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• Securely store a password in program code?

  - by Nick

  My application makes use of the RijndaelManaged class to encrypt data. As a part of this encryption, I use a SecureString object loaded with a password which get's get converted to a byte array and loaded into the RajindaelManaged object's Key at runtime. The question I have is the storage of this SecureString. A user entered password can be entered at run-time, and that can be "securely" loaded into a SecureString object, but if no user entered password is given, then I need to default to something. So ultimately the quesiton comes down to: If I have to have some known string or byte array to load into a SecureString object each time my application runs, how do I do that? The "encrypted" data ultimately gets decrypted by another application, so even if no user entered password is specified, I still need the data to be encrypted while it goes from one app to another. This means I can't have the default password be random, because the other app wouldn't be able to properly decrypt it. One possible solution I'm thinking is to create a dll which only spits out a single passphrase, then I use that passphrase and run it through a couple of different hashing/reorganizing functions at runtime before I ultimately feed it into the secureString object. Would this be secure enough?

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• C# - Alternative to System.Time.Timer, to call a function at a specific time.

  - by Fábio Antunes

  Hello everybody. I want to call a specific function on my C# application at a specific time. At first i thought about using a Timer (System.Time.Timer), but that soon became impossible to use. Why? Simple. The Timer Class requires a Interval in milliseconds, but considering that i might want the function to be executed, lets says in a week that would mean: 7 Days = 168 hours; 168 Hours = 10,080 minutes; 10,080 Minutes = 6,048,000 seconds; 6,048,000 Seconds = 6,048,000,000 milliseconds; So the Interval would be 6,048,000,000; Now lets remember that the Interval accepted data type is int, and as we know int range goes from -2,147,483,648 to 2,147,483,647. That makes Timer useless in this case once we cannot set a Interval bigger that 2,147,483,647 milliseconds. So i need a solution where i could specify when the function should be called. Something like this: solution.ExecuteAt = "30-04-2010 15:10:00"; solution.Function = "functionName"; solution.Start(); So when the System Time would reach "30-04-2010 15:10:00" the function would be executed in the application. How can this problem be solved? Thanks just by taking the time to read my question. But if you could provide me with some help i would be most grateful. Additional Info: What these functions will do? Getting climate information and based on that info: Starting / Shutting down other Applications (most of them Console Based); Sending custom Commands to those Console Applications; Power down, Rebooting, Sleep, Hibernate the computer; And if possible schedule the BIOS to Power Up the Computer;

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• refactor LINQ TO SQL custom properties that instantiate datacontext

  - by Thiago Silva

  I am working on an existing ASP.NET MVC app that started small and has grown with time to require a good re-architecture and refactoring. One thing that I am struggling with is that we've got partial classes of the L2S entities so we could add some extra properties, but these props create a new data context and query the DB for a subset of data. This would be the equivalent to doing the following in SQL, which is not a very good way to write this query as oppsed to joins: SELECT tbl1.stuff, (SELECT nestedValue FROM tbl2 WHERE tbl2.Foo = tbl1.Bar), tbl1.moreStuff FROM tbl1 so in short here's what we've got in some of our partial entity classes: public partial class Ticket { public StatusUpdate LastStatusUpdate { get { //this static method call returns a new DataContext but needs to be refactored var ctx = OurDataContext.GetContext(); var su = Compiled_Query_GetLastUpdate(ctx, this.TicketId); return su; } } } We've got some functions that create a compiled query, but the issue is that we also have some DataLoadOptions defined in the DataContext, and because we instantiate a new datacontext for getting these nested property, we get an exception "Compiled Queries across DataContexts with different LoadOptions not supported" . The first DataContext is coming from a DataContextFactory that we implemented with the refactorings, but this second one is just hanging off the entity property getter. We're implementing the Repository pattern in the refactoring process, so we must stop doing stuff like the above. Does anyone know of a good way to address this issue?

