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• Accessing appropriate array of double arrays in order of last created.

  - by Zach

  I have an array of double arrays, they are within a specified time window (8am-5pm), and are in order of last created over a period of several days. They are all timestamped and as such I have access to all C# DateTime methods. I then have a different iterative function that goes in the same order of the array of double arrays, however it isn't within a specified time window, it's 24/7. I want to access from this iterative function, the appropriate double array from the one within the window. Let's say that it's 4:30PM on DayOfYear 52, I'd like to access the last double array less than or equal to 4:30PM on DayOfYear 52. I'd expect the same double array if the time were 12:30AM on DayOfYear 53. However, if it were 9:00 AM of DayOfYear 53, well then I'd expect it to return something from the DayOfYear 53, less than or equal to 9:00AM. I think you get the idea. So I'm a having a bit of trouble grokking how to do this. Is anyone willing to offer a starting point or how they'd approach it? Edit: It is not a literal double[][], it is exactly as Anthony Pegram says: Dictionary<DateTime, double[]>

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• How do I set up the python/c library correctly?

  - by Bartvbl

  I have been trying to get the python/c library to like my mingW compiler. The python online doncumentation; http://docs.python.org/c-api/intro.html#include-files only mentions that I need to import the python.h file. I grabbed it from the installation directory (as is required on the windows platform), and tested it by compiling the script: #include "Python.h". This compiled fine. Next, I tried out the snippet of code shown a bit lower on the python/c API page: PyObject *t; t = PyTuple_New(3); PyTuple_SetItem(t, 0, PyInt_FromLong(1L)); PyTuple_SetItem(t, 1, PyInt_FromLong(2L)); PyTuple_SetItem(t, 2, PyString_FromString("three")); For some reason, the compiler would compile the code if I'd remove the last 4 lines (so that only the pyObject variable definition would be left), yet calling the actual constructor of the tuple returned errors. I am probably missing something completely obvious here, given I am very new to C, but does anyone know what it is?

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• an algorhithm for filtering out raw txt files

  - by Roman Luštrik

  Imagine you have a .txt file of the following structure: >>> header >>> header >>> header K L M 200 0.1 1 201 0.8 1 202 0.01 3 ... 800 0.4 2 >>> end of file 50 0.1 1 75 0.78 5 ... I would like to read all the data except lines denoted by >>> and lines below the >>> end of file line. So far I've solved this using read.table(comment.char = ">", skip = x, nrow = y) (x and y are currently fixed). This reads the data between the header and >>> end of file. However, I would like to make my function a bit more plastic regarding the number of rows. Data may have values larger than 800, and consequently more rows. I could scan or readLines the file and see which row corresponds to the >>> end of file and calculate the number of lines to be read. What approach would you use?

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• How do I compare two PropertyInfos or methods reliably?

  - by Rob Ashton

  Same for methods too: I am given two instances of PropertyInfo or methods which have been extracted from the class they sit on via GetProperty or GetMember etc, (or from a MemberExpression maybe). I want to determine if they are in fact referring to the same Property or the same Method so (propertyOne == propertyTwo) or (methodOne == methodTwo) Clearly that isn't going to actually work, you might be looking at the same property, but it might have been extracted from different levels of the class hierarchy (in which case generally, propertyOne != propertyTwo) Of course, I could look at DeclaringType, and re-request the property, but this starts getting a bit confusing when you start thinking about Properties/Methods declared on interfaces and implemented on classes Properties/Methods declared on a base class (virtually) and overridden on derived classes Properties/Methods declared on a base class, overridden with 'new' (in IL world this is nothing special iirc) At the end of the day, I just want to be able to do an intelligent equality check between two properties or two methods, I'm 80% sure that the above bullet points don't cover all of the edge cases, and while I could just sit down, write a bunch of tests and start playing about, I'm well aware that my low level knowledge of how these concepts are actually implemented is not excellent, and I'm hoping this is an already answered topic and I just suck at searching. The best answer would give me a couple of methods that achieve the above, explaining what edge cases have been taken care of and why :-)

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• Is it possible to customize @synthesized properties?

  - by Dan K.

