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  • Data structures for storing finger/stylus movements in drawing application?

    - by mattja?øb
    I have a general question about creating a drawing application, the language could be C++ or ObjectiveC with OpenGL. I would like to hear what are the best methods and practices for storing strokes data. Think of the many iPad apps that allow you to draw with your finger (or a stylus) or any other similar function on a desktop app. To summarize, the data structure must: be highly responsive to the movement store precise values (close in space / time) usable for rendering the strokes with complex textures (textures based on the dynamic of the stroke etc) exportable to a text file for saving/loading

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  • Getting Started with Component Architecture: DI?

    - by ashes999
    I just moved away from MVC towards something more component-architecture-like. I have no concept of messages yet (it's rough prototype code), objects just get internal properties and values of other classes for now. That issue aside, it seems like this is turning into an aspect-oriented-programming challenge. I've noticed that all entities with, for example, a position component will have similar properties (get/set X/Y/Z, rotation, velocity). Is it a common practice, and/or good idea, to push these behind an interface and use dependency injection to inject a generic class (eg. PositionComponent) which already has all the boiler-plate code? (I'm sure the answer will affect the model I use for message/passing)

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  • Circular movement - eliminating speed ups near Y = 0

    - by Fibericon
    I have a basic algorithm to rotate an enemy around a 200 unit radius circle with center 0. This is how I'm achieving that: if (position.Y <= 0 && position.X > -200) { position.X -= 2; position.Y = 0 - (float)Math.Sqrt((200 * 200) - (position.X * position.X)); } else { position.X += 2; position.Y = (float)Math.Sqrt((200 * 200) - (position.X * position.X)); } It does work, and I've ensured that at no point does either X or Y equal NaN. However, when Y approaches 0, it seems to go significantly faster. This surprises me, because the Y values are locked to the X, which is being incremented by a steady amount. What can I do to smooth the speed?

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  • Hide GRUB2 menu UNLESS you hold down Shift key: how to make this happen?

    - by Shasteriskt
    I have a Ubuntu - Windows 7 dual-boot set-up, and I would like to have it that my laptop would boot up Windows 7 unless I press down the Shift key right after boot and bring up the Grub2 menu from which I can choose Ubuntu. I researched on Grub2 and options for etc/default/grub and I have tried playing around with combinations with the GRUB_TIMEOUT and GRUB_HIDDEN_TIMEOUT values, but to no avail. I tried setting the GRUB_HIDDEN_TIMEOUT higher than the GRUB_TIMEOUT thinking that both countdown start simultaneously, but no - GRUB_TIMEOUT only starts after the other is done. Is this behavior achievable? If so, how?

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  • Should I try to write simple key-value storage by myself?

    - by shabunc
    I need a key-value storage in a simplest form we can think of. Keys should be some fixed-length strings, values should be some texts. This key-value storage should have an HTTP-backed API. That's basically it. As you can see, there is no big difference between such storage and some web application with some upload functionality. The thing is - it'll take few hours (including tests and coffee drinking) to write something like this. "Something like this" will be fully under my control and can be tuned on demand. Should I, in this specific case, not try to reinvent bicycles? Is it better to use some of existing NoSQL solutions. If yes, which one exactly? If, say, I'd needed something SQL-like, I won't ask and won't try to write something by myself. But with NoSQL I just don't know what is adequate and what is not.

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  • And if I ask the job interviewer for reasons to join the company?

    - by Oscar
    In job interviews I am frequently asked if I know the company, explain why do I think I would be the best choice for this company, etc and I have never liked this kinds of questions. Using your experiences in job interviewing, what do you think it would happen if I ask the interviewer to explain me why he think the company is the best company for me and why I should accept their answer? Do you think it would be a good think or bad thing to do? Edit: the idea of the question would not be to "challenge" the interviewer. The idea of the question would be to see what he thinks about the company, what values he thinks are given importance inside the company and what are the strong points of the company.

