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  • Effective communication in a component-based system

    - by Tesserex
    Yes, this is another question about my game engine, which is coming along very nicely, with much thanks to you guys. So, if you watched the video (or didn't), the objects in the game are composed of various components for things like position, sprites, movement, collision, sounds, health, etc. I have several message types defined for "tell" type communication between entities and components, but this only goes so far. There are plenty of times when I just need to ask for something, for example an entity's position. There are dozens of lines in my code that look like this: SomeComponent comp = (SomeComponent)entity.GetComponent(typeof(SomeComponent)); if (comp != null) comp.GetSomething(); I know this is very ugly, and I know that casting smells of improper OO design. But as complex as things are, there doesn't seem to be a better way. I could of course "hard-code" my component types and just have SomeComponent comp = entity.GetSomeComponent(); but that seems like a cop-out, and a bad one. I literally JUST REALIZED, while writing this, after having my code this way for months with no solution, that a generic will help me. SomeComponent comp = entity.GetComponent<SomeComponent>(); Amazing how that works. Anyway, this is still only a semantic improvement. My questions remain. Is this actually that bad? What's a better alternative?

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  • Is there a way to find out whether a class is a direct base of another class?

    - by user176168
    Hi I'm wondering whether there is a way to find out whether a class is a direct base of another class i.e. in boost type trait terms a is_direct_base_of function. As far as I can see boost doesn't see to support this kind of functionality which leads me to think that its impossible with the current C++ standard. The reason I want it is to do some validation checking on two macro's that are used for a reflection system to specify that one class is derived from another e.g. header.h: #define BASE A #define DERIVED B class A {}; class B : public A { #include <rtti.h> }; rtti.h: // I want to check that the two macro's are correct with a compile time assert Rtti<BASE, DERIVED> m_rtti; Although the macro's seem unnecessary in this simple example in my real world scenario rtti.h is a lot more complex. One possible avenue would be to compare the size of the this pointer with the size of a this pointer cast to the base type and some how trying to figure out whether its the size of the base class itself away or something (yeah your right I don't know how that would work either! lol)

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  • Aligning messageformat on printing a JTable.

    - by DanielFH
    I'm using this for the moment to print out my table, and it works. But I'm not really happy with the layout of the messageformatting, I would like to have both pagenumber and date in the footer, and date format aligned to the left side of the table, and page to the right. How can I do that? Been reading some stuff about overriding the PrintTable method, but seems to get pretty complex from what I've read. Hope you can help me with this issue, thank you. :) import javax.print.attribute.HashPrintRequestAttributeSet; import javax.print.attribute.PrintRequestAttributeSet; import javax.print.attribute.standard.OrientationRequested; import javax.swing.JTable; import dk.beesys.rims.ui.WindowInventory; public class Print { private static Print INSTANCE; public static Print getInstance() { if (INSTANCE == null) { INSTANCE = new Print(); } return INSTANCE; } private Print(){ } public void printList(java.awt.event.ActionEvent ignore) { String strDate = MessageFormat.format("{0,date,short} {0,time,short}", new Date()); MessageFormat header = new MessageFormat("- {0} -"); MessageFormat footer = new MessageFormat("Printed: " + strDate); PrintRequestAttributeSet aset = new HashPrintRequestAttributeSet(); aset.add(OrientationRequested.LANDSCAPE); try { WindowInventory.getInstance().getTable().print(JTable.PrintMode.FIT_WIDTH, header, footer, true, aset, true); } catch (java.awt.print.PrinterException e) { System.err.format("Cannot print %s%n", e.getMessage()); } }

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  • Is there a recommended way to communicate scientific/engineering programming to C developers?

    - by ggkmath
    Hi, I have a lot of MATLAB code that needs to get ported to C (execution speed is critical for this work) as part of a back-end process for a web application. When I attempt to outsource this code to a C developer, I assume (correct me if I'm wrong) few C developers also understand MATLAB code (things like indexing and memory management are different, etc.). I wonder if there are any C developers out there that can recommend a procedure for me to follow to best communicate what the code does? For example, should I provide the MATLAB code and explain what it's doing line by line? Or, should I just provide the math/algorithm, explain it in plain English, and let the C developer implement it with this understanding in his/her own way (e.g. can I assume the developer understands how to work with complex math (i.e. imaginary numbers), how to generate histograms, perform an FFT, etc.)? Or, is there a better method? I expect I'm not the first to need to do this, so I wonder if any C developers out there ran into this situation and can share any conventional wisdom how they'd like this task to be transferred? Thanks in advance for any comments.