  I'm probably just being a bit lazy here, but bear with me. Here's my situation. I have a class with two nonatomic, retained properties. Let's say: @property (nonatomic, retain) UITextField *dateField; @property (nonatomic, retain) NSDate *date; I synthesize them as expected in the implementation. What I want to happen is that whenever the setter on date is invoked, it also does something to the dateField (i.e. it sets the text property on the dateField to be a nicely formatted version of the date). I realize I can just manually override the setter for date in my implementation by doing the following: - (void) setDate:(NSDate *)newDate { if (date != newDate) { [date release]; date = [newDate retain]; // my code to touch the dateField goes here } } What would be awesome is if I could let Objective C handle the retain/release cycle, but still be able to "register" (for lack of a better term) a custom handler that would be invoked after the retain/release/set happens. My guess is that isn't possible. My google-fu didn't come up with any answer to this, though, so I thought I'd ask.

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• problem with a very simple tile based game

  - by newbieguy

  Hello, I am trying to create a pacman-like game. I have an array that looks like this: array: 1111111111111 1000000000001 1111110111111 1000000000001 1111111111111 1 = Wall, 0 = Empty space I use this array to draw tiles that are 16x16 in size. The Game character is 32x32. Initially I represented the character's position in array indexes, [1,1] etc. I would update his position if array[character.new_y][charater.new_x] == 0 Then I translated these array coordinates to pixels, [y*16, x*16] to draw him. He was lining up nicely, wouldn't go into walls, but I noticed that since I was updating him by 16 pixels each, he was moving very fast. I decided to do it in reverse, to store the game character's position in pixels instead, so that he could use less than 16 pixels per move. I thought that a simple if statement such as this: if array[(character.new_pixel_y)/16][(character.new_pixel_x)/16] == 0 would prevent him from going into walls, but unfortunately he eats a bit of the bottom and right side walls. Any ideas how would I properly translate pixel position to the array indexes? I guess this is something simple, but I really can't figure it out :(

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• Javascript style variables with "-" in their name aren't able to be changed?

  - by William

  Okay, so this bug has cost me quite a bit of time and embarrassment. It seems that any style variable with a - in it's name can't be modified by javascript. As seen here: <!DOCTYPE html> <html lang="en"> <head> <title>Class Test</title> <meta charset="utf-8" /> <style> body { text-align: center; background-color: #ffffff;} #box { position: absolute; left: 610px; top: 80px; height: 50px; width: 50px; background-color: #ff0000; color: #000000;} </style> <script type="text/javascript"> var box = 0; </script> </head> <body> <div id="box" ></div> <script type="text/javascript"> box = document.getElementById('box'); box.style.background-color = "#0000ff"; </script> </body> </html> The box in said example will just remain red. So how do I change a style variable with a - in it's name?

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• Most efficient way of checking if Date object and Calendar object are in the same month

  - by Indigenuity

  I am working on a project that will run many thousands of comparisons between dates to see if they are in the same month, and I am wondering what the most efficient way of doing it would be. This isn't exactly what my code looks like, but here's the gist: List<Date> dates = getABunchOfDates(); Calendar month = Calendar.getInstance(); for(int i = 0; i < numMonths; i++) { for(Date date : dates) { if(sameMonth(month, date) .. doSomething } month.add(Calendar.MONTH, -1); } Creating a new Calendar object for every date seems like a pretty hefty overhead when this comparison will happen thousands of times, soI kind of want to cheat a bit and use the deprecated method Date.getMonth() and Date.getYear() public static boolean sameMonth(Calendar month, Date date) { return month.get(Calendar.YEAR) == date.getYear() && month.get(Calendar.MONTH) == date.getMonth(); } I'm pretty close to just using this method, since it seems to be the fastest, but is there a faster way? And is this a foolish way, since the Date methods are deprecated? Note: This project will always run with Java 7

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• AttributeError in my Python program regarding classes