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  • Determining the angle to fire a shot when target and shooter moves, and bullet moves with shooter velocity added in

    - by Azaral
    I saw this question: Predicting enemy position in order to have an object lead its target and followed the link in the answer to stack overflow. In the stack overflow page I used the 2nd answer, the one that is a large mathematical derivation. My situation is a little different though. My first question though is will the answer provided in the stack overflow page even work to begin with, assuming the original circumstances of moving target and stationary shooter. My situation is a little different than that situation. My target moves, the shooter moves, and the bullets from the shooter start off with the velocities in x and y added to the bullets' x and y velocities. If you are sliding to the right, the bullets will remain in front of you as you move so as long as your velocity remains constant. What I'm trying to do is to get the enemy to be able to determine where they need to shoot in order to hit the player. Unless the player and enemy is stationary, the velocity from the ship adding to the velocity of the bullets will cause a miss. I'd rather like to prevent that. I used the formula in the stack overflow answer and did what I thought were the appropriate adjustments. I've been banging at this for the last four hours and I just can't make it click. It is probably something really simple and boneheaded that I am missing (that seems to be a lot of my problems lately). Here is the solution presented from the stack overflow answer: It boils down to solving a quadratic equation of the form: a * sqr(x) + b * x + c == 0 Note that by sqr I mean square, as opposed to square root. Use the following values: a := sqr(target.velocityX) + sqr(target.velocityY) - sqr(projectile_speed) b := 2 * (target.velocityX * (target.startX - cannon.X) + target.velocityY * (target.startY - cannon.Y)) c := sqr(target.startX - cannon.X) + sqr(target.startY - cannon.Y) Now we can look at the discriminant to determine if we have a possible solution. disc := sqr(b) - 4 * a * c If the discriminant is less than 0, forget about hitting your target -- your projectile can never get there in time. Otherwise, look at two candidate solutions: t1 := (-b + sqrt(disc)) / (2 * a) t2 := (-b - sqrt(disc)) / (2 * a) Note that if disc == 0 then t1 and t2 are equal. If there are no other considerations such as intervening obstacles, simply choose the smaller positive value. (Negative t values would require firing backward in time to use!) Substitute the chosen t value back into the target's position equations to get the coordinates of the leading point you should be aiming at: aim.X := t * target.velocityX + target.startX aim.Y := t * target.velocityY + target.startY Here is my code, after being corrected by Sam Hocevar (thank you again for your help!). It still doesn't work. For some reason it never enters the section of code inside the if(disc = 0) (obviously because it is always less than zero but...). However, if I plug the numbers from my game log on the enemy and player positions and velocities it outputs a valid firing solution. I have looked at the code side by side a couple of times now and I can't find any differences. There has got to be something simple I'm missing here. If someone else could look at this code and determine what is going on here I'd appreciate it. I know it's not going through that section because if it were, shouldShoot would become true and the enemy would be blasting away at the player. This section calls the function in question, CalculateShootHeading() if(shouldMove) { UseEngines(); } x += xVelocity; y += yVelocity; CalculateShootHeading(); if(shouldShoot) { ShootWeapons(); } UpdateWeapons(); This is CalculateShootHeading(). This is inside the enemy class so x and y are the enemy's x and y and the same with velocity. One output from my game log gives Player X = 2108, Player Y = -180.956, Player X velocity = 10.9949, Player Y Velocity = -6.26017, Enemy X = 1988.31, Enemy Y = -339.051, Enemy X velocity = 1.81666, Enemy Y velocity = -9.67762, 0 enemy projectiles. The output from the console tester is Bullet position = 2210.49, -239.313 and Player Position = 2210.49, -239.313. This doesn't make any sense. The only thing that could be different is the code or the input into my function in the game and I've checked that and I don't think that it is wrong as it's updated before this and never changed. float const bulletSpeed = 30.f; float const dx = playerX - x; float const dy = playerY - y; float const vx = playerXVelocity - xVelocity; float const vy = playerYVelocity - yVelocity; float const a = vx * vx + vy * vy - bulletSpeed * bulletSpeed; float const b = 2.f * (vx * dx + vy * dy); float const c = dx * dx + dy * dy; float const disc = b * b - 4.f * a * c; shouldShoot = false; if (disc >= 0.f) { float t0 = (-b - std::sqrt(disc)) / (2.f * a); float t1 = (-b + std::sqrt(disc)) / (2.f * a); if (t0 < 0.f || (t1 < t0 && t1 >= 0.f)) { t0 = t1; } if (t0 >= 0.f) { float shootx = vx + dx / t0; float shooty = vy + dy / t0; heading = std::atan2(shooty, shootx) * RAD2DEGREE; } shouldShoot = true; }

