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  • Need to calculate rotation-vector from Sensor.TYPE_ORIENTATION data

    - by Sponge
    I need to calculate a rotation vector out of the data i get from Sensor.TYPE_ORIENTATION. The sensor data is defined like this: the values have to be recalculated to become a correct 3d position: values[0]: Azimuth, angle between the magnetic north direction and the Y axis, around the Z axis (0 to 359). 0=North, 90=East, 180=South, 270=West values[1]: Pitch, rotation around X axis (-180 to 180), with positive values when the z-axis moves toward the y-axis. values[2]: Roll, rotation around Y axis (-90 to 90), with positive values when the x-axis moves away from the z-axis I need all three values like the Z axis value (from 0 to 360 degree). I tried a lot but cant figure out how to do this :/ i also tried to use Sensor.TYPE_ACCELEROMETER and Sensor.TYPE_MAGNETIC_FIELD to calculate this 3d vector on my own. here is the code: final float[] inR = new float[16]; // load inR matrix from current sensor data: SensorManager.getRotationMatrix(inR, null, gravityValues, geomagneticValues); float[] orientation = new float[3]; SensorManager.getOrientation(inR, orientation); mapMagAndAcclDataToVector(orientation); //here i do some *360 stuff orientetionChanged(orientation); //then the correct values are passed (in theorie) But this didn't work and i think it is much to complicated. So i bet there is a simple solution how to recalc the values of ensor.TYPE_ORIENTATION to make them a 3d rotation vector, but i just dont know how to do it. If you know the answer please tell me.

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  • Database Error Handling: What if You have to Call Outside service and the Transaction Fails?

    - by Ngu Soon Hui
    We all know that we can always wrap our database call in transaction ( with or without a proper ORM), in a form like this: $con = Propel::getConnection(EventPeer::DATABASE_NAME); try { $con->begin(); // do your update, save, delete or whatever here. $con->commit(); } catch (PropelException $e) { $con->rollback(); throw $e; } This way would guarantee that if the transaction fails, the database is restored to the correct status. But the problem is that let's say when I do a transaction, in addition to that transaction, I need to update another database ( an example would be when I update an entry in a column in databaseA, another entry in a column in databaseB must be updated). How to handle this case? Let's say, this is my code, I have three databases that need to be updated ( dbA, dbB, dbc): $con = Propel::getConnection("dbA"); try { $con->begin(); // update to dbA // update to dbB //update to dbc $con->commit(); } catch (PropelException $e) { $con->rollback(); throw $e; } If dbc fails, I can rollback the dbA but I can't rollback dbb. I think this problem should be database independent. And since I am using ORM, this should be ORM independent as well. Update: Some of the database transactions are wrapped in ORM, some are using naked PDO, oledb ( or whatever bare minimum language provided database calls). So my solution has to take care this. Any idea?

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  • Creating Mobile Cross-Platform Scripting Solution

    - by Aplomb
    I am having the dream to design a Mobile cross-platform scripting solution to achieve Developer only need to code once by scripting language(it's possible be Javascript or others need further investigation), then the solution will be able to generate the installation files for multiple mobile platforms like J2me, Android, Symbian, BlackBerry, Palm, Windows Mobile/Phone, iPhone, etc. Using the scripting language, developer can code with unified platform API. And other extension frameworks under scripting language, like, 1. 2D UI framework Most probably using for Mobile Applications, the UI style will compete with native UI framework and no longer every application in particular platform looks similar. 2. 3D UI framework Provide the platforms who has 3D capability can represent their Mobile Application with more fashion 3D style which will be much more abstractive. 3. Variable game engine Developers can can use it for easily and high-quality build games. 4. etc This Mobile solution is providing three points, 1. Cross-Platform 2. Scripting 3. Middleware So guys, what do you think about this idea, is it good for Developers? is it profitable? where is the better direction for this idea?

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  • Should you declare methods using overloads or optional parameters in C# 4.0?