  - by Axel Finkel

  I'm doing an exercise out of the Python book that involves creating a class and a subclass. I am getting the following error when I try to run the program: AttributeError: 'Customer' object has no attribute 'name', when it tries to go through this bit of code: self.name.append(name) As this is my first time dealing with classes and objects in Python, I'm sure I am making some overt mistake somewhere, but I can't seem to figure it out. I've looked over the documentation for creating classes and writing member functions, and it looks correct, but it is obviously not. I want the Customer subclass to inherit the name, address, and telephone attributes from the Person superclass, but it doesn't seem to be doing so? Here is my code: class Person: def __init__(self): self.name = None self.address = None self.telephone = None def changeName(self, name): self.name.append(name) def changeAddress(self, address): self.address.append(address) def changeTelephone(self, telephone): self.telephone.append(telephone) class Customer(Person): def __init__(self): self.customerNumber = None self.onMailingList = False def changeCustomerNumber(self, customerNumber): self.customerNumber.append(customerNumber) def changeOnMailingList(): if onMailingList == False: onMailingList == True else: onMailingList == False def main(): customer1 = Customer() name = 'Bob Smith' address = '123 Somewhere Road' telephone = '111 222 3333' customerNumber = '12345' customer1.changeName(name) customer1.changeAddress(address) customer1.changeTelephone(telephone) customer1.changeCustomerNumber(customerNumber) print("Customer name: " + customer1.name) print("Customer address: " + customer1.address) print("Customer telephone number: " + customer1.telephone) print("Customer number: " + customer1.customerNumber) print("On mailing list: " + customer1.OnMailingList) customer1.changeOnMailingList() print("On mailing list: " + customer1.OnMailingList) main()

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• General web service ideas

  - by user2014175

  I have a question regarding different types of web services. I'll preface this by saying that I have built a number of apps (for both ios and android) for personal use that interact with the web via php and sql. I have taught myself these languages, and as such don't have the broader background knowledge that many of you do. My question is, in what other ways can you perform an interaction between a web service and a mobile device other than mobile - php - sql - etc. For example, If I built a very simple tracking app for my car, my current method would be to push GPS coordinates from my iphone to my database at a set interval, then I would write a simple bit of javascript that pulled those coordinates out of the database and superimposed them on a google map. Is there a different way to do this? Such as the server acting as a live middle man who simple pushed the coordinates directly to a target browser? Without the database in the middle? If so, are there advantages and disadvantages to these different methods to achieve different goals? I know its a broad question but I'm really intrigued and I'm finding it difficult to word a google search for it. Any info / reading material suggesting would be excellent. Thanks

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• VisualSVN How to roll back the revision number ?

  - by Ita

  The company I work in has suffered a major server failure. During this failure the SVN Repository was lost. But there is still hope ! We have an old backup of the repository which I've managed to successfully restore using VisualSVN. The problem I'm facing now is that I can't update / commit pre-failure checkedout folders. The reason for this problem is that for instance: a local folder has a revision number of 2361, while the repository itself holds a revision number of 2290, which is older. Is there a way to deal with this issue ? Can I some how change the revision numbers on either the local copy or the server copy? A few points: I'm using TortoiseSVN 1.6.6. I can checkout folders from the repo and the connection is active. I've picked one of my folders and used the Relocate option on it. This helped me see that there is something wrong with the revision number I've experimented a bit with the merge option but this lead me now where special. (I'm open for suggestions ) Thank you for your time, Ita

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• Change workarea size of Linux desktop

  - by nonoitall

  I'm trying to write a taskbar/panel for Linux (like fbpanel or pypanel) using GTK# and am a little hung up. I've created a Gtk.Window to act as the panel and positioned/resized it appropriately. I've also set its WindowTypeHint to Dock so that it remains on top of other windows. So far it 'looks' like a panel. However, if the panel is running and I maximize another window, that window fills the whole desktop - meaning the bottom portion of the window is covered up by my panel. I've gathered that I probably need to change the desktop's workarea. How can I go about doing this in C#? (Preferably using GTK#, but I don't mind using interop if it's necessary.) As a bit of a side point, I'm curious if anyone knows how I would go about 'informing' the window manager about where applications' taskbar buttons are. (For example, if the window manager wants to animate the minimize action so that the window shrinks down to its button on the taskbar, how do I let the window manager know where that button is on the taskbar?)

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• JAR files, don't they just bloat and slow Java down?

  - by Josamoto

  Okay, the question might seem dumb, but I'm asking it anyways. After struggling for hours to get a Spring + BlazeDS project up and running, I discovered that I was having problems with my project as a result of not including the right dependencies for Spring etc. There were .jars missing from my WEB-INF/lib folder, yes, silly me. After a while, I managed to get all the .jar files where they belong, and it comes at a whopping 12.5MB at that, and there's more than 30 of them! Which concerns me, but it probably and hopefully shouldn't be concerned. How does Java operate in terms of these JAR files, they do take up quite a bit of hard drive space, taking into account that it's compressed and compiled source code. So that can really quickly populate a lot of RAM and in an instant. My questions are: Does Java load an entire .jar file into memory when say for instance a class in that .jar is instantiated? What about stuff that's in the .jar that never gets used. Do .jars get cached somehow, for optimized application performance? When a single .jar is loaded, I understand that the thing sits in memory and is available across multiple HTTP requests (i.e. for the lifetime of the server instance running), unlike PHP where objects are created on the fly with each request, is this assumption correct? When using Spring, I'm thinking, I had to include all those fiddly .jars, wouldn't I just be better off just using native Java, with say at least and ORM solution like Hibernate? So far, Spring just took extra time configuring, extra hard drive space, extra memory, cpu consumption, so I'm concerned that the framework is going to cost too much application performance just to get for example, IoC implemented with my BlazeDS server. There still has to come ORM, a unit testing framework and bits and pieces here and there. It's just so easy to bloat up a project quickly and irresponsibly easily. Where do I draw the line?