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  • Which is the appropriate content-type meta tag value?

    - by Argoron
    I have a question about the meta tag content-type. When starting to build my site (HTML+PHP+JS), I copied a lot of the meta tags over from elsewhere, and I have, amongst others, the following: <meta http-equiv="content-type" content="application/xhtml+xml; charset=iso-8859-1" /> Now, I've seen that tag is being used a lot with the value "text/html". I've been searching the web but could not find a comprehensive explanation regarding what the difference between both is. The "text/html" intuitively sounds more straightforward to me. Should I change my tag to that, or might the "application/xhtml+xml" be an equivalent solution ? Alternatively, can anyone point me to a resource where the different values for these tags are listed and explained in a clear manner? Thanks in advance

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  • arrays format (Javascript)

    - by João Melo
    i have a list of users, with minions, something like this: User52: minion10 minion12 User32: minion13 minion11 i've been keeping in an array where the "location" is the id, like this: Users: [52]User minions: [10]minion [12]minion [32]User minions: [13]minion [11]minion so i can access them easily like this: user[UserID].minions[MinionID] (ex: user[32].minions[11]) but when i print it or send it by json i get something like this: {,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,minion,,,,,,,,,,,,,,minion} but should i keep using like this or should i change to something like this: User = function(){ this.minions = ...; this.getMinion = function(value){ for(var m in this.minions){ if(this.minions[m].id == value){ return this.minions[m]; break; } } } } and get it like this: user.getMinion(MinionID); Question: i get better performance using a "short" array but using loops every time i need a minion, or using "long" arrays, but no need for loop and getting values directly from the id "name"?

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  • Calculating the force of an impact?

    - by meds
    I'm trying to figure out a way to determine the force two objects collide in. I have two vectors defining their linear velocity at the time of impact, their mass and their angular velocity. Keep in mind this is all for a 2D physics engine. I don't think it's as simple as adding up these values and figuring out if it's large enogh it makes a large impact since that doesn't take into account if the two objects are travelling in the same direction (as an example). Any ideas?

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  • Data Conversion in SQL Server

    Most of the time, you do not have to worry about implicit conversion in SQL expressions, or when assigning a value to a column. Just occasionally, though, you'll find that data gets truncated, queries run slowly, or comparisons just seem plain wrong. Robert Sheldon explains why you sometimes need to be very careful if you mix data types when manipulating values. Free trial of SQL Backup™“SQL Backup was able to cut down my backup time significantly AND achieved a 90% compression at the same time!” Joe Cheng. Download a free trial now.

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  • JavaOne 2012: JDBC Community Discussion

    - by sowmya
    At JavaOne2012, Mark Biamonte of DataDirect Technologies and Lance Andersen of Oracle organized a discussion about JDBC. To learn more about using JDBC to develop database applications, see the JDBC trail in the Java Tutorials. You will know how to use the basic JDBC API to * create tables * insert values into them * query the tables * retrieve the results of the queries * update the tables In this process, you will learn how to use simple statements and prepared statements, and see an example of a stored procedure. You will also learn how to perform transactions and how to catch exceptions and warnings. - Sowmya

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  • align to the bottom of the div [closed]