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• Boost.Python wrapping hierarchies avoiding diamond inheritance

  - by stbuton

  I'm having some trouble seeing what the best way to wrap a series of classes with Boost.Python while avoiding messy inheritance problems. Say I have the classes A, B, and C with the following structure: struct A { virtual void foo(); virtual void bar(); virtual void baz(); }; struct B : public A { virtual void quux(); }; struct C : public A { virtual void foobar(); }; I want to wrap all classes A, B, and C such that they are extendable from Python. The normal method for accomplishing this would be along the lines of: struct A_Wrapper : public A, boost::python::wrapper<A> { //dispatch logic for virtual functions }; Now for classes B and C which extend from A I would like to be able to inherit and share the wrapping implementation for A. So I'd like to be able to do something along the lines of: struct B_Wrapper : public B, public A_Wrapper, public boost::python::wrapper<B> { //dispatch logic specific for B }; struct C_Wrapper : public C, public A_Wrapper, public boost::python::wrapper<C> { //dispatch logic specific for C } However, it seems like that would introduce all manner of nastiness with the double inheritance of the boost wrapper base and the double inheritance of A in the B_Wrapper and C_Wrapper objects. Is there a common way that this instance is solved that I'm missing? thanks.

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• Checking for Repeated Strings in 2d list

  - by Zach Santiago

  i have a program where i have a list of names and classes. i have the list in alphabetical order. now im trying to check if names repeat, add the classes to one single name. im trying to write some code like go through names if name is already in list, add the class to the one name. so an example would be, instead of having 'Anita ','phys 1443', and 'Anita','IE 3312' i would just have 'Anita','PHYS 1443','IE 3312'. How would i go about doing this in a logival way, WITHOUT using any sort of built in functions? i tried comparing indexe's like if list[i][0] == list[i+1][0], append list[i+1][1] to an emptylist. while that almost worked, it would screw up at some points along the way. here is my attempt size = len(c) i = 0 c = [['Anita', 'PHYS 1443'], ['Anita', 'IE 3312'], ['Beihuang', 'PHYS 1443'], ['Chiao-Lin', 'MATH 1426'], ['Chiao-Lin', 'IE 3312'], ['Christopher', 'CSE 1310'], ['Dylan', 'CSE 1320'], ['Edmund', 'PHYS 1443'], ['Ian', 'IE 3301'], ['Ian', 'CSE 1320'], ['Ian', 'PHYS 1443'], ['Isis', 'PHYS 1443'], ['Jonathan', 'MATH 2325'], ['Krishna', 'MATH 2325'], ['Michael', 'IE 3301'], ['Nang', 'MATH 2325'], ['Ram', 'CSE 1320'], ['Taesu', 'CSE 1320'], ["Tre'Shaun", 'IE 3312'], ["Tre'Shaun", 'MATH 2325'], ["Tre'Shaun", 'CSE 1310']] ## Check if any names repeat d.append(c[0][0]) while i < size - 1 : if c[i][0] == c[i+1][0] : d.append(c[i][1]) d.append(c[i+1][1]) else : d.append(c[i+1][0]) d.append(c[i+1][1]) i = i + 1 print d output was. ['Anita', 'PHYS 1443', 'IE 3312', 'Beihuang', 'PHYS 1443', 'Chiao-Lin', 'MATH 1426', 'MATH 1426', 'IE 3312', 'Christopher', 'CSE 1310', 'Dylan', 'CSE 1320', 'Edmund', 'PHYS 1443', 'Ian', 'IE 3301', 'IE 3301', 'CSE 1320', 'CSE 1320', 'PHYS 1443', 'Isis', 'PHYS 1443', 'Jonathan', 'MATH 2325', 'Krishna', 'MATH 2325', 'Michael', 'IE 3301', 'Nang', 'MATH 2325', 'Ram', 'CSE 1320', 'Taesu', 'CSE 1320', "Tre'Shaun", 'IE 3312', 'IE 3312', 'MATH 2325', 'MATH 2325', 'CSE 1310']

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• Python metaclass for enforcing immutability of custom types