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• Tools for managing code deployment/versioning for IIS / Windows enviroments

  - by RizwanK

  I've got a strong background in Linux and OSX, and just left a job where I was architecting systems based on those platforms. Now I've got a Windows Server running IIS that has a number of different websites that it hosts. Most of them are just a bunch of HTML, JS and Images, with some ASP for some customer tools. (Each website has a different set of customer tools, or they are the same tools, but with minor code changes between them.) I'm also adding a develop web server with the same code, but the 'bleeding edge' stuff. I need an effective way of managing changes and updates to the overall codebase (henceforth referring to both the images and the html and the asp, for all the sites). When a dev (or webmaster) checks in changes, I want it to show up automatically on the developer server, but should be manually pushed out to the live server. I'd be tempted to just make the websites SVN repositories, but I'd be concerned about the overhead of having the webdeveloper having to log into the server and trigger an SVN update via commandline/tortise (and heaven forbid, manage tags). Ideally I'd also manage IIS profile settings between the systems, but the major need is to be able to manage the process, and expose it to our ASP developer, and our webmaster, both of which are used to just FTPing up the files to the live site. So, any recommendations on tools (beyond some SVN hacking with BAT files + teaching the webmaster how to log into the server and do updates) or workflows that would help this out? I even considered an RPM type package (or some Windows equivalent, of course) to manage the live server, but that seems like a bit too much overhead. Thanks.

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• How to speed up a slow UPDATE query

  - by Mike Christensen

  I have the following UPDATE query: UPDATE Indexer.Pages SET LastError=NULL where LastError is not null; Right now, this query takes about 93 minutes to complete. I'd like to find ways to make this a bit faster. The Indexer.Pages table has around 506,000 rows, and about 490,000 of them contain a value for LastError, so I doubt I can take advantage of any indexes here. The table (when uncompressed) has about 46 gigs of data in it, however the majority of that data is in a text field called html. I believe simply loading and unloading that many pages is causing the slowdown. One idea would be to make a new table with just the Id and the html field, and keep Indexer.Pages as small as possible. However, testing this theory would be a decent amount of work since I actually don't have the hard disk space to create a copy of the table. I'd have to copy it over to another machine, drop the table, then copy the data back which would probably take all evening. Ideas? I'm using Postgres 9.0.0. UPDATE: Here's the schema: CREATE TABLE indexer.pages ( id uuid NOT NULL, url character varying(1024) NOT NULL, firstcrawled timestamp with time zone NOT NULL, lastcrawled timestamp with time zone NOT NULL, recipeid uuid, html text NOT NULL, lasterror character varying(1024), missingings smallint, CONSTRAINT pages_pkey PRIMARY KEY (id ), CONSTRAINT indexer_pages_uniqueurl UNIQUE (url ) ); I also have two indexes: CREATE INDEX idx_indexer_pages_missingings ON indexer.pages USING btree (missingings ) WHERE missingings > 0; and CREATE INDEX idx_indexer_pages_null ON indexer.pages USING btree (recipeid ) WHERE NULL::boolean; There are no triggers on this table, and there is one other table that has a FK constraint on Pages.PageId.

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• Recommendations for IPC between parent and child processes in .NET?