    - by dole
    I need to arange the value and the lorem ipsum text to the bottom of the div as in the following image, but everything I've tryed until now doesn't work. My html looks like this: <div class="product"> <span class="title">Lorem Ipsum</span> <div class="values"> <span class="price">$29,225</span> <span class="description">Lorem ipsum dolor sit amet, consectetur ...</span> </div> </div>

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  • I'm looking for websites with programming problems that I can practice [on hold]

    - by Spentak
    I want to become a more skilled programmer. I also want to do it through Objective-C and iOS. What websites or programs that you know of have problems that I can solve (with the answers)? I have failed some programming tests for jobs (such as "Given 2 values in a Binary Tree - how do you find the lowest common ancestor?) and I want to become a better engineer. I have developed 54 iOS/Android apps to date, but my core CS Skills apparently are rusty/bad. I have looked at TopCoder - but there aren't very many competitions going on, the website is terrible, and there does not appear to be anything that really supports Objective-C/iOS Websites?

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  • WPF Release History : Q1 2010 SP1 (version 2010.1.0422)

    Q1 2010 SP1 Changes: RadGrid Important Changes: The enumerator of RadGridView.Items now enumerates data items only (use RadGridView.Items.Groups to retrieve group items). What's New: Added support for BorderBrush and BorderThickness for GridViewRow. Editable field filter logical composition operator (And/Or). New overload of the GridViewDataContro.GetDistinctValues method that accepts the number of distinct values to return as a parameter. Group footer row now uses its Item as aggregate...Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Easy QueryBuilder - A User-Friendly Ad-Hoc Advanced Search Solution

    Constructing an easy and powerful QueryBuilder interface becomes more important for complex data grid filtering and accurate reporting services. In this article, I'll discuss how to build a query search engine using ASP.NET AJAX and dynamic SQL. The main goal is to provide an interactive interface to allow users select query attributes, operators, attribute values, and T-SQL operators so that the data context query list can be easily composed and a search engine is invoked.Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Why is there a 20 and not 21 in some versions of Planning Poker?

    - by SuffixTreeMonkey
    In Planning Poker, cards usually contain numbers of the Fibonacci sequence, which is 0,1,1,2,3,5,8,13,21,34,55 etc. However, you can see on the Wikipedia page (and this has been confirmed to me by people that work at several positions where Planning Poker is applied) in some editions the cards stray away from Fibonacci sequence after 13. They lower 21 to 20 and then continue with 40 and 100. Is there some rationale on why these values have been changed, specifically 21 to 20? (Also note that some other cards are added, such as ? and 1/2, but these are easier for me to understand, compared to the 21 - 20 shift.)

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  • Variable names for Contact Information bits

    - by RustyTheBoyRobot
    I am in the middle of refactoring code and would like to get some ideas on variable naming so that my new names clearly represent the data they hold. I have a class called ContactMethod which makes sense to me; each instance is a different way to contact someone. My problem comes when naming the properties of ContactMethod. For example, one instance might be a Fax number of 555-555-5555 while another could be an Email address of [email protected]; I've got a property called contactMethodType to hold the values "fax" or "email", but I don't know what to call the "555-555-5555" or "[email protected]" part. Has anyone here created a good generic name for this piece of contact information? (PS - the old convention was to call it a "Phone" with fields "phoneType" holding the "fax"/"email" value and "phoneId" holding the number/address. Yuck.)

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  • Data Source Security Part 2

