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• Serializing C# objects to DB

  - by Robert Koritnik

  I'm using a DB table with various different entities. This means that I can't have an arbitrary number of fields in it to save all kinds of different entities. I want instead save just the most important fields (dates, reference IDs - kind of foreign key to various other tables, most important text fields etc.) and an additional text field where I'd like to store more complete object data. the most obvious solution would be to use XML strings and store those. The second most obvious choice would be JSON, that usually shorter and probably also faster to serialize/deserialize... And is probably also faster. But is it really? My objects also wouldn't need to be strictly serializable, because JsonSerializer is usually able to serialize anything. Even anonymous objects, that may as well be used here. What would be the most optimal solution to solve this problem?

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• Why is a fixed size buffers (arrays) must be unsafe?

  - by brickner

  Let's say I want to have a value type of 7 bytes (or 3 or 777). I can define it like that: public struct Buffer71 { public byte b0; public byte b1; public byte b2; public byte b3; public byte b4; public byte b5; public byte b6; } A simpler way to define it is using a fixed buffer public struct Buffer72 { public unsafe fixed byte bs[7]; } Of course the second definition is simpler. The problem lies with the unsafe keyword that must be provided for fixed buffers. I understand that this is implemented using pointers and hence unsafe. My question is why does it have to be unsafe? Why can't C# provide arbitrary constant length arrays and keep them as a value type instead of making it a C# reference type array or unsafe buffers?

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• Create user variable in Intellij File Template

  - by Matt Broekhuis

  I am trying to use Intellij's file templates (not live templates) to help mitigate how much boilerplate code I use when making Services, daos, and their interfaces. I am able to use all the system defined variables just fine, such as ${PACKAGE_NAME} What I want though, is to be able to use my own variable names, like ${MY_USER_INPUT} however, when i do this like above, I get an error The documentation says : It is also possible to specify arbitrary number of custom variables in format ${<VARIABLE_NAME>}. and then Intellij is supposed to prompt the user for the value. However, this just plain doesn't work for me. What am I missing?

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• Prevent SQL injection from form-generated SQL.

  - by Markos Fragkakis

  Hi all, I have a search table where user will be able to filter results with a filter of the type: Field [Name], Value [John], Remove Rule Field [Surname], Value [Blake], Remove Rule Field [Has Children], Value [Yes], Remove Rule Add Rule So the user will be able to set an arbitrary set of filters, which will result essentially in a completely dynamic WHERE clause. In the future I will also have to implement more complicated logical expressions, like Where (name=John OR name=Nick) AND (surname=Blake OR surname=Bourne), Of all 10 fields the user may or may not filter by, I don't know how many and which filters the user will set. So, I cannot use a prepared statement (which assumes that at least we know the fields in the WHERE clause). This is why prepared statements are unfortunately out of the question, I have to do it with plain old, generated SQL. What measures can I take to protect the application from SQL Injection (REGEX-wise or any other way)?

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• Flexible argument list in LibreOffice Calc Macro

  - by Patru

  I want to write a function that geometrically links performance data which is usually provided as percentages, so the function will basically return (1+a)*(1+b)*(1+c)* … *(1+x)-1 This should be done using LibreOffice-calc and it should behave similarly to the regular sum function. As you may throw any number of arguments at sum I would like to be able to do the same with my alternative geoSum function but I am unable to find suitable documentation on handling a variable number of arguments with variable types (i.e. an arbitrary mix of numbers, cells and ranges). How would I have to specify the arguments to my LibreOffice-Basic function and how would I have to interpret it?

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• Python encoding for pipe.communicate

  - by Brian M. Hunt

  I'm calling pipe.communicate from Python's subprocess module from Python 2.6. I get the following error from this code: from subprocess import Popen pipe = Popen(cwd) pipe.communicate( data ) For an arbitrary cwd, and where data that contains unicode (specifically 0xE9): Exec. exception: 'ascii' codec can't encode character u'\xe9' in position 507: ordinal not in range(128) Traceback (most recent call last): ... stdout, stderr = pipe.communicate( data ) File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/subprocess.py", line 671, in communicate return self._communicate(input) File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/subprocess.py", line 1177, in _communicate bytes_written = os.write(self.stdin.fileno(), chunk) This is happening, I presume, because pipe.communicate() is expecting ASCII encoded string, but data is unicode. Is this the problem I'm encountering, and i sthere a way to pass unicode to pipe.communicate()? Thank you for reading! Brian

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• How do you implement Software Transactional Memory?