  - by Mark Lehmacher

  Having searched for a way to enforce immutability of custom types and not having found a satisfactory answer I came up with my own shot at a solution in form of a metaclass: class ImmutableTypeException( Exception ): pass class Immutable( type ): ''' Enforce some aspects of the immutability contract for new-style classes: - attributes must not be created, modified or deleted after object construction - immutable types must implement __eq__ and __hash__ ''' def __new__( meta, classname, bases, classDict ): instance = type.__new__( meta, classname, bases, classDict ) # Make sure __eq__ and __hash__ have been implemented by the immutable type. # In the case of __hash__ also make sure the object default implementation has been overridden. # TODO: the check for eq and hash functions could probably be done more directly and thus more efficiently # (hasattr does not seem to traverse the type hierarchy) if not '__eq__' in dir( instance ): raise ImmutableTypeException( 'Immutable types must implement __eq__.' ) if not '__hash__' in dir( instance ): raise ImmutableTypeException( 'Immutable types must implement __hash__.' ) if _methodFromObjectType( instance.__hash__ ): raise ImmutableTypeException( 'Immutable types must override object.__hash__.' ) instance.__setattr__ = _setattr instance.__delattr__ = _delattr return instance def __call__( self, *args, **kwargs ): obj = type.__call__( self, *args, **kwargs ) obj.__immutable__ = True return obj def _setattr( self, attr, value ): if '__immutable__' in self.__dict__ and self.__immutable__: raise AttributeError( "'%s' must not be modified because '%s' is immutable" % ( attr, self ) ) object.__setattr__( self, attr, value ) def _delattr( self, attr ): raise AttributeError( "'%s' must not be deleted because '%s' is immutable" % ( attr, self ) ) def _methodFromObjectType( method ): ''' Return True if the given method has been defined by object, False otherwise. ''' try: # TODO: Are we exploiting an implementation detail here? Find better solution! return isinstance( method.__objclass__, object ) except: return False However, while the general approach seems to be working rather well there are still some iffy implementation details (also see TODO comments in code): How do I check if a particular method has been implemented anywhere in the type hierarchy? How do I check which type is the origin of a method declaration (i.e. as part of which type a method has been defined)?

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• Invalidating Memcached Keys on save() in Django

  - by Zack

  I've got a view in Django that uses memcached to cache data for the more highly trafficked views that rely on a relatively static set of data. The key word is relatively: I need invalidate the memcached key for that particular URL's data when it's changed in the database. To be as clear as possible, here's the meat an' potatoes of the view (Person is a model, cache is django.core.cache.cache): def person_detail(request, slug): if request.is_ajax(): cache_key = "%s_ABOUT_%s" % settings.SITE_PREFIX, slug # Check the cache to see if we've already got this result made. json_dict = cache.get(cache_key) # Was it a cache hit? if json_dict is None: # That's a negative Ghost Rider person = get_object_or_404(Person, display = True, slug = slug) json_dict = { 'name' : person.name, 'bio' : person.bio_html, 'image' : person.image.extra_thumbnails['large'].absolute_url, } cache.set(cache_key) # json_dict will now exist, whether it's from the cache or not response = HttpResponse() response['Content-Type'] = 'text/javascript' response.write(simpljson.dumps(json_dict)) # Make sure it's all properly formatted for JS by using simplejson return response else: # This is where the fully templated response is generated What I want to do is get at that cache_key variable in it's "unformatted" form, but I'm not sure how to do this--if it can be done at all. Just in case there's already something to do this, here's what I want to do with it (this is from the Person model's hypothetical save method) def save(self): # If this is an update, the key will be cached, otherwise it won't, let's see if we can't find me try: old_self = Person.objects.get(pk=self.id) cache_key = # Voodoo magic to get that variable old_key = cache_key.format(settings.SITE_PREFIX, old_self.slug) # Generate the key currently cached cache.delete(old_key) # Hit it with both barrels of rock salt # Turns out this doesn't already exist, let's make that first request even faster by making this cache right now except DoesNotExist: # I haven't gotten to this yet. super(Person, self).save() I'm thinking about making a view class for this sorta stuff, and having functions in it like remove_cache or generate_cache since I do this sorta stuff a lot. Would that be a better idea? If so, how would I call the views in the URLconf if they're in a class?