    - by Steve Felts
    In Part 1, I introduced the default security behavior and listed the various options available to change that behavior.  One of the key topics to understand is the difference between directly using database user and password values versus mapping from WLS user and password to the associated database values.   The direct use of database credentials is relatively new to WLS, based on customer feedback.  Some of the trade-offs are covered in this article. Credential Mapping vs. Database Credentials Each WLS data source has a credential map that is a mechanism used to map a key, in this case a WLS user, to security credentials (user and password).  By default, when a user and password are specified when getting a connection, they are treated as credentials for a WLS user, validated, and are converted to a database user and password using a credential map associated with the data source.  If a matching entry is not found in the credential map for the data source, then the user and password associated with the data source definition are used.  Because of this defaulting mechanism, you should be careful what permissions are granted to the default user.  Alternatively, you can define an invalid default user to ensure that no one can accidentally get through (in this case, you would need to set the initial capacity for the pool to zero so that the pool is populated only by valid users). To create an entry in the credential map: 1) First create a WLS user.  In the administration console, go to Security realms, select your realm (e.g., myrealm), select Users, and select New.  2) Second, create the mapping.  In the administration console, go to Services, select Data sources, select your data source name, select Security, select Credentials, and select New.  See http://docs.oracle.com/cd/E24329_01/apirefs.1211/e24401/taskhelp/jdbc/jdbc_datasources/ConfigureCredentialMappingForADataSource.html for more information. The advantages of using the credential mapping are that: 1) You don’t hard-code the database user/password into a program or need to prompt for it in addition to the WLS user/password and 2) It provides a layer of abstraction between WLS security and database settings such that many WLS identities can be mapped to a smaller set of DB identities, thereby only requiring middle-tier configuration updates when WLS users are added/removed. You can cut down the number of users that have access to a data source to reduce the user maintenance overhead.  For example, suppose that a servlet has the one pre-defined, special WLS user/password for data source access, hard-wired in its code in a getConnection(user, password) call.  Every WebLogic user can reap the specific DBMS access coded into the servlet, but none has to have general access to the data source.  For instance, there may be a ‘Sales’ DBMS which needs to be protected from unauthorized eyes, but it contains some day-to-day data that everyone needs. The Sales data source is configured with restricted access and a servlet is built that hard-wires the specific data source access credentials in its connection request.  It uses that connection to deliver only the generally needed day-to-day information to any caller. The servlet cannot reveal any other data, and no WebLogic user can get any other access to the data source.  This is the approach that many large applications take and is the reasoning behind the default mapping behavior in WLS. The disadvantages of using the credential map are that: 1) It is difficult to manage (create, update, delete) with a large number of users; it is possible to use WLST scripts or a custom JMX client utility to manage credential map entries. 2) You can’t share a credential map between data sources so they must be duplicated. Some applications prefer not to use the credential map.  Instead, the credentials passed to getConnection(user, password) should be treated as database credentials and used to authenticate with the database for the connection, avoiding going through the credential map.  This is enabled by setting the “use-database-credentials” to true.  See http://docs.oracle.com/cd/E24329_01/apirefs.1211/e24401/taskhelp/jdbc/jdbc_datasources/ConfigureOracleParameters.html "Configure Oracle parameters" in Oracle WebLogic Server Administration Console Help. Use Database Credentials is not currently supported for Multi Data Source configurations.  When enabled, it turns off credential mapping on Generic and Active GridLink data sources for the following attributes: 1. identity-based-connection-pooling-enabled (this interaction is available by patch in 10.3.6.0). 2. oracle-proxy-session (this interaction is first available in 10.3.6.0). 3. set client identifier (this interaction is available by patch in 10.3.6.0).  Note that in the data source schema, the set client identifier feature is poorly named “credential-mapping-enabled”.  The documentation and the console refer to it as Set Client Identifier. To review the behavior of credential mapping and using database credentials: - If using the credential map, there needs to be a mapping for each WLS user to database user for those users that will have access to the database; otherwise the default user for the data source will be used.  If you always specify a user/password when getting a connection, you only need credential map entries for those specific users. - If using database credentials without specifying a user/password, the default user and password in the data source descriptor are always used.  If you specify a user/password when getting a connection, that user will be used for the credentials.  WLS users are not involved at all in the data source connection process.

