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  • C#: Populating a UI using separate threads.

    - by Andrew
    I'm trying to make some sense out of an application Ive been handed in order to track down the source of an error. Theres a bit of code (simplified here) which creates four threads which in turn populate list views on the main form. Each method gets data from the database and retrieves graphics from a resource dll in order to directly populate an imagelist and listview. From what Ive read on here (link) updating UI elements from any thread other than the UI thread should not be done, and yet this appears to work? Thread t0 = new Thread(new ThreadStart(PopulateListView1)); t0.IsBackground = true; t0.Start(); Thread t1 = new Thread(new ThreadStart(PopulateListView2)); t1.Start(); Thread t2 = new Thread(new ThreadStart(PopulateListView3)); t2.Start(); Thread t3 = new Thread(new ThreadStart(PopulateListView4)); t3.Start(); The error itself is a System.InvalidOperationException "Image cannot be added to the ImageList." which has me wondering if the above code is linked in some way. Iis this method of populating the UI recommended and if not what are the possible complications resulting from it?

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  • RTTI and Portability in C++

    - by Joshua
    If a compiler doesn't "support" RTTI, does that mean that the compiler can not handle class hierarchies that have virtual functions in them? Or have I been misunderstanding the literature about how RTTI isn't portable, and the issues lie elsewhere?

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  • How to execute a program from file descriptor?

    - by stribika
    I need to execute a file when I only know the descriptor. It is also possible that there are no links to the file so finding out the name somehow is not an option. All the execve(), execvp(), etc functions take a file name. dlopen() also takes a name. Ugly solutions (like reading the file and calling some function pointer) are OK.

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  • idiomatic way to take groups of n items from a list in Python?

    - by Wang
    Given a list A = [1 2 3 4 5 6] Is there any idiomatic (Pythonic) way to iterate over it as though it were B = [(1, 2) (3, 4) (5, 6)] other than indexing? That feels like a holdover from C: for a1,a2 in [ (A[i], A[i+1]) for i in range(0, len(A), 2) ]: I can't help but feel there should be some clever hack using itertools or slicing or something. (Of course, two at a time is just an example; I'd like a solution that works for any n.) Edit: related http://stackoverflow.com/questions/1162592/iterate-over-a-string-2-or-n-characters-at-a-time-in-python but even the cleanest solution (accepted, using zip) doesn't generalize well to higher n without a list comprehension and *-notation.

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  • Cannot use a Like query in a JSP prepared statement?

    - by SeerUK
    OK, first the query code and query: ps = conn.prepareStatement("select instance_id, ? from eam_measurement where resource_id in (select RESOURCE_ID from eam_res_grp_res_map where resource_group_id = ?) and DSN like '?' order by 2"); ps.setString(1,"SUBSTR(DSN,27,16)"); ps.setInt(2,defaultWasGroup); ps.setString(3,"%Module=jvmRuntimeModule:freeMemory%"); rs = ps.executeQuery(); while (rs.next()) { bla blah blah blah ... Returns an empty resultSet. Through basic debugging I have found its the 3rd bind that is the problem i.e. DSN like '?' I have tried all kinds of variations, the most sensible of which seemed to be using: DSN like concat('%',?,'%') bit that doesn' work as I am missing the ' ' either side of the concatenated string so I try DSN like ' concat('%',Module=P_STAG_JDBC01:poolSize,'%') ' order by 2 but I just can't seem to find a way to get them in that works. What am I missing? :) Thanks!

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  • mySQL query: How to insert with UNION?

    - by Industrial
    Hi everybody, I am kind of new to mySQL:s union functions, at least when doing inserts with them. I have gotten the following to work based upon a example found on the net: INSERT INTO tableOne(a, b) SELECT a, $var FROM tableOne WHERE b = $var2 UNION ALL SELECT $var,$var Ok, nothing strange about that. But what happens when I want to insert a third value into the database that has nothing to do with the logic of the Select being done? Like : INSERT INTO tableOne(a, b, c ) How could that be done?