    - by Greg Beech
    I was watching Anders' talk about C# 4.0 and sneak preview of C# 5.0, and it got me thinking about when optional parameters are available in C# what is going to be the recommended way to declare methods that do not need all parameters specified? For example something like the FileStream class has about fifteen different constructors which can be divided into logical 'families' e.g. the ones below from a string, the ones from an IntPtr and the ones from a SafeFileHandle. FileStream(string,FileMode); FileStream(string,FileMode,FileAccess); FileStream(string,FileMode,FileAccess,FileShare); FileStream(string,FileMode,FileAccess,FileShare,int); FileStream(string,FileMode,FileAccess,FileShare,int,bool); It seems to me that this type of pattern could be simplified by having three constructors instead, and using optional parameters for the ones that can be defaulted, which would make the different families of constructors more distinct [note: I know this change will not be made in the BCL, I'm talking hypothetically for this type of situation]. What do you think? From C# 4.0 will it make more sense to make closely related groups of constructors and methods a single method with optional parameters, or is there a good reason to stick with the traditional many-overload mechanism?

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  • Start-job to call script from main

    - by Naveen
    I have three script , from main - 1-script , I am calling other two scripts. so that I can execute both scripts parallely because it's taking too much time in sequential order. Only variables are different in the script. How can I merge script 2 & 3 in a single script so that I can call from the main script and it will run as parallel. 1 CompareCtrlM... Completed False localhost ######################... 3 CompareCtrlM... Completed True localhost ######################... Main -1 Script Start-Job -Name "LoopComparectrlMasterModel" -filepath D:\tmp\naveen\Script\CompareCtrlMasterCtrlModel.ps1 Start-Job -Name "LoopCompareProdMasterModel" -filepath D:\idv\CA\rcm_data\tmp\work\CompareCtrlMasterProdModel.ps1 Wait-Job -Name "LoopComparectrlMasterModel" Receive-Job "LoopComparectrlMasterModel" Wait-Job -Name "LoopCompareProdMasterModel" Receive-Job "LoopCompareProdMasterModel" =============================================== Script 2- for ($i = 1 ; $i -lt 3; $i++){ $jobName = 'CompareCtrlMasterProdModelESS$i' echolog $THISSCRIPT $RCM_UPDATE_LOG_FILE $LLINFO ("Starting Ctrl Master-Prod Model comparison #" + $i + ", create SBT") $rc = CreateSbtFile $sbtCompareCtrlMasterProdModel[$i-1] $cfgProdModel $cfgCtrlMaster "" "" $SBT_MODE_COMPARE_CFGS_FULL $workDir Start-Job -Name "$jobName" -filepath $ExecuteSbtWithRcmClientTool -ArgumentList $sbtCompareCtrlMasterProdModel[$i-1],"",$true,$false | Out-Null Wait-Job -Name "$jobName" $results = Receive-Job -Name $jobName } ========================================================================== Script 3- for ($i = 1 ; $i -lt 3; $i++){ $jobName = 'CompareCtrlMasterCtrlModelESS$i' echolog $THISSCRIPT $RCM_UPDATE_LOG_FILE $LLINFO ("Starting Ctrl Master-Ctrl Model comparison #" + $i + ", create SBT") $rc = CreateSbtFile $sbtCompareCtrlMasterCtrlModel[$i-1] $cfgCtrlModel $cfgCtrlMaster "" "" $SBT_MODE_COMPARE_CFGS_FULL $workDir Start-Job -Name "$jobName" -filepath $ExecuteSbtWithRcmClientTool -ArgumentList $sbtCompareCtrlMasterCtrlModel[$i-1],"",$true,$false | Out-Null Wait-Job -Name "$jobName" $results = Receive-Job -Name $jobName } write-output $results Thanks a lot for help Regards Naven

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  • Binary files printing and desired precision

