends to separate the entity objects from the control objects which largely gets round these problems
The few scientific computer users i know are all Fortran users and i suspect that they are using libraries that have been developed and performance tuned over the course of many years, unlike banks, scientific institutions often have small budgets and loads of inertia.
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Hello everybody, I have been trying to make my own control. I have looked at some articles such as the combo-box based color picker[^], but I still don't get how I am supposed to make my own control. If anyone has had any success with a certain article, I would greatly appreciate a link to it.
Thanks.
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You start by adding a new control to your project, it's an object type. You then get an area like the forms designer, but the controls you add to it, are added to your control. You obviously get to add code to it as well, just like a form. The process is really the same, all that differs is the base class, really.
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
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I'm creating C# MONO/.NET 2 Winforms application.
I need to enter part names but store part ids in orders table.
I set Combobox Datasource to parts table.
Since parts table is very big, it takes a lot of time to load the data source.
How to use lookup table when lookup table is large ?
Is it possible to use virtual combobox or some other control?
Andrus
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Use a hashtable. How big are we talking ?
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
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Thank you.
I asked for a WinForms control like which shows first 10 parts whose name starts with entered name.
User can scroll and see next or previous 10 part names. In this case combobox should ask next 10 rows from server etc.
Total table size is from 100 .. 500000 record depending on the user and it is not reasonable to load it as combobox lookup table
during combobox creation like ms doc sample recommends.
Hashtable is not UI control and cannot used for this.
This should be common requirement. Where to find code which implements this ?
Andrus
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Ah, OK. I thought you wanted to look up values and then display them.
AndrusM wrote: This should be common requirement.
I don't think it is.
I know that comboboxes offer auto complete, perhaps you can find something there ? I'm not sure if it works with a callback, or just a data source.
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
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for auto-complete combobox need to read whole lookup table in init which is not reasonable for large tables.
I'm looking for a virtual combobox control which reads data from sql server only when user actually needs it.
Andrus
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To me it sounds like you should have a BackgroundWorker that will load the data in small pieces and then add them (when possible, or by request) to the combo box.
I am wondering weather you really need a combo box though.. Wouldn't a ListView be better?
Internet - the worlds biggest dictionary
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Backgroundworker is too complicated for this task.
Usually user type first characters of name and want to see 10 matching character. It is best that control reads data only from server when user requestes autocomplete or opens dropdown menu.
ListView takes a lot of screen space.
I need singe-line width field, autocomplete and selection from dropdown table.
I think that combobox nearest to those requirements
Andrus
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Hello,
I've recently posted a question about destructors.
The replies here made me go on a journy of articles reading.
Of course I got wiser , but there's something I'm still not sure about...
If I have a class which holds non-disposable objects, how should I go about releasing my object?
Should I not implement IDisposable?
Should I only set their references to null?
Should I write a finalizer method?
Also, is a finalizer needed if I don't have a Dispode() method?
Thanks in advance,
Shy.
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You need a Dispose method if you want to offer a way to free memory immediately, or if you hold on to things like window handles or database connections, which need to be released. Yes, you should also write a finaliser, this is eventually called by the system, it should check if dispose was called, and if not, clean up for your class.
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
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What should I do in the following scenario...?
Class X is holding reference to disposable objects, but should not dispose of them, as the referenced objects are used somewhere else (outside of the class).
Lets say that the instance of X is no more in use, and should now be disposed of.
Should I use a finalizer method in order to set X's inner references to null?
Or maybe it is done automatically, and a finalizer method will only be a nag on performance?
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You probably want to wrap the object that needs disposing in another class, which impliments a reference count. This means, you keep track of how many objects are using your object, and when the counter drops to 0, you call Dispose.
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
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It's possible that I didn't understand exactly what you meant, But what should I do with the inner references?
I'm not really sure as for the following, but AFAIK the GC will not collect an object which is still referenced somewhere.
Lets say both class A and B are referencing an object (and they both should NOT dispose of it). A and B are the only ones holding a reference to the object.
B should now be disposed of, but does not set the reference to the object to null.
Now A is disposing and sets the reference to the object to null.
Would the GC identify it needs to collect the object?
Or maybe it would decide not to collect it, because it is, seemingly of course, still referenced by the disposed/finalized B?
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shyagam wrote: AFAIK the GC will not collect an object which is still referenced somewhere.
Correct. But, the issue is, you want to manage cleanup of some resources, right?
My point would be something like this
object C is the object that both A and B refer to.
object C contains a resource, which needs disposing of
object C keeps track of how many objects are referring to it
object A and B both refer to object C. So it has a reference count of 2.
object A calls Dispose and sets it's reference to null. object C internally does not dispose of the resource it holds, but it does drop it's counter to 1.
object B calls Dispose and sets it's reference to null. object C notices that it's reference count is now 0, so it calls Dispose on the resource in question
The GC cleans up the rest of object C, as nothing has references to it.
Christian Graus - Microsoft MVP - C++
Metal Musings - Rex and my new metal blog
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shyagam wrote: AFAIK the GC will not collect an object which is still referenced somewhere
This is not correct. The "somewhere" in your statement must still be alive:
if the only references to Y are from inside objects that themselves are no longer
referenced, object Y is collectable (Otherwise two objects with cyclic references
would never die).
Furthermore, I would discourage the use of reference counts; it is cumbersome,
and when it goes wrong, your code becomes unsafe. It is better to create
a class Z (possibly a singleton) that holds your special resources, and has a Dispose
if applicable; when an object of class Z happens to be no longer referenced,
it becomes collectable (and its finalizer would call its Dispose in case you have
forgotten to call Dispose explicitly).
Remember: you should always call Dispose for objects that offer such method.
(On some classes it may have a different name, e.g. File.Close).
Luc Pattyn
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