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  • C++ - Where to throw exception?

    - by HardCoder1986
    Hello! I have some kind of an ideological question, so: Suppose I have some templated function template <typename Stream> void Foo(Stream& stream, Object& object) { ... } which does something with this object and the stream (for example, serializes that object to the stream or something like that). Let's say I also add some plain wrappers like (and let's say the number of these wrappers equals 2 or 3): void FooToFile(const std::string& filename, Object& object) { std::ifstream stream(filename.c_str()); Foo(stream, object); } So, my question is: Where in this case (ideologically) should I throw the exception if my stream is bad? Should I do this in each wrapper or just move that check to my Foo, so that it's body would look like if (!foo.good()) throw (something); // Perform ordinary actions I understand that this may be not the most important part of coding and these solutions are actually equal, but I just wan't to know "the proper" way to implement this. Thank you.

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  • Designing a database for a user/points system? (in Django)

    - by AP257
    First of all, sorry if this isn't an appropriate question for StackOverflow. I've tried to make it as generalisable as possible. I want to create a database (MySQL, site running Django) that has users, who can be allocated a certain number of points for various types of action - it's a collaborative game. My requirements are to obtain: the number of points a user has the user's ranking compared to all other users and the overall leaderboard (i.e. all users ranked in order of points) This is what I have so far, in my Django models.py file: class SiteUser(models.Model): name = models.CharField(max_length=250 ) email = models.EmailField(max_length=250 ) date_added = models.DateTimeField(auto_now_add=True) def points_total(self): points_added = PointsAdded.objects.filter(user=self) points_total = 0 for point in points_added: points_total += point.points return points_total class PointsAdded(models.Model): user = models.ForeignKey('SiteUser') action = models.ForeignKey('Action') date_added = models.DateTimeField(auto_now_add=True) def points(self): points = Action.objects.filter(action=self.action) return points class Action(models.Model): points = models.IntegerField() action = models.CharField(max_length=36) However it's rapidly becoming clear to me that it's actually quite complex (in Django query terms at least) to figure out the user's ranking and return the leaderboard of users. At least, I'm finding it tough. Is there a more elegant way to do something like this? This question seems to suggest that I shouldn't even have a separate points table - what do people think? It feels more robust to have separate tables, but I don't have much experience of database design.

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  • Updating Cells in a DataTable

    - by Maxim Z.
    I'm writing a small app to do a little processing on some cells in a CSV file I have. I've figured out how to read and write CSV files with a library I found online, but I'm having trouble: the library parses CSV files into a DataTable, but, when I try to change a cell of the table, it isn't saving the change in the table! Below is the code in question. I've separated the process into multiple variables and renamed some of the things to make it easier to debug for this question. Code Inside the loop: string debug1 = readIn.Rows[i].ItemArray[numColumnToCopyTo].ToString(); string debug2 = readIn.Rows[i].ItemArray[numColumnToCopyTo].ToString().Trim(); string debug3 = readIn.Rows[i].ItemArray[numColumnToCopyFrom].ToString().Trim(); string towrite = debug2 + ", " + debug3; readIn.Rows[i].ItemArray[numColumnToCopyTo] = (object)towrite; After the loop: readIn.AcceptChanges(); When I debug my code, I see that towrite is being formed correctly and everything's OK, except that the row isn't updated: why isn't it working? I have a feeling that I'm making a simple mistake here: the last time I worked with DataTables (quite a long time ago), I had similar problems. If you're wondering why I'm adding another comma in towrite, it's because I'm combining a street address field with a zip code field - I hope that's not messing anything up. My code is kind of messy, as I'm only trying to edit one file to make a small fix, so sorry.

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  • Setting up a git repository on a server

    - by lostInTransit
    Hi I had posted this question on superuser but didn't get a helpful response. Thought I'd try here since the question does deal with some configurations and settings for using github. I have a central server with SSO installed. All my machines are connected through the lan to this server. I have also setup a remote git repository on this server. Now what I'd like to do is make the server act as a central repository. All my employees can commit their code to the server and the server pushes it to the remote git repository. Can someone please help me out with this process? I am new to git and still learning how to use it effectively. So a step-by-step process or an existing document which I can refer to for this? Also can I integrate it with SSO in any way? The server itself is setup on a Mac and SSO uses Atlassian Crowd. Thanks.