  - by Joseph Garvin

  In terms of actual low level atomic instructions and memory fences (I assume they're used), how do you implement STM? The part that's mysterious to me is that given some arbitrary chunk of code, you need a way to go back afterward and determine if the values used in each step were valid. How do you do that, and how do you do it efficiently? This would also seem to suggest that just like any other 'locking' solution you want to keep your critical sections as small as possible (to decrease the probability of a conflict), am I right? Also, can STM simply detect "another thread entered this area while the computation was executing, therefore the computation is invalid" or can it actually detect whether clobbered values were used (and thus by luck sometimes two threads may execute the same critical section simultaneously without need for rollback)?

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• Why do C# automatic properties not support default values like VB 2010?

  - by Rob van Groenewoud

  Looking at the new VB 2010 features, I stumbled upon support for Auto-Implemented Properties. Since I'm working with C#, this seemed quite familiar, but I noticed that VB did add a feature I would love to have in C#: setting a arbitrary default value for the auto-implemented property: I really like the clean usage of auto-properties in C#. This would save us the effort of introducing a backing field and hooking it up to the property everytime we simply need a default value, thereby cluttering up the code unnecessarily. I was wondering why this wasn't introduced in C# as well? What could be the rationale for not doing this? Is a syntax discussion going on, or are there technical limitations to implementing this?

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• Firewall will not play ball

  - by Jason94

  I'm running SQL Server 2008 Express on a windows 2012... or at least I'm trying to :) My problem is that I have opened the ports I thought I needed but still I cant manage to connect to the database from Visual Studio. As proof I have a screenshot of my firewall settings: Everything works fine if I turn the firewall off, but who wants that while connected to the internet? So I wonder what the heck is wrong? Is that some arbitrary ports that gets blocked? Is that a feature on the server (maybe its the same for 2008?) Large image: http://bildr.no/view/1280743

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• Write wave files to memory in Java

  - by Cliff

  I'm trying to figure out why my servlet code creates wave files with improper headers. I use: AudioSystem.write( new AudioInputStream( new ByteArrayInputStream(memoryBytes), new AudioFormat(22000, 16, 1, true,false), memoryBytes.length ), AudioFileFormat.Type.WAVE, servletOutputStream ); taking a byte array from memory containing raw PCM samples and a servlet output stream that gets returned to the client. In the result I get a normal wave file but with zeros in the chunk size fields. Is the API broken? I would think that the size could be filled in using the size passed in the audio input stream. But now, after typing this out I'm thinking its not making this info available to the outer write() method on AudioSystem. It seems like the AudioSystem.write call needs a size parameter unless it is able to pull the size from the stream... which wouldn't work with an arbitrary sized stream. Does anyone know how to make this example work?

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• How do I compute the approximate entropy of a bit string?

  - by dreeves

  Is there a standard way to do this? Googling -- "approximate entropy" bits -- uncovers multiple academic papers but I'd like to just find a chunk of pseudocode defining the approximate entropy for a given bit string of arbitrary length. (In case this is easier said than done and it depends on the application, my application involves 16,320 bits of encrypted data (cyphertext). But encrypted as a puzzle and not meant to be impossible to crack. I thought I'd first check the entropy but couldn't easily find a good definition of such. So it seemed like a question that ought to be on StackOverflow! Ideas for where to begin with de-cyphering 16k random-seeming bits are also welcome...) See also this related question: http://stackoverflow.com/questions/510412/what-is-the-computer-science-definition-of-entropy

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• What are the ways to do synchronized streaming video and text?

  - by Marc

  I would like to have two streams. One being traditional streaming video and another being text. I will also build an interface that allows the user to create the text portion while watching the video. The context of these videos are usually that of an individual being filmed doing a presentation and later the next day for example, a coach will make text annotations (structured data is a plus) with the result being the text stream. It seems this is possible with Silverlight (see the article in the latest MSDN). However, what other methods are there if any? If there any, please give the reasons for why you are recommending them. Thanks. Also, I would prefer something that inst a software as a service hosted solution, but, dont let that keep you from giving an answer. Also keep in mind, the user shouldn't have to do any re-encoding of the video source, the text stream should be separate with someway to synchronize a coach's comments to an arbitrary time stamp in the video.

