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  • Efficient JSON encoding for data that may be binary, but is often text

    - by Evgeny
    I need to send a JSON packet across the wire with the contents of an arbitrary file. This may be a binary file (like a ZIP file), but most often it will be plain ASCII text. I'm currently using base64 encoding, which handles all files, but it increases the size of the data significantly - even if the file is ASCII to begin with. Is there a more efficient way I can encode the data, other than manually checking for any non-ASCII characters and then deciding whether or not to base64-encode it? I'm currently writing this in Python, but will probably need to do the same in Java, C# and C++, so an easily portable solution would be preferable.

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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 to manually query LDAP through Acegi's beans?

    - by Veggen Skrikk
    I have an application using Acegi (earlier version of Spring Security) and LDAP for logins. Now, a specific scenario requires me to discover user's LDAP groups at arbitrary time (not at login time). Is it possible to use already set up Acegi to handle this situation? I'm thinking of using the configured LdapAuthProvider (or LdapAuthPopulator or whatever's appropriate) to get all the groups associated with a given username. Is this possible? If yes, please, please, give some hints how it should be done...

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  • Interactive pyDev console at breakpoint

    - by fest
    I'm using Aptana Studio with Pydev 1.5.3 to debug my Django applications. I use PyDev's remote debugger and some code in manage.py and for most of the time this setup is working successfully- I can set breakpoints, inspect variables and step/continue through my code. However, I'd like to execute arbitrary code at the breakpoint- the thing I really miss after switching from pdb to Eclipse debugging. There is an interactive console available in debug perspective but it is inactive for me. So my question- is it possible to set up an interactive console in PyDev with remote debugger which could "inject" code at breakpoint?

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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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  • what is order notation f(n)=O(g(n))?

    - by Lopa
    2 questions: question 1: under what circumstances would this[O(f(n))=O(k.f(n))] be the most appropriate form of time-complexity analysis? question 2: working from mathematical definition of O notation, show that O(f(n))=O(k.f(n)), for positive constant k.? My view: For the first one I think it is average case and worst case form of time-complexity. am i right? and what else do i write in that? for the second one I think we need to define the function mathematically, so is the answer something like because the multiplication by a constant just corresponds to a readjustment of value of the arbitrary constant 'k' in definition of O.

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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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  • 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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  • 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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  • 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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  • 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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  • What language is to binary, as Perl is to text?

    - by ehdr
    I am looking for a scripting (or higher level programming) language (or e.g. modules for Python or similar languages) for effortlessly analyzing and manipulating binary data in files (e.g. core dumps), much like Perl allows manipulating text files very smoothly. Things I want to do include presenting arbitrary chunks of the data in various forms (binary, decimal, hex), convert data from one endianess to another, etc. That is, things you normally would use C or assembly for, but I'm looking for a language which allows for writing tiny pieces of code for highly specific, one-time purposes very quickly. Any suggestions?

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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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  • 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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  • 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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  • Why does LINQ-to-SQL Paging fail inside a function?

    - by ssg
    Here I have an arbitrary IEnumerable<T>. And I'd like to page it using a generic helper function instead of writing Skip/Take pairs every time. Here is my function: IEnumerable<T> GetPagedResults<T>(IEnumerable<T> query, int pageIndex, int pageSize) { return query.Skip((pageIndex - 1) * pageSize).Take(pageSize); } And my code is: result = GetPagedResults(query, 1, 10).ToList(); This produces a SELECT statement without TOP 10 keyword. But this code below produces the SELECT with it: result = query.Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList(); What am I doing wrong in the function?

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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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  • 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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  • serving files using django - is this a security vulnerability

    - by Tom Tom
    I'm using the following code to serve uploaded files from a login secured view in a django app. Do you think that there is a security vulnerability in this code? I'm a bit concerned about that the user could place arbitrary strings in the url after the upload/ and this is directly mapped to the local filesystem. Actually I don't think that it is a vulnerability issue, since the access to the filesystem is restricted to the files in the folder defined with the UPLOAD_LOCATION setting. UPLOAD_LOCATION = is set to a not publicly available folder on the webserver url(r'^upload/(?P<file_url>[/,.,\s,_,\-,\w]+)', 'aeon_infrastructure.views.serve_upload_files', name='project_detail'), @login_required def serve_upload_files(request, file_url): import os.path import mimetypes mimetypes.init() try: file_path = settings.UPLOAD_LOCATION + '/' + file_url fsock = open(file_path,"r") file_name = os.path.basename(file_path) file_size = os.path.getsize(file_path) print "file size is: " + str(file_size) mime_type_guess = mimetypes.guess_type(file_name) if mime_type_guess is not None: response = HttpResponse(fsock, mimetype=mime_type_guess[0]) response['Content-Disposition'] = 'attachment; filename=' + file_name #response.write(file) except IOError: response = HttpResponseNotFound() return response

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  • Problem with a SQL statement

    - by benwad
    I'm trying to enter values into a database table using a form and a PHP function. The PHP seems to be fine as the SQL statement it creates looks okay, but the database always throws up an error. This is the SQL statement that my code has generated (with arbitrary values): INSERT INTO Iteminfo ('itemName', 'itemSeller', 'itemCategory', 'itemDescription', 'itemPrice', 'itemPostage', 'itemBegin', 'itemEnd', 'buynow', 'itemPicture') values ('gorillaz album', 'ben', 'music', 'new one ', '5.00', '1.00', '2010-03-15 14:59:51', '2010-03-16 14:59:51', '0', 'http://www.thefader.com/wp-content/uploads/2010/01/gorillaz-plastic-beach.jpg') This throws up an error both when I use the PHP function to evaluate the query and also when I use phpMyAdmin to enter the query manually. However, I can't see anything wrong with it. Can anyone shed some light on this? All of the fields are VARCHAR values, except for itemPrice and itemPostage (which are stored as DECIMAL(4,2)) and the itemBegin and itemEnd, which are stored as DATETIMEs.

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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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  • 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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  • 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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  • 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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