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• Java Robot key activity seems to stop working while certain software is running

  - by Mike Turley

  I'm writing a Java application to automate character actions in an online game overnight (specifically, it catches fish in Final Fantasy XI). The app makes heavy use of java's Robot class both for emulating user keyboard input and for detecting color changes on certain parts of the screen. It also uses multithreading and a swing GUI. The application seems to work perfectly when I test it without the game running, just using screenshots to trigger the apps responses into notepad. But for some reason, when I actually launch FFXI and start the program, all of my keyboard and mouse manipulations just stop working altogether. The program is still running, and the Robot class is still able to read pixel colors. But Robot.keyPress, Robot.keyRelease, Robot.mouseMove, Robot.mousePress and Robot.mouseRelease all do nothing. It's the strangest thing-- to test it, I wrote a simple loop that just keeps typing letters, and focused notepad. I'd then start the game, refocus notepad, and it would do nothing. Then I'd exit the game, and it'd start working again immediately. Has anyone else come across something like this, where specific software will stop certain functions of java from working? Also, to make this more interesting-- Last year I wrote a very similar program using the same classes and programming techniques to automate healing a party in the game as they fight. Last year, this program worked perfectly. After running into these problems I dug up that old program, ran it without making any changes, and found that it too was having the same problems. The only differences between now and when it was working: I was running Windows Vista and now I'm running Windows 7, and several new Java versions as well as FFXI versions have been released. What the hell is going on? (if anyone needs to see my source code, email me at [email protected]. I'm trying to keep it to myself.)

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• unable to use turboc through xp. why? solution?

  - by Fizz

  hi, im having problems opening directly turboc++ compiler(dos version) on xp. if i d-click on the tc icon through windows gui it opens for a sec(a blank dos screen) and shuts down. so i hv to acces through cmd and then adress of turboc and tc i.e., cmd (enter) c:\tc\bin (enter) tc.exe this way tc opens and im able to program all text programming.. why do i have to always start tc through dos..why can't i start it through xp. also,after starting tc through dos, im unable to execute any graphics program through it.. i write a simple code for creating a circle using predefined functions.. all directories have been set as per req. when i compile and run the prog. tc exits and returns to dos cmd prompt. why does this happen? solution? i hv also tried using dos box to run turboc. it closes automatically on executing the grapics program.. plzz help...

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• UnsatisfiedLinkError: The specified procedure could not be found

  - by matt

  I'm writing some JNI code in C++ to be called from an applet on Windows XP. I've been able to successfully run the applet and have the JNI library loaded and called, even going so far as having it call functions in other DLLs. I got this working by setting up the PATH system environment variable to include the directory all of my DLLs are in. So, the problem, is that I add another call that uses a new external DLL, and suddenly when loading the library, an UnsatisfiedLinkError is thrown. The message is: 'The specified procedure could not be found'. This doesn't seem to be a problem with a missing dependent DLL, because I can remove a dependent DLL and get a different message about dependent DLL missing. From what I've been able to find online, it appears that this message means that a native Java function implementation is missing from the DLL, but it's odd that it works fine without this extra bit of code. Does anyone know what might be causing this? What kinds of things can give a 'The specified procedure could not be found' messages for an UnsatisifedLinkError?

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• Question about functional OOP style in JavaScript

  - by valums

  I prefer to use functional OOP style for my code (similar to the module pattern) because it helps me to avoid the "new" keyword and all problems with the scope of "this" keyword in callbacks. But I've run into a few minor issues with it. I would like to use the following code to create a class. namespace.myClass = function(){ var self = {}, somePrivateVar1; // initialization code that would call // private or public methods privateMethod(); self.publicMethod(); // sorry, error here function privateMethod(){} self.publicMethod = function(){}; return self; } The problem is that I can't call public methods from my initialization code, as these functions are not defined yet. The obvious solution would be to create an init method, and call it before "return self" line. But maybe you know a more elegant solution? Also, how do you usually handle inheritance with this pattern? I use the following code, butI would like to hear your ideas and suggestions. namespace.myClass2 = function(){ var self = namespace.parentClass(), somePrivateVar1; var superMethod = self.someMethod; self.someMethod = function(){ // example shows how to overwrite parent methods superMethod(); }; return self; } Edit. For those who asked what are the reasons for choosing this style of OOP, you can look into following questions: http://stackoverflow.com/questions/1557386/prototypal-vs-functional-oop-in-javascript http://stackoverflow.com/questions/383402/is-javascript-s-new-keyword-considered-harmful

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• Save email as draft in php