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  • OpenGL ES and real world development

    - by Mark
    Hi Guys, I'm trying to learn OpenGL ES quickly (I know, I know, but these are the pressures that have been thrusted upon me) and I have been read around a fair bit, which lots of success at rendering basic models, some basic lighting and 'some' texturing success too. But this is CONSTANTLY the point at which all OpenGL ES tutorials end, they never say more of what a real life app may need. So I have a few questions that Im hoping arent too difficult. How do people get 3d models from their favorite 3d modeling tool into the iPhone/iPad application? I have seen a couple of blog posts where people have written some python scripts for tools like Blender which create .h files that you can use, is this what people seem to do everytime? Or do the "big" tooling suites (3DS, Maya, etc...) have exporting features? Say I have my model in a nice .h file, all the vertexes, texture points, etc.. are lined up, how to I make my model (say of a basic person) walk? Or to be more general, how do you animate "part" of a model (legs only, turn head, etc...)? Do they need to be a massive mash-up of many different tiny models, or can you pre-bake animations these days "into" models (somehow) Truely great 3D games for the iPhone are (im sure) unbelievably complex, but how do people (game dev firms) seem to manage that designer/developer workflow? Surely not all the animations, textures, etc... are done programatically. I hope these are not stupid questions, and in actual fact, my app that Im trying to investigate how to make is really quite simple, just a basic 3D model that I want to be able to pan/tilt around using touch. Has anyone ever done/seen anything like this that I might be able to read up on? Thanks for any help you can give, I appreciate all types of response big or small :) Cheers, Mark

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  • Best practices for (over)using Azure queues

    - by John
    Hi, I'm in the early phases of designing an Azure-based application. One of the things that attracts me to Azure is the scalability, given the variability of the demand I'm likely to expect. As such I'm trying to keep things loosely coupled so I can add instances when I need to. The recommendations I've seen for architecting an application for Azure include keeping web role logic to a minimum, and having processing done in worker roles, using queues to communicate and some sort of back-end store like SQL Azure or Azure Tables. This seems like a good idea to me as I can scale up either or both parts of the application without any issue. However I'm curious if there are any best practices (or if anyone has any experiences) for when it's best to just have the web role talk directly to the data store vs. sending data by the queue? I'm thinking of the case where I have a simple insert to do from the web role - while I could set this up as a message, send it on the queue, and have a worker role pick it up and do the insert, it seems like a lot of double-handling. However I also appreciate that it may be the case that this is better in the long run, in case the web role gets overwhelmed or more complex logic ends up being required for the insert. I realise this might be a case where the answer is "it depends entirely on the situation, check your perf metrics" - but if anyone has any thoughts I'd be very appreciative! Thanks John

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  • Modify Gridview as it's being rendered through javascript

    - by JonF
    I'm trying to modify a field in each row of my gridview as it is rendered. I need to modify it with client side Javascript. I'm somewhat new to asp.net, but I think I should be doing something with clientscriptmanager. I came up with a simple scenario which is basically what I want to do to avoid getting bogged down in the details. If I could accomplish the following I could accomplish my goal. Say I have a grid view of names and salaries. I want to double each persons salary before displaying it. Obviously I can do it in the code behind, but due to the nature of the more complex actual thing I'm doing, I need to do it in javascript <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" onrowdatabound="GridView1_RowDataBound" > <Columns> <asp:BoundField HeaderText="Full Name" DataField="Name" ></asp:BoundField> <asp:BoundField HeaderText="Salary" DataField="Salary" /> </Columns>

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  • Dictionaries with more than one key per value in Python

    - by nickname
    I am attempting to create a nice interface to access a data set where each value has several possible keys. For example, suppose that I have both a number and a name for each value in the data set. I want to be able to access each value using either the number OR the name. I have considered several possible implementations: Using two separate dictionaries, one for the data values organized by number, and one for the data values organized by name. Simply assigning two keys to the same value in a dictionary. Creating dictionaries mapping each name to the corresponding number, and vice versa Attempting to create a hash function that maps each name to a number, etc. (related to the above) Creating an object to encapsulate all three pieces of data, then using one key to map dictionary keys to the objects and simply searching the dictionary to map the other key to the object. None of these seem ideal. The first seems ugly and unmaintainable. The second also seems fragile. The third/fourth seem plausible, but seem to require either much manual specification or an overly complex implementation. Finally, the fifth loses constant-time performance for one of the lookups. In C/C++, I believe that I would use pointers to reference the same piece of data from different keys. I know that the problem is rather similar to a database lookup problem by a non-key column, however, I would like (if possible), to maintain the approximate O(1) performance of Python dictionaries. What is the most Pythonic way to achieve this data structure?