    - by yCalleecharan
    Hi, I'm printing a variable say z1 which is a 1-D array containing floating point numbers to a text file so that I can import into Matlab or GNUPlot for plotting. I've heard that binary files (.dat) are smaller than .txt files. The definition that I currently use for printing to a .txt file is: void create_out_file(const char *file_name, const long double *z1, size_t z_size){ FILE *out; size_t i; if((out = _fsopen(file_name, "w+", _SH_DENYWR)) == NULL){ fprintf(stderr, "***> Open error on output file %s", file_name); exit(-1); } for(i = 0; i < z_size; i++) fprintf(out, "%.16Le\n", z1[i]); fclose(out); } I have three questions: Are binary files really more compact than text files?; If yes, I would like to know how to modify the above code so that I can print the values of the array z1 to a binary file. I've read that fprintf has to be replaced with fwrite. My output file say dodo.dat should contain the values of array z1 with one floating number per line. I have %.16Le up in my code but I think that %.15Le is right as I have 15 precision digits with long double. I have put a dot (.) in the width position as I believe that this allows expansion to an arbitrary field to hold the desired number. Am I right? As an example with %.16Le, I can have an output like 1.0047914240730432e-002 which gives me 16 precision digits and the width of the field has the right width to display the number correctly. Is placing a dot (.) in the width position instead of a width value a good practice? Thanks a lot...

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  • Changing character encoding in MySQL, PHP scripts, HTML

    - by Sandman
    So, I have built on this system for quite some time, and it is currently outputting Latin1 (ISO-8859-1) to the web browser, and this is the components: MySQL - all data is stored with the Latin1 character set PHP - All PHP text files are stored on disk with Latin1 encoding HTML - The output has the http-equiv="content-type" content="text/html; charset=iso-8859-1" meta tag So, I'm trying to understand how the encoding of the different parts come into play in my workflow. If I open a PHP script and change its encoding within the text editor to UTF-8 and save it back to disk and reload the web browser, the text is all messed up - unless the text comes from the DB. If I change the encoding of the DB to UTF-8 and keep the PHP files in latin1 I have to use utf8_decode() for the data to display correctly. And if I change the HTML code the browser will read it incorrectly. So yeah, I realise that if I want to "upgrade" to UTF8, I have to update all three parts of this setup for it to work correctly, but since it's a huge system with some 180k lines of PHP code and millions of posts in a lot of databases/tables, I don't want to start something like this without understanding everything correctly. What haven't I thought about? What could mess this up beyond fixing? What are the procedures for changing the encoding of an entire MySQL installation and what's the easiest way to change the encoding of hundreds or thousands of PHP files on disk? The META tag is luckily added dynamically, so I'll change that in one place only :) Let me hear about your experiences with this.

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  • javascript: waiting for an iframe page to load before writing to it (but not from the page that's tr

    - by Bill Dawes
    Apologies if this has been answered elsewhere, but I haven't been able to find it referenced. (Probably because nobody else would want to do such a daft thing, I admit). So, I have a page with three iframes in it. An event on one triggers a javascript function which loads new pages into the other two iframes; ['topright'] and ['bottomright']. However, javascript in the page that is being loaded into iframe 'topright' then needs to send information to elements in the 'bottomright' iframe. window.frames['bottomright'].document.subform.ID_client = client; etc But this will only work if the page has fully loaded into the bottomright frame. So what would be the most efficient way for that code in the 'topright' iframe to check and ensure that that form element in the bottomright frame is actually available to write to, before it does write to it? Bearing in mind that the page load has NOT been triggered from the topright frame, so I can't simply use an onLoad function. (I know this probably sounds like a hideously tortuous route for getting data from one page to another, but that's another story. The client is always right, etc...:-))

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  • Flex 4 / Flash 4 Add to Current State

    - by user163757
    I am having a little difficulty working with states in Flex (or Flash) 4. Lets say that my application has three states; the default (base) state, state 1, and state 2. State 1 should always be based on the base state, that's easy enough to accomplish. However, I would like state 2 to be based on the current state (either base or state 1). I can't for the life of me figure it out. I tried setting the basedOn property of state 1 to "this.currentState", but that just crashes my browser. <s:states> <s:State name="default"/> <s:State name="state1"/> <s:State name="state2" basedOn="{this.currentState}"/> </s:states> <s:TitleWindow id="configWindow" includeIn="state1" width="250" height="100%" close="configWindow_closeHandler(event)"/> <s:Panel id="settings" includeIn="state2" width="200" height="200"/>

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  • How do I show TextView's in LinearLayout that layed on other Layout?