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  • Determining if Memory Pointer is Valid - C++

    - by Jim Fell
    It has been my observation that if free( ptr ) is called where ptr is not a valid pointer to system-allocated memory, an access violation occurs. Let's say that I call free like this: LPVOID ptr = (LPVOID)0x12345678; free( ptr ); This will most definitely cause an access violation. Is there a way to test that the memory location pointed to by ptr is valid system-allocated memory? It seems to me that the the memory management part of the Windows OS kernel must know what memory has been allocated and what memory remains for allocation. Otherwise, how could it know if enough memory remains to satisfy a given request? (rhetorical) That said, it seems reasonable to conclude that there must be a function (or set of functions) that would allow a user to determine if a pointer is valid system-allocated memory. Perhaps Microsoft has not made these functions public. If Microsoft has not provided such an API, I can only presume that it was for an intentional and specific reason. Would providing such a hook into the system prose a significant threat to system security? Situation Report Although knowing whether a memory pointer is valid could be useful in many scenarios, this is my particular situation: I am writing a driver for a new piece of hardware that is to replace an existing piece of hardware that connects to the PC via USB. My mandate is to write the new driver such that calls to the existing API for the current driver will continue to work in the PC applications in which it is used. Thus the only required changes to existing applications is to load the appropriate driver DLL(s) at startup. The problem here is that the existing driver uses a callback to send received serial messages to the application; a pointer to allocated memory containing the message is passed from the driver to the application via the callback. It is then the responsibility of the application to call another driver API to free the memory by passing back the same pointer from the application to the driver. In this scenario the second API has no way to determine if the application has actually passed back a pointer to valid memory.

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  • deep or shallow copying?

    - by Dervin Thunk
    Dear all. I was wondering if there are examples of situations where you would purposefully pass an argument by value (deep copy) in C. For instance, passing a char to a function is usually cheaper in space than passing a char* (if there's no need to share the value), since char is 1 byte and pointers are, well, whatever they are in the architecture (4 in my 32 bit machine). ?(When) do you want to pass (big) deep copies to functions? if so, why?

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  • Classes. Whats the point?

    - by Ben Shelock
    I'm fairly new to OOP in PHP, I've made a couple of basic scripts but nothing impressive. All I've really taken from it is that it would probably be easier just make a collection of functions and include them. The structure of classes seems to just confuse what was otherwise a simple process. And in collating everything into a class it doesn't really add any functionality. So I'm clearly missing something. Could someone explain what functionality is added by creating classes

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  • 64-bit integers in Cython

    - by Homayoon
    I'm trying to interface a C++ library (pHash) with Python using Cython, but I have trouble with some of the types. The library functions use "unsigned long long" and I can't find a way to declare variables and parameters with this type. I searched for a list of the types that I can use with cdef but I found nothing. Can anyone point me to such a list (if it exists) or otherwise suggest a way to use 64 bit types in Cython? Thanks.

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  • Opinions on platform game actor/background collision resolving

    - by Kawa
    Imagine the following scenario: I have a level whose physical structure is built up from a collection of bounding rectangles, combined with prerendered bitmap backgrounds. My actors, including the player character, all have their own bounding rectangle. If an actor manages to get stuck inside a level block, partially or otherwise, it'll need to be shifted out again, so that it is flush against the block. The untested technique I thought up during bio break is as follows: If an actor's box is found to intersect a level box, determine where the centerpoints of each rect are. If the actor's center is higher than the level box's, move the actor so that the bottom of the actor's rect is flush with the top of the level's rect, and vice versa if it's lower. Then do a similar thing horizontally. Opinions on that? Suggestions on better methods? Actually, the bounding rects are XNA BoundingBlocks with their Z spanning from -1 to 1, but it's still 2D gameplay.

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  • Populate table fields on query execution

    - by Jason
    I'm trying to build an ASP site that populates a Table based on the results of a selection in a ListBox. In order to do this, I've created a GridView table inside a div element. Currently the default behavior is to show all the items in the specified table in sortable order. However, I'd like to refine this further to allow for display of matches based on the results from the ListBox selection, but am not sure how to execute this. The ListBox fires off a OnSelectionChanged event to the method defined below and the GridView element is defined as <asp:GridView ID="dataListings" runat="server" AllowSorting="True" AutoGenerateColumns="False" DataSourceID="LinqDataSource1" OnDataBinding="ListBox1_SelectedIndexChanged"> protected void ListBox1_SelectedIndexChanged(object sender, EventArgs e) { int itemSelected = selectTopics.SelectedIndex; string[] listing = null; switch (itemSelected)//assign listing the array of course numbers { case 0: break; case 1: listing = arts; break; case 2: listing = currentEvents; break; .... More cases here default: listing = arts; break; } using (OLLIDBDataContext odb = new OLLIDBDataContext()) { var q = from c in odb.tbl_CoursesAndWorkshops where listing.Contains(c.tbl_Course_Description.tbl_CoursesAndWorkshops.course_workshop_number) select c; dataListings.DataSource = q; dataListings.DataBind(); } } However, this method never gets fired. I can see a request being made when changing the selection, but setting a breakpoint at the method declaration does nothing at all. Based on this, setup, I have three related questions What do I need to modify to get the OnSelectionChanged event handler to fire? How can I alter the GridView area to be empty on page load? How do I send the results from the dataListings.DataBind() execution to show in the GridView?