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  • How to marshal an object and its content (also objects)

    - by Waldo Spek
    I have a question for which I suspect the answer is a bit complex. At this moment I am programming a DLL (class library) in C#. This DLL uses a 3rd party library and therefore deals with 3rd party objects of which I do not have the source code. Now I am planning to create another DLL, which is going to be used in a later stadium in my application. This second DLL should use the 3rd party objects (with corresponding object states) created by the first DLL. Luckily the 3rd party objects extend the MarshalByRefObject class. I can marshal the objects using System.Runtime.Remoting.Marshal(...). I then serialize the objects using a BinaryFormatter and store the objects as a byte[] array. All goes well. I can deserialize and unmarshal in a the opposite way and end up with my original 3rd party objects...so it appears... Nevertheless, when calling methods on my 3rd party deserialized objects I get object internal exceptions. Normally these methods return other 3rd party objects, but (obviously - I guess) now these objects are missing because they weren't serialized. Now my global question: how would I go about marshalling/serializing all the objects which my 3rd party objects reference...and cascade down the "reference tree" to obtain a full and complete serialized object? Right now my guess is to preprocess: obtain all the objects and build my own custom object and serialize it. But I'm hoping there is some other way...

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  • How to write automated tests for SQL queries?

    - by James
    The current system we are adopting at work is to write some extremely complex queries which perform multiple calculations and have multiple joins / sub-queries. I don't think I am experienced enough to say if this is correct or not so I am agreeing and attempting to function with this system as it has clear benefits. The problem we are having at the moment is that the person writing the queries makes a lot of mistakes and assumes everything is correct. We have now assigned a tester to analyse all of the queries but this still proves extremely time consuming and stressful. I would like to know how we could create an automated procedure (without specifically writing it with code if possible as I can work out how to do that the long way) to verify a set of 10+ different inputs, verify the output data and say if the calculations are correct. I know I could write a script using specific data in the database and create a script using c# (the db is SQL Server) and verify all the values coming out but I would like to know what the official "standard" is as my experience is lacking in this area and I would like to improve. I am happy to add more information if required, add a comment if necessary. Thank you. Edit: I am using c#

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  • Why would an image (the Mandelbrot) be skewed and wrap around?

    - by Sean D
    So I just wrote a little snippet to generate the Mandelbrot fractal and imagine my surprise when it came out all ugly and skewed (as you can see at the bottom). I'd appreciate a point in the direction of why this would even happen. It's a learning experience and I'm not looking for anyone to do it for me, but I'm kinda at a dead end debugging it. The offending generation code is: module Mandelbrot where import Complex import Image main = writeFile "mb.ppm" $ imageMB 1000 mandelbrotPixel x y = mb (x:+y) (0:+0) 0 mb c x iter | magnitude x > 2 = iter | iter >= 255 = 255 | otherwise = mb c (c+q^2) (iter+1) where q = x --Mandelbrot --q = (abs.realPart $ x) :+ (abs.imagPart $ x) --Burning Ship argandPlane x0 x1 y0 y1 width height = [(x,y)| y<-[y1,(y1-dy)..y0], --traverse from x<-[x0,(x0+dx)..x1]] --top-left to bottom-right where dx = (x1 - x0)/width dy = (y1 - y0)/height drawPicture :: (a->b->c)->(c->Colour)->[(a,b)]->Image drawPicture function colourFunction plane = map (colourFunction.uncurry function) plane imageMB s = createPPM s s $ drawPicture mandelbrotPixel (\x->[x,x,x]) $ argandPlane (-1.8) (-1.7) (0.02) 0.055 s' s' where s' = fromIntegral s And the image code (which I'm fairly confident in) is: module Image where type Colour = [Int] type Image = [Colour] createPPM :: Int -> Int -> Image -> String createPPM w h i = concat ["P3 ", show w, " ", show h, " 255\n", unlines.map (unwords.map show) $ i]

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  • Is there a more elegant solution than an if-statement with no else clause?