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• Very long strings as primary keys in a database for caching

  - by Bill Zimmerman

  Hi, I am working on a web app that allows users to create dynamic PDF files based on what they enter into a form (it is not very structured data). The idea is that User 1 enters several words (arbitrary # of words, practically capped of course), for example: A B C D E There is no such string in the database, so I was thinking: Store this string as a primary key in a MySQL database (it could be maybe around 50-100k of text, but usually probably less than 200 words) Generate the PDF file, and create a link to it in the database When the next user requests A B C D E, then I can just serve the file instead of recreating it each time. (simple cache) The PDF is cpu intensive to generate, so I am trying to cache as much as I can... My questions are: Does anyone have any alternative ideas to my approach What will the database performance be like? Is there a better way to design the schema than using the input string as the primary key?

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• sound volume increase beyond 100% whenever possible on linux

  - by fakedrake

  Some audio output from files or streams is too low. It is obvious that hardware is able to play the same sounds but louder but because of the data it just plays it at some low level even at 100% volume. Vlc can generally increase the volume of a file up to 200%. Is there a way to do the same thing VLC does system-wide and if possible for an arbitrary v percentage value. If there is no application that does this, where should i look into for libs to do it myself or what code should i modify(eg code in the alsamixer) thank you

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• Does any one know of a packet generator?

  - by Benoit

  We have a networked device, and we would like to perform some tests on how it handles malformed packets. Is there a product out there that can generate arbitrary packets and packet sequences? I would like to be able to specify a set of TCP/IP payloads and it would open a connection and send the data. Obviouly, the TCP/IP checksum should be calculated correctly, etc... Kind of like a wireshark in reverse. Note that I am not interested in network loading and blasting millions of packet.

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• Using glRotate and glTranslate with collision detection.

  - by Cetra

  Hey guys, Say I use glRotate to translate the current view based on some arbitrary user input (i.e, if key left is pressed then rtri+=2.5f) glRotatef(rtri,0.0f,1.0f,0.0f); Then I draw the triangle in the rotated position: glBegin(GL_TRIANGLES); // Drawing Using Triangles glVertex3f( 0.0f, 1.0f, 0.0f); // Top glVertex3f(-1.0f,-1.0f, 0.0f); // Bottom Left glVertex3f( 1.0f,-1.0f, 0.0f); // Bottom Right glEnd(); // Finished Drawing The Triangle How do I get the resulting translated vertexes for use in collision detection? Or will I have to manually apply the transform myself and thus doubling up the work? The reason I ask is that I wouldn't mind implementing display lists.

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• What CPAN module can summarize error logs?

  - by mithaldu

  I'm maintaining some website code that will soon dump all its errors and warnings into a log file. In order to make this a bit more pro-active i plan to parse this log file daily, summarize the warnings and errors (i.e. count the occurrence of each specific one and group by either warning/error) and then email this to the devs on the project. This would likely admittedly be rather trivial with a hash and some further fiddling, I wondered if there is a suitable module on CPAN that i could use to do this task. It would either be one that summarizes specifically perl error/warnings logs or one that summarizes arbitrary text files. Any suggestions?

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• What is the maximum distance from an anchor point to a bezier curve?

  - by drawnonward

  Given a cubic bezier curve P0,P1,P2,P3 with the following properties: • Both P1 and P2 are on the same side of the line formed by P0 and P3. • P2 can be projected onto the line segment formed by P0 and P3 but P1 cannot. What is the T value for the point on the curve farthest from P3? Here is an image with an example curve. The curve bulges on the left, so there is a point on the curve farther from P3 than P0. I found this reference for finding the minimum distance from an arbitrary point to a curve. Is trial and error the only way to solve for maximum distance as well? Does it make any difference that the point is an anchor on the curve? Thanks

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• Join one row to multiple rows in another table

  - by Ghostrider

  I have a table to entities (lets call them people) and properties (one person can have an arbitrary number of properties). Ex: People Name Age -------- Jane 27 Joe 36 Jim 16 Properties Name Property ----------------- Jane Smart Jane Funny Jane Good-looking Joe Smart Joe Workaholic Jim Funny Jim Young I would like to write an efficient select that would select people based on age and return all or some of their properties. Ex: People older than 26 Name Properties Jane Smart, Funny, Good-looking Joe Smart, Workaholic It's also acceptable to return one of the properties and total property count. The query should be efficient: there are millions of rows in people table, hundreds of thousands of rows in properties table (so most people have no properties). There are hundreds of rows selected at a time. Is there any way to do it?