  - by Yorian

  Hello, The past few days I've been trying to find out how I can save emails as drafts using php. I've created an emailaddress that uses imap (and resides on the same server). What I would like to do is to use php to create an email and store it in the drafts folder. These emails would then be recognized by the email client (ms office outlook in this case) so they can be editted and send from the email client. I've found some interesting information about the imap functions from php, they let you send mail, but I can't really figure out how to store them in the drafts folder (to which I have write access). I can actually find and read the emails, I save as drafts in my email client, using my ftp connection. However they make use of UID and message-ID's and such which I don't understand where they come from. My questions: - how could I create email drafts - How does a new UID or message-ID get created, and how would I use them for my email-draft file? Help is much appreciated, thanks. Yorian

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• OpenGL bitmap text fails after drawing polygon

  - by kaykun

  I'm using Win32 and OpenGL to to draw text onto a window. I'm using the bitmap font method, with wglUseFontBitmaps. Here is my main rendering function: glClear(GL_COLOR_BUFFER_BIT); glPushMatrix(); glColor3f(1.0f, 0.0f, 1.0f); glBegin(GL_QUADS); glVertex2f(0.0f, 0.0f); glVertex2f(128.0f, 0.0f); glVertex2f(128.0f, 128.0f); glVertex2f(0.0f, 128.0f); glEnd(); glPopMatrix(); glPushMatrix(); glColor3f(1.0f, 1.0f, 1.0f); glRasterPos2i(200, 200); glListBase(fontList); glCallLists(5, GL_UNSIGNED_BYTE, "Test."); glPopMatrix(); SwapBuffers(hDC); As you can see it's very simple and the only thing that it's supposed to do is draw a quadrilateral and draw the text "Test.". But the problem is that drawing a polygon seems to mess up any text operations I try to do after it. If I place the text drawing functions before the polygon, both the text and the polygon draw fine. Is there something I'm missing here? Edit: This problem only happens when the window is run in Fullscreen, by ChangeDisplaySettings. Any reason why this would be??

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• Templates vs. coded HTML

  - by Alan Harris-Reid

  I have a web-app consisting of some html forms for maintaining some tables (SQlite, with CherryPy for web-server stuff). First I did it entirely 'the Python way', and generated html strings via. code, with common headers, footers, etc. defined as functions in a separate module. I also like the idea of templates, so I tried Jinja2, which I find quite developer-friendly. In the beginning I thought templates were the way to go, but that was when pages were simple. Once .css and .js files were introduced (not necessarily in the same folder as the .html files), and an ever-increasing number of {{...}} variables and {%...%} commands were introduced, things started getting messy at design-time, even though they looked great at run-time. Things got even more difficult when I needed additional javascript in the or sections. As far as I can see, the main advantages of using templates are: Non-dynamic elements of page can easily be viewed in browser during design. Except for {} placeholders, html is kept separate from python code. If your company has a web-page designer, they can still design without knowing Python. while some disadvantages are: {{}} delimiters visible when viewed at design-time in browser Associated .css and .js files have to be in same folder to see effects in browser at design-time. Data, variables, lists, etc., must be prepared in advanced and either declared globally or passed as parameters to render() function. So - when to use 'hard-coded' HTML, and when to use templates? I am not sure of the best way to go, so I would be interested to hear other developers' views. TIA, Alan

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• How can I write classes that don't rely on "global" variables?

  - by Joel

  When I took my first programming course in university, we were taught that global variables were evil & should be avoided at all cost (since you can quickly develop confusing and unmaintainable code). The following year, we were taught object oriented programming, and how to create modular code using classes. I find that whenever I work with OOP, I use my classes' private variables as global variables, i.e., they can be (and are) read and modified by any function within the class. This isn't really sitting right with me, as it seems to introduce the same problems global variables had in languages like C. So I guess my question is, how do I stop writing classes with "global" variables? Would it make more sense to pretend I'm writing in a functional language? By this I mean having all functions take parameters & return values instead of directly modifying class variables. If I need to set any fields, I can just take the output of the function and assign it instead of having the function do it directly. This seems like it might make more maintainable code, at least for larger classes. What's common practice? Thanks!

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• What is a good standard exercise to learn the OO features of a language?