    - by Jay
    In the following code, if Control (the element that trigers Toggle's first OL) is not Visible it should be set Visible and all other Controls (Controls[i]) so be Hidden. .js function Toggle(Control){ var Controls=document.getElementsByTagName("ol",document.getElementById("Quote_App")); var Control=Control.getElementsByTagName("ol")[0]; if(Control.style.visibility!="visible"){ for(var i=0;i<Controls.length;i++){ if(Controls[i]!=Control){ Reveal("hide",20,0.3,Controls[i]); }else{ Reveal("show",20,0.3,Control); }; }; }else{ Reveal("hide",20,0.3,Control); }; }; Although the function [Toggle] works fine, it is actually setting Controls[i] to Hidden even if it is already. This is easily rectified by adding an If statement as in the code below, surely there is a more elegant solution, maybe a complex If condition? .js function Toggle(Control){ var Controls=document.getElementsByTagName("ol",document.getElementById("Quote_App")); var Control=Control.getElementsByTagName("ol")[0]; if(Control.style.visibility!="visible"){ for(var i=0;i<Controls.length;i++){ if(Controls[i]!=Control){ if(Controls[i].style.visibility=="visible"){ Reveal("hide",20,0.3,Controls[i]); }; }else{ Reveal("show",20,0.3,Control); }; }; }else{ Reveal("hide",20,0.3,Control); }; }; Your help is appreciated always.

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  • How to detect what allowed character in current Regular Expression by using JavaScript?

    - by Soul_Master
    In my web application, I create some framework that use to bind model data to control on page. Each model property has some rule like string length, not null and regular expression. Before submit page, framework validate any binded control with defined rules. So, I want to detect what character that is allowed in each regular expression rule like the following example. "^[0-9]$" allow only digit characters like 1, 2, 3. "^[a-zA-Z_][a-zA-Z_-0-9]+$" allow only a-z, - and _ characters However, this function should not care about grouping, positioning of allowed character. It just tells about possible characters only. By the way, complex regular expression like find two words near(\bword1\W+(?:\w+\W+){1,6}?word2\b) must be ignore to verify and it should return any characters is possible. Do you have any idea for creating this function? PS. I know it easy to create specified function like numeric only for allowing only digit characters. But I need share/reuse same piece of code both data tier(contains all model validator) and UI tier without modify anything. Thanks

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  • GridView ObjectDataSource LINQ Paging and Sorting using multiple table query.

    - by user367426
    I am trying to create a pageing and sorting object data source that before execution returns all results, then sorts on these results before filtering and then using the take and skip methods with the aim of retrieving just a subset of results from the database (saving on database traffic). this is based on the following article: http://www.singingeels.com/Blogs/Nullable/2008/03/26/Dynamic_LINQ_OrderBy_using_String_Names.aspx Now I have managed to get this working even creating lambda expressions to reflect the sort expression returned from the grid even finding out the data type to sort for DateTime and Decimal. public static string GetReturnType<TInput>(string value) { var param = Expression.Parameter(typeof(TInput), "o"); Expression a = Expression.Property(param, "DisplayPriceType"); Expression b = Expression.Property(a, "Name"); Expression converted = Expression.Convert(Expression.Property(param, value), typeof(object)); Expression<Func<TInput, object>> mySortExpression = Expression.Lambda<Func<TInput, object>>(converted, param); UnaryExpression member = (UnaryExpression)mySortExpression.Body; return member.Operand.Type.FullName; } Now the problem I have is that many of the Queries return joined tables and I would like to sort on fields from the other tables. So when executing a query you can create a function that will assign the properties from other tables to properties created in the partial class. public static Account InitAccount(Account account) { account.CurrencyName = account.Currency.Name; account.PriceTypeName = account.DisplayPriceType.Name; return account; } So my question is, is there a way to assign the value from the joined table to the property of the current table partial class? i have tried using. from a in dc.Accounts where a.CompanyID == companyID && a.Archived == null select new { PriceTypeName = a.DisplayPriceType.Name}) but this seems to mess up my SortExpression. Any help on this would be much appreciated, I do understand that this is complex stuff.