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  • Where to create/keep secret files for license information/trials on Windows/Mac OS X/Linux?

    - by BastiBense
    I'm writing a commercial product which uses a simple registration mechanism and allows the user to use the application for a demo period before purchasing. My application must somewhere store the registration information (if entered) and/or the date of the first launch to calculate if the user is still within the demo/trail period. While I'm pretty much finished with the registration mechanism itself, I now have to find a good way to store the registration information on the user's disk. The most obvious idea would be to store the trial period in the preferences file, but since user tend to delete/tinker with those from time to time, it might be a good idea to keep the registration information in a separate, more hidden file. So here's my question: What is the best place/strategy to keep and create such hidden files on Windows, Mac OS X and Linux? Here is what came to my mind so far: Linux/Mac OS X Most Unix-like systems are rather locked down when it comes to places a user can write files to. In most cases this is only the /tmp directory and the user's home directory. I guess the easiest here is probably to create a file with a dot-prefix to make it less visible, then give it a name that won't make it obvious that it's associated with my application. Windows Probably much like Linux/Mac OS X - more recent Windows versions become more restrictive when it comes to file system permissions. Anyway, I'd like to hear your ideas and thoughs. Even better if you have already implemented something similar in the past. Thanks! Update For me the places for such files is more relevant than the discussion of the question if this way for copy protection is good or bad.

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  • Generate Spring bean definition from a Java object

    - by joeslice
    Let's suggest that I have a bean defined in Spring: <bean id="neatBean" class="com..." abstract="true">...</bean> Then we have many clients, each of which have slightly different configuration for their 'neatBean'. The old way we would do it was to have a new file for each client (e.g., clientX_NeatFeature.xml) that contained a bunch of beans for this client (these are hand-edited and part of the code base): <bean id="clientXNeatBean" parent="neatBean"> <property id="whatever" value="something"/> </bean> Now, I want to have a UI where we can edit and redefine a client's neatBean on the fly. My question is: given a neatBean, and a UI that can 'override' properties of this bean, what would be a straightforward way to serialize this to an XML file as we do [manually] today? For example, if the user set property whatever to be "17" for client Y, I'd want to generate: <bean id="clientYNeatBean" parent="neatBean"> <property id="whatever" value="17"/> </bean> Note that moving this configuration to a different format (e.g., database, other-schema'd-xml) is an option, but not really an answer to the question at hand.

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  • Pointer reference and dereference

    - by ZhekakehZ
    I have the following code: #include <iostream> char ch[] = "abcd"; int main() { std::cout << (long)(int*)(ch+0) << ' ' << (long)(int*)(ch+1) << ' ' << (long)(int*)(ch+2) << ' ' << (long)(int*)(ch+3) << std::endl; std::cout << *(int*)(ch+0) << ' ' << *(int*)(ch+1) << ' ' << *(int*)(ch+2) << ' ' << *(int*)(ch+3) << std::endl; std::cout << int('abcd') << ' ' << int('bcd') << ' ' << int('cd') << ' ' << int('d') << std::endl; } My question is why the pointer of 'd' is 100 ? I think it should be: int('d') << 24; //plus some trash on stack after ch And the question is why the second and the third line of the stdout are different ? 6295640 6295641 6295642 6295643 1684234849 6579042 25699 100 1633837924 6447972 25444 100 Thanks.

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  • Temporarily disable vim plugin without relaunching

    - by simont
    I'm using c-support in Vim. One of it's features is the automatic comment expansion. When I'm pasting code into Vim from an external editor, the comments are expanded (which gives me double-comments and messes up the paste - see below for example). I'd like to be able to disable the plugin, paste, then re-enable it, without relaunching Vim. I'm not sure if this is possible. The SO questions here, here and here all describe methods to disable plugins, but they all require me to close Vim, mess with my .vimrc or similar, and relaunch; if I have to close Vim, I might as well cat file1 >> myfile; vim myfile, then shift the lines internally, which will be just as quick. Is it possible to disable a plugin while running vim without relaunching, preferably in a way which allows me to map a hot-key toggle-plugin (so re-sourcing ~/.vimrc is alright; that's mappable to a hotkey [I imagine, haven't tried it yet])? Messed up comments: /* * * Authors: * * A Name * * * * Copyright: * * A Name, 2012 * */ EDIT: It turns out you can :set paste, :set nopaste (which, to quote :help paste, will "avoid unexpected effects [while pasting]". (See the comments). However, I'm still curious whether you can disable/enable a plugin as per the original question, so I shall leave the question open.