    - by gelassen
    Good day. I have three layouts: first is the root, second and third lie in first. I try add TextView object in third layout and objects had been added in third layout (I saw it in debage mode) but this objects didn't showed on screen. May be someone know where is the problem? <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical"> <LinearLayout android:layout_width="fill_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <Button android:id="@+id/addJokeButton" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="@string/app_name" /> <EditText android:id="@+id/newJokeEditText" android:layout_width="fill_parent" android:layout_height="wrap_content" /> </LinearLayout> <LinearLayout android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical"> </LinearLayout> </LinearLayout> protected void initLayout() { setContentView(R.layout.advanced); LinearLayout linearLayout = (LinearLayout) getLayoutInflater().inflate( R.layout.advanced, null); m_vwJokeEditText = (EditText) findViewById(R.id.newJokeEditText); m_vwJokeButton = (Button) findViewById(R.id.addJokeButton); m_vwJokeLayout = (LinearLayout) linearLayout.getChildAt(1); } protected void addJoke(Joke joke) { m_arrJokeList.add(joke); LayoutParams lparams = new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT); TextView textView = new TextView(this); setColor(textView); textView.setLayoutParams(lparams); textView.setText(joke.getJoke()); m_vwJokeLayout.addView(textView); }

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  • Write a program which works out which is the lowest priced computer in an ArrayList of computer obje

    - by Eoin
    Hello everybody! I am trying to study some java and cannot get my head around this question! Any help would be really appreciated and would help me in further studies! Thank you so much in advance! Eoin from Dublin, Ireland. ArrayList of Objects Write a program which works out which is the lowest priced computer in an ArrayList of computer objects. You should have two classes, one called ComputerTest, and the other called Computer. In the ComputerTest class you should: Have a main method which declares an ArrayList of type Computer called computerList, each element of which represents a computer. Initialise the first three entries of the ArrayList Call a static method which prints out the lowest price computer, called lowestPrice The parameter of this method is (i) an ArrayList of type Computer i.e. ArrayList data Sample output: The lowest priced computer is the Cheapo400 at 399 euro. The Computer class should have: Private instance variables: manufacturer, model, price and quality. Quality is a rating from 1 to 10. public get and set methods to retrieve and set/change the value of the four instance variables a default constructor a constructor that takes four parameters

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  • Consecutive Tables in Latex

    - by Tim
    Hi, I wonder how to place several tables consecutively in Latex? The page with the text right before the first table has a little space but not enough for the first table, so the first table is to be placed on the top of the next page, although I use "\begin{table}[!h]" for it. The second table does not fit into the place in the rest of the page of the first table, so I think I might use longtable for it to span the rest of the page and the top of the next page. Similarly, I use longtable for the third table. The latex code is as follows: ... % some text \begin{table}[!h] \caption{Table 1. \label{tab:1}} \begin{center} \begin{tabular}{c c} ... \end{tabular} \end{center} \end{table} \begin{center} \begin{longtable}{ c c } \caption{Table 2. \label{tab:2}}\\ ... \end{longtable} \end{center} \begin{center} \begin{longtable}{ c c } \caption{Table 3. \label{tab:3}}\\ ... \end{longtable} \end{center} ... % some text In the compiled pdf file it turns out that the order of the tables is messed up. The first table is placed behind the second and third one, and the second one spans the page with text before the tables and the next page with the third one following it. I would like to know how I can make the three tables appear consecutively in order, and there are no space left blank between them and between the text and the tables? Or if what I hope is not possible, what is the best strategy then? Thanks and regards! EDIT: Removing [!h] does not make improvement, the first table is still behind the second and the third.