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  • What's the best approach for getting into VS2010, C# 4, and WPF if my background is in C++/MFC

    - by Canacourse
    All my past programming experience has been in C++ on VS2003/8, Mostly service based and completely self taught. 2 Years ago I had to create my first real GUI app and (Foolishly) choose MFC. I got the app working but it took a long time & was a bit of a nightmare to learn MCF (and its many shortcomings) but I ended up with a reliable workable app which was difficult to change or extend. Again I have to create another GUI app more complex than the first and again this will be created from scratch and will only ever be used on windows. I had put off learning C# for a long time but not wishing to re-visit MFC have decided that the new application with be birthed in VS2010 and WPF 4 will be the midwife. Trying to avoid the several expensive (Time wise) mistakes I made previously. Im looking for for good books/tutorials on the current versions of C# 4 & WPF 4 and also general advice on the best approach. The application will do several things one of them would persisting info in a SQL DB. So Im thinking LINQ for that? Please chip in...

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  • How to write an R function that evaluates an expression within a data-frame

    - by Prasad Chalasani
    Puzzle for the R cognoscenti: Say we have a data-frame: df <- data.frame( a = 1:5, b = 1:5 ) I know we can do things like with(df, a) to get a vector of results. But how do I write a function that takes an expression (such as a or a > 3) and does the same thing inside. I.e. I want to write a function fn that takes a data-frame and an expression as arguments and returns the result of evaluating the expression "within" the data-frame as an environment. Never mind that this sounds contrived (I could just use with as above), but this is just a simplified version of a more complex function I am writing. I tried several variants ( using eval, with, envir, substitute, local, etc) but none of them work. For example if I define fn like so: fn <- function(dat, expr) { eval(expr, envir = dat) } I get this error: > fn( df, a ) Error in eval(expr, envir = dat) : object 'a' not found Clearly I am missing something subtle about environments and evaluation. Is there a way to define such a function?

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  • What wrapper class in C++ should I use for automated resource management?

    - by Vilx-
    I'm a C++ amateur. I'm writing some Win32 API code and there are handles and weirdly compositely allocated objects aplenty. So I was wondering - is there some wrapper class that would make resource management easier? For example, when I want to load some data I open a file with CreateFile() and get a HANDLE. When I'm done with it, I should call CloseHandle() on it. But for any reasonably complex loading function there will be dozens of possible exit points, not to mention exceptions. So it would be great if I could wrap the handle in some kind of wrapper class which would automatically call CloseHandle() once execution left the scope. Even better - it could do some reference counting so I can pass it around in and out of other functions, and it would release the resource only when the last reference left scope. The concept is simple - but is there something like that in the standard library? I'm using Visual Studio 2008, by the way, and I don't want to attach a 3rd party framework like Boost or something.

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  • How to optimize paging for large in memory database

    - by snakefoot
    I have an application where the entire database is implemented in memory using a stl-map for each table in the database. Each item in the stl-map is a complex object with references to other items in the other stl-maps. The application works with a large amount of data, so it uses more than 500 MByte RAM. Clients are able to contact the application and get a filtered version of the entire database. This is done by running through the entire database, and finding items relevant for the client. When the application have been running for an hour or so, then Windows 2003 SP2 starts to page out parts of the RAM for the application (Eventhough there is 16 GByte RAM on the machine). After the application have been partly paged out then a client logon takes a long time (10 mins) because it now generates a page fault for each pointer lookup in the stl-map. I can see it is possible to tell Windows to lock memory in RAM, but this is generally only recommended for device drivers, and only for "small" amounts of memory. I guess a poor mans solution could be to loop through the entire memory database, and thus tell Windows we are still interested in keeping the datamodel in RAM. I guess another poor mans solution could be to disable the pagefile completely on Windows. I guess the expensive solution would be a SQL database, and then rewrite the entire application to use a database layer. Then hopefully the database system will have implemented means to for fast access. Are there other more elegant solutions ?

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  • PHP - Find a string in file then show it's line number

    - by xZero
    I have an application which needs to open the file, then find string in it, and print a line number where is string found. For example, file example.txt contains few hashes: APLF2J51 1a79a4d60de6718e8e5b326e338ae533 EEQJE2YX 66b375b08fc869632935c9e6a9c7f8da O87IGF8R c458fb5edb84c54f4dc42804622aa0c5 APLF2J51 B7TSW1ZE 1e9eea56686511e9052e6578b56ae018 EEQJE2YX affb23b07576b88d1e9fea50719fb3b7 So, I want to PHP search for "1e9eea56686511e9052e6578b56ae018" and print out its line number, in this case 4. Please note that there are will not be multiple hashes in file. I found a few codes over Internet, but none seem to work. I tried this one: <?PHP $string = "1e9eea56686511e9052e6578b56ae018"; $data = file_get_contents("example.txt"); $data = explode("\n", $data); for ($line = 0; $line < count($data); $line++) { if (strpos($data[$line], $string) >= 0) { die("String $string found at line number: $line"); } } ?> It just says that string is found at line 0.... Which is not correct.... Final application is much more complex than that... After it founds line number, it should replace string which something else, and save changes to file, then goes further processing.... Thanks in advance :)