  - by FarmBoy

  When I'm learning a new language, I often program some mathematical functions to get used to the control flow syntax. After that, I like to implement some sorting algorithms to get used to the array/list constructs. But I don't have a standard exercise for exploring the languages OO features. Does anyone have a stock exercise for this? A good answer would naturally lend to inheritance, polymorphism, etc., for a programmer already comfortable with these concepts. An ideal answer would be one that could be communicated in a few words, without ambiguity, in the way that "implement mergesort" is completely unambiguous. (As an example, answering "design a game" is so vague as to be useless.) Any ideas? EDIT: I have to remark that the results here are somewhat ironic. 10 upvotes and (originally) 5 favorites suggest that this is a question others are interested in. Yet the most upvoted answer is one that says there is no good answer. Oh well. I think I'll look at the textbook below, I've found games useful in the past for OO.

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• Calculating odds distribution with 6-sided dice

  - by Stephen

  I'm trying to calculate the odds distribution of a changing number of 6-sided die rolls. For example, 3d6 ranges from 3 to 18 as follows: 3:1, 4:3, 5:6, 6:10, 7:15, 8:21, 9:25, 10:27, 11:27, 12:25, 13:21, 14:15, 15:10, 16:6, 17:3, 18:1 I wrote this php program to calculate it: function distributionCalc($numberDice,$sides=6) { for ( $i=0; $i<pow($sides,$numberDice); $i++) { $sum=0; for ($j=0; $j<$numberDice; $j++) { $sum+=(1+(floor($i/pow($sides,$j))) % $sides); } $distribution[$sum]++; } return $distribution; } The inner $j for-loop uses the magic of the floor and modulus functions to create a base-6 counting sequence with the number of digits being the number of dice, so 3d6 would count as: 111,112,113,114,115,116,121,122,123,124,125,126,131,etc. The function takes the sum of each, so it would read as: 3,4,5,6,7,8,4,5,6,7,8,9,5,etc. It plows through all 3^6 possible results and adds 1 to the corresponding slot in the $distribution array between 3 and 18. Pretty straightforward. However, it only works until about 8d6, afterward i get server time-outs because it's now doing billions of calculations. But I don't think it's necessary because die probability follows a sweet bell-curve distribution. I'm wondering if there's a way to skip the number crunching and go straight to the curve itself. Is there a way to do this, so, for example, with 80d6 (80-480)? Can the distribution be projected without doing 6^80 calculations? I'm not a professional coder and probability is still new to me, so thanks for all the help! Stephen

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• Suggest joomla html editor extension/software

  - by DMin

  I've started using Joomla 1.5 recently and am using the TinyMCE online WYSIWYG editor that comes with the package to edit articles. I tend to write direct html and javascript rather than use the WYSIWYG functions, I find that after the first time the changes are applied(page updated) most of your html becomes 4-5 separate big paragraphs. Its very hard to find stuff in there cause the content has no formatting -- eg: <p><span id="psy_ass_span" class="pink_heading">Psychometric Assessment</span></p> <div id="psy_ass_div" class="pink_box"><img class="img_right" src="templates/teamwork.jpg" border="0" /> <p><strong>Emporkommen</strong> uses <strong>Psychometric assessment</strong> as a tool in order to gain insight into a person’s personality and psychological thinking. It can help develop team spirit in t <script src="plugins/editors/tinymce/jscripts/tiny_mce/themes/advanced/langs/en.js" type="text/javascript"></script> he workplace and assess an individual’s priorities.</p> Plus obviously there is no code highlighting in the editor so you can't figure out what is what. My question is, do you guys know of good(preferably non-commercial) extensions or other softwares or techniques that can make editing html code in Joomla 1.5 articles easier even after applying changes several times.

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• Haskell Linear Algebra Matrix Library for Arbitrary Element Types