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  • Managing aesthetic code changes in git

    - by Ollie Saunders
    I find that I make a lot of small changes to my source code, often things that have almost no functional effect. For example: Refining or correcting comments. Moving function definitions within a class for a more natural reading order. Spacing and lining up some declarations for readability. Collapsing something using multiple lines on to one. Removing an old piece of commented-out code. Correcting some inconsistent whitespace. I guess I have a formidable attention to detail in my code. But the problem is I don't know what to do about these changes and they make it difficult to switch between branches etc. in git. I find myself not knowing whether to commit the minor changes, stash them, or put them in a separate branch of little tweaks and merge that in later. None those options seems ideal. The main problem is that these sort of changes are unpredictable. If I was to commit these there would be so many commits with the message "Minor code aesthetic change.", because, the second I make such a commit I notice another similar issue. What should I do when I make a minor change, a significant change, and then another minor change? I'd like to merge the three minor changes into one commit. It's also annoying seeing files as modified in git status when the change barely warrants my attention. I know about git commit --amend but I also know that's bad practice as it makes my repo inconsistent with remotes.

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  • CSS Multiple multi-column divs

    - by accelerate
    I have a bunch of items (text, image, mixed content, etc) that I want to display. The user can define what row and what column that item appears in. For example, in row 1, there could be two items/columns, both images. In row two, there could be three items / columns, one with an image, two others as pure text. Oh, and the user may specify the width of any particular column/image/item. I have a solution that uses multiple tables that works. In essence, each row is a new table. This works for the most part. I'm wondering if I can use just divs? Now my CSS foo is lacking, and I tried to copy examples from the web, and I haven't been able to get it working. Right now I have something like this: `[for each row] [for each column] [content] ` But everything is overlapping each other. I've also tried using "position: relative", but things look even more borked. So can divs actually be used for multiple rows and different number of columns?

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  • Why doesn't this simple regex match what I think it should?

    - by Kevin Stargel
    I have a data file that looks like the following example. I've added '%' in lieu of \t, the tab control character. 1234:56% Alice Worthington alicew% Jan 1, 2010 10:20:30 AM% Closed% Development Digg: Reddit: Update%% file-one.txt% 1.1% c:/foo/bar/quux Add%% file-two.txt% 2.5.2% c:/foo/bar/quux Remove%% file-three.txt% 3.4% c:/bar/quux Update%% file-four.txt% 4.6.5.3% c:/zzz ... many more records of the above form The records I'm interested in are the lines beginning with "Update", "Add", "Remove", and so on. I won't know what the lines begin with ahead of time, or how many lines precede them. I do know that they always begin with a string of letters followed by two tabs. So I wrote this regex: generate-report-for 1234:56 | egrep "^[[:alpha:]]+\t\t.+" But this matches zero lines. Where did I go wrong? Edit: I get the same results whether I use '...' or "..." for the egrep expression, so I'm not sure it's a shell thing.

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  • SQL Server 2005 Reporting Services (x64) on Windows 2K8 -> CleanCurrentUserName() not found

    - by Steven Pardo
    I have installed SQL Server 2005 three times now on the same box. I cleaned up registry settings, files, you name it. All along I have been trying to install SQL Server 2005 Database and Reporting Services (x64) on a Windows 2008 Server. I have also applied the SP3 patch. Installing and Restarting the Server at every point. I have installed multiple instances (SQLDEV64, SQLQA64, SQLSTAGE64) of the Database and Reporting Services. I started to go through the Reporting Services Configuration manager, installing the Reporting Database along with setting up IIS. When I go test the website I get the following and there lies my question. How can I get around this error? http://localhost/reportserver Reporting Services Error -------------------------------------------------------------------------------- An internal error occurred on the report server. See the error log for more details. (rsInternalError) Method not found: 'Void Microsoft.ReportingServices.Diagnostics.UserUtil.CleanCurrentUserName()'. -------------------------------------------------------------------------------- SQL Server Reporting Services Any help would be greatly appreciated.