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  • workaround for ORA-03113: end-of-file on communication channel

    - by Jefferstone
    The call to TEST_FUNCTION below fails with "ORA-03113: end-of-file on communication channel". A workaround is presented in TEST_FUNCTION2. I boiled down the code as my actual function is far more complex. Tested on Oracle 11G. Anyone have any idea why the first function fails? CREATE OR REPLACE TYPE "EMPLOYEE" AS OBJECT ( employee_id NUMBER(38), hire_date DATE ); CREATE OR REPLACE TYPE "EMPLOYEE_TABLE" AS TABLE OF EMPLOYEE; CREATE OR REPLACE FUNCTION TEST_FUNCTION RETURN EMPLOYEE_TABLE IS table1 EMPLOYEE_TABLE; table2 EMPLOYEE_TABLE; return_table EMPLOYEE_TABLE; BEGIN SELECT CAST(MULTISET ( SELECT user_id, created FROM all_users WHERE LOWER(username) < 'm' ) AS EMPLOYEE_TABLE) INTO table1 FROM dual; SELECT CAST(MULTISET ( SELECT user_id, created FROM all_users WHERE LOWER(username) >= 'm' ) AS EMPLOYEE_TABLE) INTO table2 FROM dual; SELECT CAST(MULTISET ( SELECT employee_id, hire_date FROM TABLE(table1) UNION SELECT employee_id, hire_date FROM TABLE(table2) ) AS EMPLOYEE_TABLE) INTO return_table FROM dual; RETURN return_table; END TEST_FUNCTION; CREATE OR REPLACE FUNCTION TEST_FUNCTION2 RETURN EMPLOYEE_TABLE IS table1 EMPLOYEE_TABLE; table2 EMPLOYEE_TABLE; return_table EMPLOYEE_TABLE; BEGIN SELECT CAST(MULTISET ( SELECT user_id, created FROM all_users WHERE LOWER(username) < 'm' ) AS EMPLOYEE_TABLE) INTO table1 FROM dual; SELECT CAST(MULTISET ( SELECT user_id, created FROM all_users WHERE LOWER(username) >= 'm' ) AS EMPLOYEE_TABLE) INTO table2 FROM dual; WITH combined AS ( SELECT employee_id, hire_date FROM TABLE(table1) UNION SELECT employee_id, hire_date FROM TABLE(table2) ) SELECT CAST(MULTISET ( SELECT * FROM combined ) AS EMPLOYEE_TABLE) INTO return_table FROM dual; RETURN return_table; END TEST_FUNCTION2; SELECT * FROM TABLE (TEST_FUNCTION()); -- Throws exception ORA-03113. SELECT * FROM TABLE (TEST_FUNCTION2()); -- Works

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  • Linq - reuse expression on child property

    - by user175528
    Not sure if what I am trying is possible or not, but I'd like to reuse a linq expression on an objects parent property. With the given classes: class Parent { int Id { get; set; } IList<Child> Children { get; set; } string Name { get; set; } } class Child{ int Id { get; set; } Parent Dad { get; set; } string Name { get; set; } } If i then have a helper Expression<Func<Parent,bool> ParentQuery() { Expression<Func<Parent,bool> q = p => p.Name=="foo"; } I then want to use this when querying data out for a child, along the lines of: using(var context=new Entities.Context) { var data=context.Child.Where(c => c.Name=="bar" && c.Dad.Where(ParentQuery)); } I know I can do that on child collections: using(var context=new Entities.Context) { var data=context.Parent.Where(p => p.Name=="foo" && p.Childen.Where(childQuery)); } but cant see any way to do this on a property that isnt a collection. This is just a simplified example, actually the ParentQuery will be more complex and I want to avoid having this repeated in multiple places as rather than just having 2 layers I'll have closer to 5 or 6, but all of them will need to reference the parent query to ensure security.