  - by Johannes Weiß

  I'm looking for a Haskell linear algebra library that has the following features: Matrix multiplication Matrix addition Matrix transposition Rank calculation Matrix inversion is a plus and has the following properties: arbitrary element (scalar) types (in particular element types that are not Storable instances). My elements are an instance of Num, additionally the multiplicative inverse can be calculated. The elements mathematically form a finite field (??2256). That should be enough to implement the features mentioned above. arbitrary matrix sizes (I'll probably need something like 100x100, but the matrix sizes will depend on the user's input so it should not be limited by anything else but the memory or the computational power available) as fast as possible, but I'm aware that a library for arbitrary elements will probably not perform like a C/Fortran library that does the work (interfaced via FFI) because of the indirection of arbitrary (non Int, Double or similar) types. At least one pointer gets dereferenced when an element is touched (written in Haskell, this is not a real requirement for me, but since my elements are no Storable instances the library has to be written in Haskell) I already tried very hard and evaluated everything that looked promising (most of the libraries on Hackage directly state that they wont work for me). In particular I wrote test code using: hmatrix, assumes Storable elements Vec, but the documentation states: Low Dimension : Although the dimensionality is limited only by what GHC will handle, the library is meant for 2,3 and 4 dimensions. For general linear algebra, check out the excellent hmatrix library and blas bindings I looked into the code and the documentation of many more libraries but nothing seems to suit my needs :-(. Update Since there seems to be nothing, I started a project on GitHub which aims to develop such a library. The current state is very minimalistic, not optimized for speed at all and only the most basic functions have tests and therefore should work. But should you be interested in using or helping out developing it: Contact me (you'll find my mail address on my web site) or send pull requests.

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• Write binary data as a response in an ASP.NET MVC web control

  - by Lou Franco

  I am trying to get a control that I wrote for ASP.NET to work in an ASP.NET MVC environment. Normally, the control does the normal thing, and that works fine Sometimes it needs to respond by clearing the response, writing an image to the response stream and changing the content type. When you do this, you get an exception "OutputStream is not available when a custom TextWriter is used". If I were a page or controller, I see how I can create custom responses with binary data, but I can't see how to do this from inside a control's render functions. To simplify it -- imagine I want to make a web control that renders to: <img src="pageThatControlIsOn?controlImage"> And I know how to look at incoming requests and recognize query strings that should be routed to the control. Now the control is supposed to respond with a generated image (content-type: image/png -- and the encoded image). In ASP.NET, we: Response.Clear(); Response.OutputStream.Write(thePngData); // this throws in MVC // set the content type, etc Response.End(); How am I supposed to do that in an ASP.NET MVC control?

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• When does it makes sense to use a map?

  - by kiwicptn

  I am trying to round up cases when it makes sense to use a map (set of key-value entries). So far I have five categories (see below). Assuming more exist, what are they? Please limit each answer to one unique category, put up an example, and vote up the fascinating ones. Property values (like a bean) age -> 30 sex -> male loc -> calgary Histograms peter -> 1 john -> 7 paul -> 5 Presence, with O(1) performance peter -> 1 john -> 1 paul -> 1 Functions peter -> treatPeter() john -> dealWithJohn() paul -> managePaul() Conversion peter -> pierre john -> jean paul -> paul

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• Locking semaphores in C problem sys/sem

  - by Vojtech R.

  Hi, I have problem with my functions. Sometimes two processes enter into critical section. I can't find problem in this after I spent 10 hours by debugging. On what I should aim? // lock semaphore static int P(int sem_id) { struct sembuf sem_b; sem_b.sem_num = 0; sem_b.sem_op = -1; /* P() */ sem_b.sem_flg = 0; if (semop(sem_id, &sem_b, 1) == -1) { print_error("semop in P", errno); return(0); } return(1); } // unlock semaphore static int V(int sem_id) { struct sembuf sem_b[1]; sem_b.sem_num = 0; sem_b.sem_op = 1; /* V() */ sem_b.sem_flg = 0; if (semop(sem_id, &sem_b, 1) == -1) { print_error("semop in V", errno); return(0); } return(1); } The action loop: int mutex; if ((mutex=semget(key, 1, 0666))>=0) { // semaphore exists } while(1) { P(mutex); assert(get_val(mutex)==0); (*action)++; V(mutex); } Many thanks

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• Find and Replace RegEx with wildcard search and addition of value