  - by Jeremy

  My .NET program needs to run an algorithm that makes heavy use of 3rd party libraries (32-bit), most of which are unmanaged code. I want to drive the CPU as hard as I can, so the code runs several threads in parallel to divide up the work. I find that running all these threads simultaneously results in temporary memory spikes, causing the process' virtual memory size to approach the 2 GB limit. This memory is released back pretty quickly, but occasionally if enough threads enter the wrong sections of code at once, the process crosses the "red line" and either the unmanaged code or the .NET code encounters an out of memory error. I can throttle back the number of threads but then my CPU usage is not as high as I would like. I am thinking of creating worker processes rather than worker threads to help avoid the out of memory errors, since doing so would give each thread of execution its own 2 GB of virtual address space (my box has lots of RAM). I am wondering what are the best/easiest methods to communicate the input and output between the processes in .NET? The file system is an obvious choice. I am used to shared memory, named pipes, and such from my UNIX background. Is there a Windows or .NET specific mechanism I should use?

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• synchronize threads - no UI

  - by UshaP

  I'm trying to write multithreading code and facing some synchronization questions. I know there are lots of posts here but I couldn't find anything that fits. I have a System.Timers.Timer that elapsed every 30 seconds it goes to the db and checks if there are any new jobs. If he finds one, he executes the job on the current thread (timer open new thread for every elapsed). While the job is running I need to notify the main thread (where the timer is) about the progress. Notes: I don't have UI so I can't do beginInvoke (or use background thread) as I usually do in winforms. I thought to implement ISynchronizeInvoke on my main class but that looks a little bit overkill (maybe I'm wrong here). I have an event in my job class and the main class register to it and I invoke the event whenever I need but I'm worrying it might cause blocking. Each job can take up to 20 minutes. I can have up to 20 jobs running concurrently. My question is: What is the right way to notify my main thread about any progress in my job thread? Thanks for any help.

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• What kind of data do I pass into a Django Model.save() method?

  - by poswald

  Lets say that we are getting POSTed a form like this in Django: rate=10 items= [23,12,31,52,83,34] The items are primary keys of an Item model. I have a bunch of business logic that will run and create more items based on this data, the results of some db lookups, and some business logic. I want to put that logic into a save signal or an overridden Model.save() method of another model (let's call it Inventory). The business logic will run when I create a new Inventory object using this form data. Inventory will look like this: class Inventory(models.Model): picked_items = models.ManyToManyField(Item, related_name="items_picked_set") calculated_items = models.ManyToManyField(Item, related_name="items_calculated_set") rate = models.DecimalField() ... other fields here ... New calculated_items will be created based on the passed in items which will be stored as picked_items. My question is this: is it better for the save() method on this model to accept: the request object (I don't really like this coupling) the form data as arguments or kwargs (a list of primary keys and the other form fields) a list of Items (The caller form or view will lookup the list of Items and create a list as well as pass in the other form fields) some other approach? I know this is a bit subjective, but I was wondering what the general idea is. I've looked through a lot of code but I'm having a hard time finding a pattern I like.

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• PC boot: dl register and drive number

  - by kikou

  I read somewhere in the internet that, before jumping to 0x7c00, the BIOS loads into %dl the "drive number" of the booted device. But what is this "drive number"? Each device attached to the computer is assigned a number by the BIOS? If so, how can I know which number is a given device assigned to? Reading GRUB's source code I found when %dl has bits 0x80 and 0x70 set, it overwrites the whole register with 0x80. Why is that? Here is the code: jmp 3f /* grub-setup may overwrite this jump */ testb $0x80, %dl jz 2f 3: /* Ignore %dl different from 0-0x0f and 0x80-0x8f. */ testb $0x70, %dl jz 1f 2: movb $0x80, %dl 1: By the way. Is there any detailed resource on the boot process of PC's in the web? Specially about what the BIOS does before giving the control to the bootloader and also the standard codes used to communicate with it (like that "drive numer"). I was hoping to write my own bootloader and everything I found is a bit too vague, not technical enough to the point of informing of the exact state of the computer when my bootloader starts to run.

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• Mysterious double execution of Click handler after change to Windows 2008 Server