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  • How best to implement support for multiple devices in a web application.

    - by Kabeer
    Hello. My client would like a business application to support 'every possible device'. The application in question is essentially a web application and 'every possible device', I believe encompasses mobile phones, netbooks, ipad, other browser supporting devices, etc. The application is somewhat complex w.r.t. the data it captures and other functions it performs (reporting). If I continue to honor increasing complexity in the application, I guess there are more chances of it not working on other devices. I'd like to know how web applications support multiple devices conventionally? Are there multiple versions of presentation layer (like many times I find m.website.com dedicated for mobile devices)? Further, if my application is to take advantage of Java Script, RIA (Flash, SilverLight) then what are the consequences and workarounds? Mine is a .Net based application and the stack also contains Ext JS Java Script library. While I would like to use it for sure, considering that I would be doing a lot of work in Java Script rather than HTML, this could be a problem. The answer to the above could be descriptive. If there is something already prescribed out there, please share the link(s). Thanks.

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  • Thread mutex behaviour

    - by Alberteddu
    Hi there, I'm learning C. I'm writing an application with multiple threads; I know that when a variable is shared between two or more threads, it is better to lock/unlock using a mutex to avoid deadlock and inconsistency of variables. This is very clear when I want to change or view one variable. int i = 0; /** Global */ static pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER; /** Thread 1. */ pthread_mutex_lock(&mutex); i++; pthread_mutex_unlock(&mutex); /** Thread 2. */ pthread_mutex_lock(&mutex); i++; pthread_mutex_unlock(&mutex); This is correct, I think. The variable i, at the end of the executions, contains the integer 2. Anyway, there are some situations in which I don't know exactly where to put the two function calls. For example, suppose you have a function obtain(), which returns a global variable. I need to call that function from within the two threads. I have also two other threads that call the function set(), defined with a few arguments; this function will set the same global variable. The two functions are necessary when you need to do something before getting/setting the var. /** (0) */ /** Thread 1, or 2, or 3... */ if(obtain() == something) { if(obtain() == somethingElse) { // Do this, sometimes obtain() and sometimes set(random number) (1) } else { // Do that, just obtain(). (2) } } else { // Do this and do that (3) // If # of thread * 3 > 10, then set(3*10) For example. (4) } /** (5) */ Where I have to lock, and where I have to unlock? The situation can be, I think, even more complex. I will appreciate an exhaustive answer. Thank you in advance. —Alberto

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  • Terminate function on System.in .. possible?

    - by Ronald
    I am currently working on a project where I have to make an agent to interact with a server. Each 50ms, the server will receive the last thing I outputted to System.out and send me a new set of lines as a 'state' through the System.in printstream to analyze and send my next message to System.out. Also, if the server receives multiple outputs from me, it only regards the most recent one. .. As for my question: My program originally constructed a tree and then analyzed each leaf node to see which would be optimal, and then waited around for the next input, but I can recursively do a deeper tree search that would make my output 'better' (and again and again to keep returning a better result). Using this and the fact that if the server receives multiple outputs, it only takes the most recent one, I could do each level, print my result and start the next level. But here comes my problem... I can't be stuck in some complex algorithm while I am supposed to receiving the next input as I will then miss it. So I was wondering if there is a way to cancel anything else I am doing when I receive something via System.in and then go back to the beginning of the function and start the search again with the new set of input (and rinse and repeat..) I hope this all makes sense, Thank ye all

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  • How Best to Replace Ugly Queries and Dynamic PL/SQL with C#?

    - by Mike
    Hi, I write a lot of one-off Oracle SQL queries (in Toad), and sometimes they can get complex, involving lots of unions, joins, and subqueries, and sometimes requiring dynamic SQL. That is, sometimes SQL queries require set based processing along with significant procedural processing. This is what PL/SQL is custom made for, but as a language it does not begin to compare to C#. Now and then I convert a PL/SQL procedure to C#, and am always amazed at how much cleaner and easier to both read and write the C# version is. The C# program might for example construct a SQL query string piece by piece and/or run several queries and process them as needed. The C# version is usually much faster as well, which must mean that I'm not very good at PL/SQL either. I do not currently have access to LINQ. My question is, how best to package all these little C# programs, which are really just mini reports, that is, replacements for ugly SQL queries? Right now I'm actually using NUnit to hold them, and calling each report a [Test], even though they aren't really tests. NUnit just happens to provide a convenient packaging framework.

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