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  • background-color hex to js variable (jquery)

    - by Ezdaroth
    I'm kinda new to javascript and jquery and now I'm facing a problem: I need to post some data to php and one bit of the data needs to be the background color hex of div X. Jquery has css("background-color") function and with it I can get rgb value of the background into a javascript variable. The css function seems to return a string like this rgb(0, 70, 255). I couldn't find any way to get hex of the background-color (even tho it's set as hex in css). So it seems like I need to convert it. I found a function for converting rgb to hex, but it needs to be called with three different variables, r, g and b. So I would need to parse the string rgb(x,xx,xxx) into var r=x; var g=xx; var b=xxx; somehow. I tried to google parsing strings with javascript, but didn't really understand the regular expressions thing. Could someone tell me if there's a way to get background-color of div as hex, or explain how to convert the string into 3 different variables.

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  • propositional theorems

    - by gcc
    wang's theorem to prove theorems in propositonal calculus Label Sequent Comment S1: P ? Q, Q ? R, ¬R ? ¬P Initial sequent. S2: ¬P ? Q, ¬Q ? R, ¬R ? ¬P Two applications of R5. S3: ¬P ? Q, ¬Q ? R ? ¬P, R Rl. S4: ¬P, ¬Q ? R ? ¬P, R S4 and S5 are obtained from S3 with R3. Note that S4 is an axiom since P appears on both sides of the sequent ar- row at the top level. S5: Q, ¬Q ? R ? ¬P, R The other sequent generated by the ap- plication of R3. S6: Q, ¬Q ? ¬P, R S6 and S7 are obtained from S5 using R3. S7: Q, R ? ¬P, R This is an axiom. S8: Q ? ¬P, R, Q Obtained from S6 using R1. S8 is an axiom. The original sequent is now proved, since it has successfully been transformed into a set of three axioms with no unproved sequents left over. //R1,R2,R3,R4,R5 is transformation myhomework is so complicate as you can see and i must finish homework in 4 days i just want help ,can you show me how i should construct the algorithm or how i should take and store the input

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  • need advice on Zend framework Application architecture, or say approach dealing with modules

    - by simple
    Let me start with the things that I did and how am I using some things to get results I have set up modular structure as: application/ /configs /layouts /models /modules /users /profile /frontend /backend /controllers /views .... I write a plugin that does addes changes with FrontController-setModuleControllerDirectoryName() FrontController-addModuleDirectory() and It is all good I have a changed all the directories according weather admin page is requested in the url or not (it is some thing like /admin/some/some) Let's say I have a single layout for anything that is related to Profile viewing , in this case the "Profile" module. The Profile layout is divided into three parts In the layout I was pulling out the Profile/PhotoController 's index action with a action() $this->action('index', 'photo', 'profile'); Then I have faced few issues 1. Can get passed Params inside the Photo Controller when calling ( profile/profile/index); 2. found out that helper Action() is evil cause it starts another dispatching loop =) --- and now I am thinking that my approach on plugging in controllers modules into layout also evil =). anyhow how Should I deal with plugging in some controllers (another module controllers) into the layout ?

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  • Prevent Text Input expanding in IE

    - by Caroline
    Hi, I am having a problem with an input field in IE. The code is for a portlet and widths need to be dynamic as the user can place the portlet on any of the three columns in the page which all have different widths. As always it works fine in FF but not in IE. In order to make the width dyanaic I have set width="100%". Data to populate the text input comes from a DB. When the page is rendered if there is a long URL the text input expands to fill the contents in IE but in FF it just stays the same width (ie 100% of the TD that it lives in). How can I stop IE from changing the width in order to fit the contents. Setting the width to a fixed width of 100px fixes the issue but I need to have the width as a percentage in order to accommodate the layout of the portlet wherever it is put in on the page. I have tried overflow:hidden and word-wrap:break-word but I cant get either to work. Here is my input code and style sheets <td class="right" > <input type="text" class="validate[custom[url]]" value="" id="linkText" name="communicationLink" maxlength="500" maxsize="100" /> </td> .ofCommunicationsAdmin input { font-family: "Trebuchet MS"; font-size: 11px; font-weight:normal; color:#333333; overflow:hidden; } .ofCommunicationsAdmin #linkText { overflow:hidden; width:100%; border:1px #cccccc solid; background:#F4F7ED top repeat-x; } .ofCommunicationsAdmin td.right { vertical-align: top; text-align: left; }