  - by fraXis

  The below code is from my other questions that I have asked here on SO. Everyone has been so helpful and I almost have a grasp with regards to RegEx but I ran into another hurdle. This is what I basically need to do in a nutshell. I need to take this line that is in a text file that I load into my content variable: X17.8Y-1.Z0.1G0H1E1 I need to do a wildcard search for the X value, Y value, Z value, and H value. When I am done, I need this written back to my text file (I know how to create the text file so that is not the problem). X17.8Y-1.G54G0T2 G43Z0.1H1M08 I have code that the kind users here have given me, except I need to create the T value at the end of the first line, and use the value from the H and increment it by 1 for the T value. For example: X17.8Y-1.Z0.1G0H5E1 would translate as: X17.8Y-1.G54G0T6 G43Z0.1H5M08 The T value is 6 because the H value is 5. I have code that does everything (does two RegEx functions and separates the line of code into two new lines and adds some new G values). But I don't know how to add the T value back into the first line and increment it by 1 of the H value. Here is my code: StreamReader reader = new StreamReader(fDialog.FileName.ToString()); string content = reader.ReadToEnd(); reader.Close(); content = Regex.Replace(content, @"X[-\d.]+Y[-\d.]+", "$0G54G0"); content = Regex.Replace(content, @"(Z(?:\d*\.)?\d+)[^H]*G0(H(?:\d*\.)?\d+)\w*", "\nG43$1$2M08"); //This must be created on a new line This code works great at taking: X17.8Y-1.Z0.1G0H5E1 and turning it into: X17.8Y-1.G54G0 G43Z0.1H5M08 but I need it turned into this: X17.8Y-1.G54G0T6 G43Z0.1H5M08 (notice the T value is added to the first line, which is the H value +1 (T = H + 1). Can someone please modify my RegEx statement so I can do this automatically? I tried to combine my two RegEx statements into one line but I failed miserably.

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• is this valid json array using php

  - by Rich

  Hello, I need to convert some code done by someone else, to work in my mvc model It is using some functions like EOD that I don't understand. Does that still work in a class? Primarely, my question focusus on the json output. The old code does not use the php json_encode function, but outputs it directly like this ?> { "username": "<?php echo $_SESSION['username'];?>", "items": [ <?php echo $items;?> ] } <?php I would do it like this, but I need to be sure it's right for the items part header('Content-type: application/json'); $output = array("username"=> isset( $_SESSION['username'] ) ? $_SESSION['username'] : "?", "items"=>$items ); $this->content = json_encode($output); This is some background on how the $items is made. An item is stored like this: $_SESSION['chatHistory'][$_POST['to']] .= <<<EOD { "s": "1", "f": "{$to}", "m": "{$messagesan}" }, EOD; and it is put in the $items variable like this $items = ''; if ( !empty($_SESSION['openChatBoxes'] ) ) { foreach ( $_SESSION['openChatBoxes'] as $chatbox => $void ) { $items .= $this->chatBoxSession($chatbox); } } //The chatBoxSession() function takes an item from the $_SESSION['chatHistory'] array and returns it. I hope this was somewhat clear enough? The php manual warns that in some cases you don't get an array output, instead you get an object. So, with the EOD syntax, I am not really sure. It could save me some time if I know some things are doing what they supposed too, and giving the right output. thanks, Richard

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• Curve fitting: Find the smoothest function that satisfies a list of constraints.

  - by dreeves

  Consider the set of non-decreasing surjective (onto) functions from (-inf,inf) to [0,1]. (Typical CDFs satisfy this property.) In other words, for any real number x, 0 <= f(x) <= 1. The logistic function is perhaps the most well-known example. We are now given some constraints in the form of a list of x-values and for each x-value, a pair of y-values that the function must lie between. We can represent that as a list of {x,ymin,ymax} triples such as constraints = {{0, 0, 0}, {1, 0.00311936, 0.00416369}, {2, 0.0847077, 0.109064}, {3, 0.272142, 0.354692}, {4, 0.53198, 0.646113}, {5, 0.623413, 0.743102}, {6, 0.744714, 0.905966}} Graphically that looks like this: We now seek a curve that respects those constraints. For example: Let's first try a simple interpolation through the midpoints of the constraints: mids = ({#1, Mean[{#2,#3}]}&) @@@ constraints f = Interpolation[mids, InterpolationOrder->0] Plotted, f looks like this: That function is not surjective. Also, we'd like it to be smoother. We can increase the interpolation order but now it violates the constraint that its range is [0,1]: The goal, then, is to find the smoothest function that satisfies the constraints: Non-decreasing. Tends to 0 as x approaches negative infinity and tends to 1 as x approaches infinity. Passes through a given list of y-error-bars. The first example I plotted above seems to be a good candidate but I did that with Mathematica's FindFit function assuming a lognormal CDF. That works well in this specific example but in general there need not be a lognormal CDF that satisfies the constraints.

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