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  • Where does abort() and terminate() "live"?

    - by user325016
    Regarding the terminate handler, As i understand it, when something bad happens in code, for example when we dont catch an exception, terminate() is called, which in turn calls abort() set_terminate(my_function) allows us to get terminate() to call a user specified function my_terminate. my question is: where do these functions "live" they don't seem to be a part of the language, but work as if they are present in every single cpp file, without having to include any header file.

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  • Qt - serialize/deserialaize text plus picture

    - by Narek
    I want to use a field (kind of QTextEdit), which is capabale of storing picture and text (like MS Word is doing) and it serializes and deserialaizes picture+text data. Is there any Qt Widget that allows us to manipulate with picture and text simultaniously and it has set/get functions which operate with serializable type? In othger words, I want to know if there exsists any Qt widget that can store picture+text and has "get" types of function that returns the content of that widgets editable area, which is a Type that could be serialized with QDataStream.

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  • Automatic profiling visual studio 2008

    - by phil
    Is there a way to do automatic profiling in visual studio 2008? I know how the profiling works both from the command line and using the GUI in VS08. What I want to accomplish: After my nightly build I want to complete some profiling (instrumental) to see if some functions (will most likely always be the same) have changed in some negative way (or positive of course).

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  • how wordpress can un-slug a title

    - by Mac Taylor
    i still , don't understand , how wordpress can understand what is this url refer to : www.mysite.com/about-me/ they are using no identifier if they using slug functions so how they can retain story information or in other word , how they change back the slugged title to select from database

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  • Rails: getting logic to run at end of request, regardless of filter chain aborts?

    - by JSW
    Is there a reliable mechanism discussed in rails documentation for calling a function at the end of the request, regardless of filter chain aborts? It's not after filters, because after filters don't get called if any prior filter redirected or rendered. For context, I'm trying to put some structured profiling/reporting information into the app log at the end of every request. This information is collected throughought the request lifetime via instance variables wrapped in custom controller accessors, and dumped at the end in a JSON blob for use by a post-processing script. My end goal is to generate reports about my application's logical query distribution (things that depend on controller logic, not just request URIs and parameters), performance profile (time spent in specific DB queries or blocked on webservices), failure rates (including invalid incoming requests that get rejected by before_filter validation rules), and a slew of other things that cannot really be parsed from the basic information in the application and apache logs. At a higher level, is there a different "rails way" that solves my app profiling goal?

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  • Is Java serialization a tool to shrink the memory footprint?

    - by Pentius
    Hey folks, does serialization in Java always have to shrink the memory that is used to hold an object structure? Or is it likely that serialization will have higher costs? In other words: Is serialization a tool to shrink the memory footprint of object structures in Java? Edit I'm totally aware of what serialization was intended for, but thanks anyway :-) But you know, tools can be misused. My question is, whether it is a good tool to decrease the memory usage. So what reasons can you imagine, why memory usage should increase/decrease? What will happen in most cases?

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  • Rendering inconsistencies in Internet Explorer

    - by gmunk
    Hello, I have some weird problem in rendering some xhtml in IE 8 http://img709.imageshack.us/i/scrj.png/. Here is the screenshot. As shown the greet me submit button is higher than the text field. Which is kind of odd. I checked with some other browsers and it works fine, it also works fine on Windows 7 with IE 8. Here is the code for the site: http://pastebin.com/cUkVA1HP http://pastebin.com/nU4cdpDE and the reset I'm using http://pastebin.com/uyEbAsEF I'm really puzzled by this strange behaviour. Thanks in advance for any ideas.

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