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  • Speeding up inner-joins and subqueries while restricting row size and table membership

    - by hiffy
    I'm developing an rss feed reader that uses a bayesian filter to filter out boring blog posts. The Stream table is meant to act as a FIFO buffer from which the webapp will consume 'entries'. I use it to store the temporary relationship between entries, users and bayesian filter classifications. After a user marks an entry as read, it will be added to the metadata table (so that a user isn't presented with material they have already read), and deleted from the stream table. Every three minutes, a background process will repopulate the Stream table with new entries (i.e. whenever the daemon adds new entries after the checks the rss feeds for updates). Problem: The query I came up with is hella slow. More importantly, the Stream table only needs to hold one hundred unread entries at a time; it'll reduce duplication, make processing faster and give me some flexibility with how I display the entries. The query (takes about 9 seconds on 3600 items with no indexes): insert into stream(entry_id, user_id) select entries.id, subscriptions_users.user_id from entries inner join subscriptions_users on subscriptions_users.subscription_id = entries.subscription_id where subscriptions_users.user_id = 1 and entries.id not in (select entry_id from metadata where metadata.user_id = 1) and entries.id not in (select entry_id from stream where user_id = 1); The query explained: insert into stream all of the entries from a user's subscription list (subscriptions_users) that the user has not read (i.e. do not exist in metadata) and which do not already exist in the stream. Attempted solution: adding limit 100 to the end speeds up the query considerably, but upon repeated executions will keep on adding a different set of 100 entries that do not already exist in the table (with each successful query taking longer and longer). This is close but not quite what I wanted to do. Does anyone have any advice (nosql?) or know a more efficient way of composing the query?

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  • Why do compiled Haskell libraries see invalid static FFI storage?

    - by John Millikin
    I am using GHC 6.12.1, in Ubuntu 10.04 When I try to use the FFI syntax for static storage, only modules running in interpreted mode (ie GHCI) work properly. Compiled modules have invalid pointers, and do not work. I'd like to know whether anybody can reproduce the problem, whether this an error in my code or GHC, and (if the latter) whether it's a known issue. Given the following three modules: -- A.hs {-# LANGUAGE ForeignFunctionInterface #-} module A where import Foreign import Foreign.C foreign import ccall "&sys_siglist" siglist_a :: Ptr CString -- -- B.hs {-# LANGUAGE ForeignFunctionInterface #-} module B where import Foreign import Foreign.C foreign import ccall "&sys_siglist" siglist_b :: Ptr CString -- -- Main.hs {-# LANGUAGE ForeignFunctionInterface #-} module Main where import Foreign import Foreign.C import A import B foreign import ccall "&sys_siglist" siglist_main :: Ptr CString main = do putStrLn $ "siglist_a = " ++ show siglist_a putStrLn $ "siglist_b = " ++ show siglist_b putStrLn $ "siglist_main = " ++ show siglist_main peekSiglist "a " siglist_a peekSiglist "b " siglist_b peekSiglist "main" siglist_main peekSiglist name siglist = do ptr <- peekElemOff siglist 2 str <- maybePeek peekCString ptr putStrLn $ "siglist_" ++ name ++ "[2] = " ++ show str I would expect something like this output, where all pointer values identical and valid: $ runhaskell Main.hs siglist_a = 0x00007f53a948fe00 siglist_b = 0x00007f53a948fe00 siglist_main = 0x00007f53a948fe00 siglist_a [2] = Just "Interrupt" siglist_b [2] = Just "Interrupt" siglist_main[2] = Just "Interrupt" However, if I compile A.hs (with ghc -c A.hs), then the output changes to: $ runhaskell Main.hs siglist_a = 0x0000000040378918 siglist_b = 0x00007fe7c029ce00 siglist_main = 0x00007fe7c029ce00 siglist_a [2] = Nothing siglist_b [2] = Just "Interrupt" siglist_main[2] = Just "Interrupt"