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  • ORDERBY "human" alphabetical order using SQL string manipulation

    - by supertrue
    I have a table of posts with titles that are in "human" alphabetical order but not in computer alphabetical order. These are in two flavors, numerical and alphabetical: Numerical: Figure 1.9, Figure 1.10, Figure 1.11... Alphabetical: Figure 1A ... Figure 1Z ... Figure 1AA If I orderby title, the result is that 1.10-1.19 come between 1.1 and 1.2, and 1AA-1AZ come between 1A and 1B. But this is not what I want; I want "human" alphabetical order, in which 1.10 comes after 1.9 and 1AA comes after 1Z. I am wondering if there's still a way in SQL to get the order that I want using string manipulation (or something else I haven't thought of). I am not an expert in SQL, so I don't know if this is possible, but if there were a way to do conditional replacement, then it seems I could impose the order I want by doing this: delete the period (which can be done with replace, right?) if the remaining figure number is more than three characters, add a 0 (zero) after the first character. This would seem to give me the outcome I want: 1.9 would become 109, which comes before 110; 1Z would become 10Z, which comes before 1AA. But can it be done in SQL? If so, what would the syntax be? Note that I don't want to modify the data itself—just to output the results of the query in the order described. This is in the context of a Wordpress installation, but I think the question is more suitably an SQL question because various things (such as pagination) depend on the ordering happening at the MySQL query stage, rather than in PHP.

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  • Memory fragmentation @ boost::asio ?

    - by Poni
    I'm pretty much stuck with a question I never got an answer for, a question which addresses an extremely important issue; memory fragmentation at boost::asio. Found nothing at the documentation nor here at SO. The functions at boost::asio, for example async_write() & async_read_some() always allocate something. (in my case it's 144 & 96 bytes respectively, in VC9 Debug build). How do I know about it? I connect a client to the "echo server" example provided with this library. I put a breakpoint at "new.cpp" at the code of "operator new(size_t size)". Then I send "123". Breakpoint is hit! Now using the stack trace I can clearly see that the root to the "new" call is coming from the async_write() & async_read_some() calls I make in the function handlers. So memory fragmentation will come sooner or later, thus I can't use ASIO, and I wish I could! Any idea? Any helpful code example?

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  • WPF A good way to make a view/edit control?

    - by Jefim
    Hi, this is just a question to discuss - what is the best way to make a view/edit control in WPF? E.g. we have an entity object Person, that has some props (name, surname, address, phone etc.). One presentation of the control would be a read-only view. And the other would have the edit view for this same person. Example: <UserControl x:Name="MyPersonEditor"> <Grid> <Grid x:Name="ViewGrid" Visibility="Visible"> <TextBlock Text="Name:"/> <TextBlock Text="{Binding Person.Name}"/> <Button Content="Edit" Click="ButtonEditStart_Click"/> </Grid> <Grid x:Name="EditGrid" Visibility="Collapsed"> <TextBlock Text="Name:"/> <TextBox Text="{Binding Person.Name}"/> <Button Content="Save" Click="ButtonEditEnd_Click"/> </Grid> </Grid> </UserControl> I hope that the idea is clear. The two options I see right now two grids with visibility switching and a TabControl without its header panel This is just a discussion question - not much trouble with it, yet I am just wondering if there are any other possibilities and elegant solutions to this.

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  • What choices do I have for a future in software development?

    - by user354892
    After graduating from college with a degree in mathematics and a minor in computer science, I took over a year to find my first programming job. I very much enjoy my work environment, but sometimes I feel like I'm not developing professionally as quickly as I am capable of. My company does mostly web programming. The project that I work on is basically a front-end for a SQL database. The entire project is (AFAIK) coded is VB.NET. I've been working on the back-end logic of the program. After some time on the job, we decided that designing web pages is not my cup of tea. It seems like the thing that I spend more time on than anything else is searching the web and SO for information about poorly documented .net and web APIs. This does not make me happy; is this normal for a programming job; I don't think it is. It really hit me the other day when i saw a question about math asked here and I didn't know the answer; I feel like my knowledge is going stale! I was previously almost hired by another company where they design graphic-intensive battle simulations for the military. I sometimes wonder what my life might be like if I had that job. I feel like my math and problem solving skills might have been a better fit at this other company. Within the wide field of software development, there are a number of directions in which to go as evidenced by the huge variety of topics discussed here on StackOverflow. I would like to feel like I'm going in the direction where I will make the most of my skills and have a satisfying career. Let me word this question as clearly as possible: given the wide breadth of the field of software development, how does it break down into sub-fields and what are the considerations for developing a software development career. I do not want to manage my career by default.