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• Storing UTF-8 XML using Word's CustomXMLPart or any other supported way

  - by wpfwannabe

  I am writing a Word add-in which is supposed to store some own XML data per document using Word object model and its CustomXMLPart. The problem I am now facing is the lack of IStream-like functionality for reading/writing XML to/from a CustomXMLPart. It only provides BSTR interface and I am puzzled how to handle UTF-8 XMLs with BSTRs. To my understanding an UTF-8 XML file should really never have to undergo this sort of Unicode conversion. I am not sure what to expect as a result here. Is there another way of using Word automation interfaces to store arbitrary custom information inside a DOCX file?

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• Fancybox iframe says that my YouTube href is undefined

  - by user369732

  Here is my HTML: <a class="video iframe" href="http://www.youtube.com/watch?v=Psk2Pq03rv0">Arbitrary text</a> Here is the Fancybox javascript: $("a.video").fancybox({ 'padding' : 0, 'autoScale' : false, 'title' : this.title, 'overlayOpacity' : '.6', 'overlayColor' : '#333', 'transitionIn' : 'none', 'transitionOut' : 'none', 'centerOnScroll' : false, 'showCloseButton' : true, 'hideOnOverlayClick': false, 'href' : this.href.replace(new RegExp("watch\\?v=", "i"), "v/"), 'type' : 'swf', 'swf' : { 'wmode': 'transparent', 'allowfullscreen': 'true' } }); Firebug Console says: this.href is undefined 'href' : this.href.replace(new RegExp("watch\\?v=", "i"), 'v/'), As a result, clicking this link takes the user to YouTube and does not trigger Fancybox. Any advice?

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• Erlang Mnesia Equivalent of SQL Select FROM WHERE Field IN (value1, value2, value3, ...)

  - by ErJab

  I have an mnesia table with fields say f1, f2, f3. Now if I were to select all the rows with the field value as V1, I would use mnesia:select and match specifications or a simple mnesia:match_object. Now I need to select all the rows which have V1, V2, V3 ... or Vn (a list of arbitrary length) as the value for field f1. In SQL I would do something like SELECT * FROM tablename WHERE f3 IN (V1, V2, V3, ... , Vn) How do I do this in mnesia?

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• Flatten (an irregular) list of lists in Python

  - by telliott99

  Yes, I know this subject has been covered before (here, here, here, here), but AFAIK, all solutions save one choke on a list like this: L = [[[1, 2, 3], [4, 5]], 6] where the desired output is [1, 2, 3, 4, 5, 6] or perhaps even better, an iterator. The only solution I saw that works for an arbitrary nesting is from @Alabaster Codify here: def flatten(x): result = [] for el in x: if hasattr(el, "__iter__") and not isinstance(el, basestring): result.extend(flatten(el)) else: result.append(el) return result flatten(L) So to my question: is this the best model? Did I overlook something? Any problems?

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• How to efficiently SELECT rows from database table based on selected set of values

  - by Chau Chee Yang

  I have a transaction table of 1 million rows. The table has a field name "Code" to keep customer's ID. There are about 10,000 different customer code. I have an GUI interface allow user to render a report from transaction table. User may select arbitrary number of customers for rendering. I use IN operator first and it works for few customers: SELECT * FROM TRANS_TABLE WHERE CODE IN ('...', '...', '...') I quickly run into problem if I select few thousand customers. There is limitation using IN operator. An alternate way is create a temporary table with only one field of CODE, and inject selected customer codes into the temporary table using INSERT statement. I may then using SELECT A.* FROM TRANS_TABLE A INNER JOIN TEMP B ON (A.CODE=B.CODE) This works nice for huge selection. However, there is performance overhead for temporary table creation, INSERT injection and dropping of temporary table. Do you aware of better solution to handle this situation?

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• JavaScript Metaprogramming: Reduce boilerplate of adding functions to a function queue

  - by thurn

  I'm working with animation in JavaScript, and I have a bunch of functions you can call to add things to the animation queue. Basically, all of these functions look like this: function foo(arg1, arg2) { _eventQueue.push(function() { // actual logic } } I'm wondering now if it would be possible to cut down on this boilerplate a little bit, though, so I don't need that extra "_eventQueue" line in the function body dozens of times. Would it be possible, for example, to make a helper function which takes an arbitrary function as an argument and returns a new function which is augmented to be automatically added to the event queue? The only problem is that I need to find a way to maintain access to the function's original arguments in this process, which is... complicated.

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