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  • Password hashing, salt and storage of hashed values

    - by Jonathan Leffler
    Suppose you were at liberty to decide how hashed passwords were to be stored in a DBMS. Are there obvious weaknesses in a scheme like this one? To create the hash value stored in the DBMS, take: A value that is unique to the DBMS server instance as part of the salt, And the username as a second part of the salt, And create the concatenation of the salt with the actual password, And hash the whole string using the SHA-256 algorithm, And store the result in the DBMS. This would mean that anyone wanting to come up with a collision should have to do the work separately for each user name and each DBMS server instance separately. I'd plan to keep the actual hash mechanism somewhat flexible to allow for the use of the new NIST standard hash algorithm (SHA-3) that is still being worked on. The 'value that is unique to the DBMS server instance' need not be secret - though it wouldn't be divulged casually. The intention is to ensure that if someone uses the same password in different DBMS server instances, the recorded hashes would be different. Likewise, the user name would not be secret - just the password proper. Would there be any advantage to having the password first and the user name and 'unique value' second, or any other permutation of the three sources of data? Or what about interleaving the strings? Do I need to add (and record) a random salt value (per password) as well as the information above? (Advantage: the user can re-use a password and still, probably, get a different hash recorded in the database. Disadvantage: the salt has to be recorded. I suspect the advantage considerably outweighs the disadvantage.) There are quite a lot of related SO questions - this list is unlikely to be comprehensive: Encrypting/Hashing plain text passwords in database Secure hash and salt for PHP passwords The necessity of hiding the salt for a hash Clients-side MD5 hash with time salt Simple password encryption Salt generation and Open Source software I think that the answers to these questions support my algorithm (though if you simply use a random salt, then the 'unique value per server' and username components are less important).

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  • Finding Common Byte Sequences in MS SQL TEXT Column

    - by regex
    Hello All, Short Desc: I'm curious to see if I can use SQL Analysis services or some other MS SQL service to mine some data for me that will show commonalities between SQL TEXT fields in a dataset. Long Desc I am looking at a subset of data that consists of about 10,000 rows of TEXT blobs which are used as a notes column in a issue tracking (ticketing) software. I would like to use something out of the box (without having to build something) that might be able to parse through all of the rows and find commonly used byte sequences in the "Notes" column. In other words, I want to find commonly used phrases (two to three word phrases, so 9 - 20 character sections of the TEXT blob). This will help me better determine if associate's notes contain similar phrases (troubleshooting techniques) that we could standardize in our troubleshooting process flow. Closing Note I'd really rather not build an application to do this as my method will probably not be the most efficient way to do it. Hopefully all this makes sense. Please let me know in the comments if anything needs clarification. Thanks in advance for your help.

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  • Understanding MongoDB (and NoSQL in general) and how to make the best use of it

    - by Earlz
    Hello, I am beginning to think that my next project I am wanting to do would work better with a NoSQL solution. The project would either involve a ton of 2-column tables or a ton of dynamic queries with dynamically generated columns in a traditional SQL database. So I feel a NoSQL database would be much cleaner. I'm looking at MongoDB and it looks pretty promising. Anyway, I'm attempting to make sense of it all. Also, I will be using MongoMapper in Ruby. Anyway though, I'm confused as to how to layout things in such a freeform database. I've read http://stackoverflow.com/questions/2170152/nosql-best-practices and the answer there says that normalization is usually bad in a NoSQL DB. So how would be the best way of laying out say a simple blog with users, posts, and comments? My natural thought was to have three collections for each and then link them by a unique ID. But this apparently is wrong? So, what are some of the ways to lay out such a thing? My concern with the answer given in the other question is, what if the author's name changed? You'd have to go through updating a ton of posts and comments. But is this an okay thing to do with NoSQL?

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