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  • loop prematurely quitting

    - by Nick Gibson
    This loop works fine but prematurely quits at times. I set a piece of code in it so that I can view the random number. It only closes prematurely when the random number is equal to the highest numbered question the user inputs (Example...a user wants 10 questions, if the random number is 10 the program quits.) I have no idea why since i have it set to if(random number <= the number of questions) for ( int loop = 1; loop < loopCount; loop++ ) { aa = r.nextInt ( 10 + 1 ); abc = ( int ) aa; String[] userAnswer = new String[x]; JOptionPane.showMessageDialog ( null, abc ); if ( abc <= x ) { for ( overValue = 1; overValue < forLoop; overValue++ ); { userAnswer[j] = JOptionPane.showInputDialog ( null, "Question " + quesNum + "\n" + questions[abc] + "\n\nA: " + a[abc] + "\nB: " + b[abc] + "\nC: " + c[abc] + "\nD: " + d[abc] ); if ( userAnswer[j].equals ( answers[j] ) ) { JOptionPane.showMessageDialog ( null, "Correct. \nThe Correct Answer is " + answers[abc] ); } else { JOptionPane.showMessageDialog ( null, "Wrong. \n The Correct Answer is " + answers[abc] ); }//else }//for }//if }//for

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  • How can I define an irregular area of the screen and find the closest point to the mouse in that area?

    - by JonathonG
    I'm looking for a method to define an area of the screen that the mouse cannot leave. I have been directed by rob mayoff, the answerer of this question, that I can use a Quartz Event Tap to detect mouse events. This puts me part of the way to the solution to THIS question. I need to define an irregular area of the screen, not just a rectangle, that the mouse cannot leave. I have been researching this and the only idea I can come up with is using a bitmap to define the irregular area, as it will be very oddly shaped. However, I am open to solutions other than using a bitmap. Since this must be done on a Mac, I've determined that I will have to use objective C / Cocoa . I need to know how to define the area and, equally importantly, how to find the closest point in the area to the mouse (so that I can move the mouse to it if the mouse tries to move outside of the area). This is similar to what the restricted area will look like: [edit:] Okay, I've come up with part of the answer to this. If I can do a basic (light-weight) point collision detection on the image mask, I can use a simple algorithm to detect the closest point to the mouse on the black area of the image. I could do this by calculating distance between a pre-defined point (P) inside the black area of the image and the target mouse position (T), taking the midpoint (M), then checking if the midpoint is inside or outside of the shape (black or white, respectively). If M is inside the shape, then move the P to M, otherwise move T to the M, continuously recalculate this until the distance between T and P is 1 pixel or less, then move the mouse to the final calculated position. All of that being said, I still need some way to test the position of the mouse against that same position on the bitmap (assume the bitmap is the same resolution as the monitor), and check if that point is black or white. All of this needs to be done in the background, without this application actually having focus, or the bitmap being visible... is this possible?

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  • CSS to Make 2 Column Content Areas

    - by Joe Majewski
    I'm trying to stray away from using tables to form the layout of my content, and I can think of two alternatives that I'd like to better learn: (1) styling list items to be side-by-side, and (2) using div blocks that float onto the same line. Both of these would have their own uses for what I'm working on. I'm already using div tags to form the entire layout of my three-column template, but what I need to do now is a bit different. In case it helps, my project can be found here. In short, here's my question; how would I style a div so that the width of it is 50% of the width of the area it occupies, rather than 50% of the width of the page? As for my other question, what would be the best approach to styling list items so that they are side-by-side? I'm working on a registration script now, and instead of using a table with "Username" on the left and the input text on the right, I can use two list items. It's late and I've been working on this project of mine for about 8 hours straight now, so I apologize if I'm asking anything confusing. Feel free to ask me any questions about what I'm trying to do. Thanks, friends. :)