  - by mjn

  After moving a Delphi 2009 application from a Windows 2003 / Citrix environment to a 64 bit Windows 2008 R2 environment (users now use RDP instead of Citrix), there are frequent runtime errors which are caused by a double exection of a menu item click handler. The first call of the event handler opens a modal form. Then the same event handler is triggered again and thus a runtime exception occurs since the visible form can not be made modal. The madExcept stack trace looks like this: main thread ($2dc): 004ffa88 +06c Ladelist.exe Forms TCustomForm.ShowModal 0052f4ff +0bb Ladelist.exe DB TDataSet.SetActive 008fc9a1 +089 Ladelist.exe u_ladeli 928 +16 TForm1.EditLoadingList 008fadec +070 Ladelist.exe u_ladeli 504 +5 TForm1.OpenLoadingListClick <----- 2 004d6e27 +0a7 Ladelist.exe Menus TMenuItem.Click 004d857f +0ef Ladelist.exe Menus DoClick 004d866b +087 Ladelist.exe Menus TMenu.IsShortCut 005001c1 +04d Ladelist.exe Forms TCustomForm.IsShortCut 004e8dc0 +068 Ladelist.exe Controls TWinControl.IsMenuKey 004e8f89 +011 Ladelist.exe Controls TWinControl.CNSysKeyDown 004e247e +2d2 Ladelist.exe Controls TControl.WndProc 004e6983 +513 Ladelist.exe Controls TWinControl.WndProc 004fb5e8 +594 Ladelist.exe Forms TCustomForm.WndProc 004e20a4 +024 Ladelist.exe Controls TControl.Perform 004856e0 +014 Ladelist.exe Classes StdWndProc 004e609c +02c Ladelist.exe Controls TWinControl.MainWndProc 004856e0 +014 Ladelist.exe Classes StdWndProc 775b00e3 +02b ntdll.dll KiUserCallbackDispatcher 008fc9a1 +089 Ladelist.exe u_ladeli 928 +16 TForm1.EditLoadingList 008fadec +070 Ladelist.exe u_ladeli 504 +5 TForm1.OpenLoadingListClick <----- 1 004d6e27 +0a7 Ladelist.exe Menus TMenuItem.Click 004d857f +0ef Ladelist.exe Menus DoClick 004d866b +087 Ladelist.exe Menus TMenu.IsShortCut 005001c1 +04d Ladelist.exe Forms TCustomForm.IsShortCut 004e8dc0 +068 Ladelist.exe Controls TWinControl.IsMenuKey 004e8e0d +01d Ladelist.exe Controls TWinControl.CNKeyDown 004e247e +2d2 Ladelist.exe Controls TControl.WndProc 004e6983 +513 Ladelist.exe Controls TWinControl.WndProc 004fb5e8 +594 Ladelist.exe Forms TCustomForm.WndProc 004e20a4 +024 Ladelist.exe Controls TControl.Perform 004e609c +02c Ladelist.exe Controls TWinControl.MainWndProc 004856e0 +014 Ladelist.exe Classes StdWndProc 775b00e3 +02b ntdll.dll KiUserCallbackDispatcher 753c3675 +010 kernel32.dll BaseThreadInitThunk

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• Which method of 'clearfix' is best?

  - by Pickledegg

  I have the age old problem of a div wrapping a 2 column layout. My sidebar is floated so my container div fails to wrap the content & sidebar. <div id="container"> <div id="content"> </div> <div id="sidebar"> </div> </div> There seem to be numerous methods of fixing the clear bug in FF: <br clear="all"/> overflow:auto overflow:hidden etc. But in my situation, the only one that seems to work correctly is the <br clear="all"/> solution, which is a little bit scruffy. overflow:auto gives me nasty scrollbars, and overflow:hidden must surely have side effects. Also, apparently IE7 is supposed to not suffer from this problem due to its incorrect behaviour, but again, in my situation its suffering the same as FF. Whats the most reliable/best practice method currently available to us?

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• When is it safe to use a broken hash function?

  - by The Rook

  It is trivial to use a secure hash function like SHA256 and continuing to use md5 is reckless behavior. However, there are some complexities to hash function vulnerabilities that I would like to better understand. Collisions have been generated for md4 and md5. According to NIST md5() is not a secure hash function. It only takes 2^39th operations to generate a collision and should never be used for passwords. However SHA1 is vulnerable to a similar collision attack in which a collision can be found in 2^69 operations, where as brute force is 2^80th. No one has generated a sha1 collision and NIST still lists sha1 as a secure message digest function. So when is it safe to use a broken hash function? Even though a function is broken it can still be "big enough". According to Schneier a hash function vulnerable to a collsion attack can still be used as an HMAC. I believe this is because the security of an HMAC is Dependant on its secret key and a collision cannot be found until this key is obtained. Once you have the key used in a HMAC its already broken, so its a moot point. What hash function vulnerabilities would undermine the security of an HMAC? Lets take this property a bit further. Does it then become safe to use a very weak message digest like md4 for passwords if a salt is perpended to the password? Keep in mind the md4 and md5 attacks are prefixing attacks, and if a salt is perpended then an attacker cannot control the prefix of the message. If the salt is truly a secret, and isn't known to the attacker, then does it matter if its a appended to the end of the password? Is it safe to assume that an attacker cannot generate a collision until the entire message has been obtained? Do you know of other cases where a broken hash function can be used in a security context without introducing a vulnerability? (Please post supporting evidence because it is awesome!)