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  • Please help me to improve Re-Sharper

    - by TATWORTH
    Re-Sharper is an excellent aid to producing good code in either C# or VB.NET. Recently through using Resharper and StyleCop, I have found three area where ReSharper needs to be improved. Please log into the YouTrack at http://youtrack.jetbrains.net and vote for the following: RSRP-268868 Improvement to removal of redundant else and invert if optimisations for enhanced stylecop compliance. When Resharper removes a redundant else, there needs to be a blank line added. Currently there is no provision to specify this. Please vote for this! RSRP-272286 Resharper Feature Request to move initialisation to static constructor Currently ReSharper offers moving initialisation of of non-static variable to a constructor. Why not offer the same for a static constructor?  Please vote for this! RSRP-272285 Expansion of Switch Statement by Resharper Currently ReSharper will fill an empty switch statement based upon an enumeration but will not add missing enumeration values to such a switch statement.   Can't code withoutCoding assistance, smart code editing and code completion for C# and VB.NET

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  • VB6 general search form

    - by SilentRage47
    I'm working on an old vb6/access2003 app which is used to handle orders, bills of materials and that sort of things. I'm thinking about creating a form that I call every time the users needs to search for something. This should work like these: Click on the field to complete, let's say name of a buyer Open new form, search for the client and click on it Return the name of the buyer to the previous form (probably the header of the order) So, I would need to pass to the new form something that identify the type of search I have to do (so what access table to open) and return some values. Is my idea correct or there something better? I would like to use only one form for all the searches, now the app works with a lot of msflexgrid for every form.

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  • Relative Positions Of Player And Enemy Are Different In XNA 3D Game

    - by CoOlDud3
    I am having a problem in my 3D Jet Fighter Game using XNA. I have a Player Jet and a few enemy drones built from a separate class. The problem is that when I set Player position and a drone's position to a height 10f in y direction. They aren't at the same height. But if i move Drone's Position up 500f in the y direction then it is pretty much close to the player. Relatively They are supposedly at the same height but with different position values. Can Any One Help Please?

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  • Structuring an input file

    - by Ricardo
    I am in the process of structuring a small program to perform some hydraulic analysis of pipe flow. As I am envisioning this, the program will read an input file, store the input parameters in a suitable way, operate on them and finally output results. I am struggling with how to structure the input file in a sane way; that is, in a way that a human can write it easily and a machine can parse it easily. A sample input file made available to me for a similar program is just a stream of comma-separated numbers that don't make much sense on their own, so that's the scenario I am trying to avoid. Though I am giving the details of my particular problem, I am more interested in general input-file structuring strategies. Is a stream of comma-separated values my best bet? Would I be better off using some sort of key:value structure? I don't know much about this, so any help will probably put me in a better track than I am now.

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  • Remote Diagnostic Agent (RDA) version 4.30

    - by inowodwo
    posted by Maurice Bauhahn Remote Diagnostic Agent (RDA) version 4.30 was released on December 11th A free download can be accessed via Knowledge Management article 314422.1 and installed in any Enterprise Performance Management 11.1.2.x environment. EPM-specific instructions are available in Knowledge Management article 1304885.1. This RDA version incorporates two new modules (EAS=Essbase Administration Services; HWA=Hyperion Web Analysis) and improvements in modules and profiles relating to twelve other Hyperion applications (EPM, EPMA, ESS, FCM, HFM, HFR, HIR, HPL, HPSV, HSS, PR, and HSV). To follow best practice, run related RDA profiles [for example: "perl rda.pl -vnSCRPp Hyperion1112_EAS"] and attach the output zip file [by default in \rda\output\] to your service requests. The comprehensive set of details provided in such output files should help technicians to avoid delays in handling service requests (by avoiding ping-pong communications resulting from repeated requests for additional values).

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  • MediaWiki plugin for dynamic content via forms

    - by Geek42
    Are there any plugins for MediaWiki that would allow me to create a page that has a form at the top that when filled in populates tags further down in the document? Say someone would put a form with "Source Server:" and "Destination Server:" fields at the top. Once those were typed in it would automatically populate those names into the content lower so that when following the instructions you could just read the docs and not have to mentally replace things, and possibly mess it all up. I'm not looking to make pages that are permanent, just ones that can have values entered before they are followed. Any suggestions?

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