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• JSON is not being recognised

  - by richzilla

  Hi All, Im having a bit of trouble getting my JSON to be recognised by my web page. I have validated JSON that im getting returned from server, so i know that is correct, however my javascript function is not doing anything with it. My succes function is as follows: success: function(data) { $('input[name=customer_name]').val(data.name); $('textarea[name=customer_address]').text(data.address); $('input[name=customer_email]').val(data.email); $('input[name=customer_tel]').val(data.tel); $('input[name=user_id]').val(item.id); } Yet the fields are not being repopulated with the data that is returned, if it helps, a sample of my JSON data: { "name": "Terry O'Toole", "address": "Terrys House\nTerry Street\nTerrysville\nTerrytown\nTT1 6TT", "email": "[email protected]", "tel": "05110000000" } Any help would be appreciated. [EDIT] Expanded ajax call: $.ajax({ url: "<?php echo site_url('user/users/ajax'); ?>", type: 'POST', data: {"userid": item.id}, success: function(data) { $('input[name=customer_name]').val(data.name); $('textarea[name=customer_address]').text(data.address); $('input[name=customer_email]').val(data.email); $('input[name=customer_tel]').val(data.tel); $('input[name=user_id]').val(item.id); } }) });

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• Multiple instances of the same Async task (Windows Phone)

  - by Bart Teunissen

  After googeling for ages, and reading some stuff about async task in books. I made a my first program with an async task in it. Only to find out, that i can only start one task. I want to run the task more then once. This is where i found out that that doesn't seem to work. to be a little bit clearer, here are some parts of my code: InitFunction(var); This is the Task itself public async Task InitFunction(string var) { _VarHandle = await _AdsClient.GetSymhandleByNameAsync(var); _Data = await _AdsClient.ReadAsync<T>(_VarHandle); _AdsClient.AddNotificationAsync<T>(_VarHandle, AdsTransmissionMode.OnChange, 1000, this); } This works like a charm when i execute the task only once.. But is there a possibility to run it multiple times. Something like this? InitFunction(var1); InitFunction(var2); InitFunction(var3); Because if i do this now (multiple tasks at once), the task it wants to start is still running, and it throws an exeption. if someone could help me with this, that would be awesome! ~ Bart

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• Robotlegs: Warning: Injector already has a rule for type

  - by MikeW

  I have a bunch of warning messages like this appear when using Robotlegs/Signals. Everytime this command class executes, which is every 2-3 seconds ..this message displays below If you have overwritten this mapping intentionally you can use "injector.unmap()" prior to your replacement mapping in order to avoid seeing this message. Warning: Injector already has a rule for type "mx.messaging.messages::IMessage", named "". The command functions fine otherwise but I think I'm doing something wrong anyhow. public class MessageReceivedCommand extends SignalCommand { [Inject] public var message:IMessage; ...etc.. do something with message.. } the application context doesnt map IMessage to this command, as I only see an option to mapSignalClass , besides the payload is received fine. Wonder if anyone knows how I might either fix or suppress this message. I've tried calling this as the warning suggests injector.unmap(IMessage, "") but I receive an error - no mapping found for ::IMessage named "". Thanks Edit: A bit more info about the error Here is the signal that I dispatch to the command public class GameMessageSignal extends Signal { public function GameMessageSignal() { super(IMessage); } } which is dispatched from a IPushDataService class gameMessage.dispatch(message.message); and the implementation is wired up in the app context via injector.mapClass(IPushDataService, PushDataService); along with the signal signalCommandMap.mapSignalClass(GameMessageSignal, MessageReceivedCommand); Edit #2: Probably good to point out also I inject an instance of GameMessageSignal into IPushDataService public class PushDataService extends BaseDataService implements IPushDataService { [Inject] public var gameMessage:GameMessageSignal; //then private function processMessage(message:MessageEvent):void { gameMessage.dispatch(message.message); } } Edit:3 The mappings i set up in the SignalContext: injector.mapSingleton(IPushDataService); injector.mapClass(IPushDataService, PushDataService);

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