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  • Sockets and COBOL

    - by kati
    I have received a job at a hospital which still uses COBOL for all organizational work, the whole (now 20 Terabyte) database (Which was a homebrew in, guess what, COBOL) is filled with the data of every patient since the last 45 (or so) years. So that was my story. Now to my question: Currently, all sockets were (from what I've seen) implemented by COBOL programs writing their data into files. These files then were read out by C++ programs (That was an additional module added in the late 1980s) and using C++ sockets sent to the database. Now this solution has stopped working as they are moving the database from COBOL to COBOL, yes - they didn't use MySQL or so - they implemented a new database - again in COBOL. I asked the guy that worked there before me (hes around 70 now) why the hell someone would do that and he told me that he is so good at COBOL that he doesn't want to write it in any other language. So far so good now my question: How can I implement socket connections in COBOL? I need to create an interface to the external COBOL database located at, for example, 192.168.1.23:283.

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  • Managing My Database in Source Control

    - by Jason
    As I am working with a new database project (within VS2008), and as I have never developed a database from scratch, I immediately began looking into how to manage a database within source control (in this case, Subversion). I found some information on SO, including this post: Keeping development databases in multiple environments in sync. One of the answers in particular pointed to a number of a links, all of which had good, useful information. I was reading a series of posts by K. Scott Allen which describe how he manages database change. From my reading (and please pardon the noobishness of my question), it seems as though the database itself is never checked into a repository. Rather, scripts that can build the database, along with test data (which is also populated from scripts) is checked into the repository. Ultimately, this means that, when a developer is testing his or her app, these scripts, which are part of the build process, are run. This ensures that the database is up-to-date, but is also run locally from every developer's machine. This makes sense to me (if I am indeed reading that correctly). However, if I am missing something, I would appreciate correction or additional guidance. In addition, another question I wanted to ask - does this also mean that I should NOT check in the mdf or ldf files that are created from Visual Studio? Thanks for any help and additional insight. Always appreciated.

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  • What is the n in O(n) when comparing sorting algorithms?

    - by Mumfi
    The question is rather simple, but I just can't find a good enough answer. I've taken a look at the most upvoted question regarding the Big-Oh notation, namely this: Plain English explanation of Big O It says there that: For example, sorting algorithms are typically compared based on comparison operations (comparing two nodes to determine their relative ordering). Now let's consider the simple bubble sort algorithm: for (int i = arr.length - 1; i > 0 ; i--) { for (int j = 0; j<i; j++) { if (arr[j] > arr[j+1]) { switchPlaces(...) } } } I know that worst case is O(n^2) and best case is O(n), but what is n exactly? If we attempt to sort an already sorted algorithm (best case), we would end up doing nothing, so why is it still O(n)? We are looping through 2 for-loops still, so if anything it should be O(n^2). n can't be the number of comparison operations, because we still compare all the elements, right? This confuses me, and I appreciate if someone could help me.

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  • POSIX Sockets: How to detect Ctrl-C sent over Telnet?

    - by ogott
    Short Question What's the right way to handle a Ctrl-C event sent over Telnet on the server side? Long Question After calling recv() on a socket, I'd like to handle some situations appropriately. One of them is to return a certain error code when Ctrl-C was received. What's the correct way to detect this? The following works, but it just doesn't seem right: size_t recv_count; static char ctrl_c[5] = {0xff, 0xf4, 0xff, 0xfd, 0x06}; recv_count = recv(socket, buffer, buffer_size, 0); if (recv_count == sizeof(ctrl_c) && memcmp(buffer, ctrl_c, sizeof(ctrl_c) == 0) { return CTRL_C_RECEIVED; } I found a comment on Ctrl-C in a side-note in this UNIX Socket FAQ: [...] (by the way, out-of-band is often used for that ctrl-C, too). As I understand, receiving out-of-band data is done using recv() with a certain flag as the last parameter. But when I'm waiting for data using recv() as I do in the code above, I can't read out-of-band data at the same time. Apart from that, I'm getting something using recv() without that oob-flag.

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  • How do browser cookie domains work?

    - by Vilx-
    Due to weird domain/subdomain cookie issues that I'm getting, I'd like to know how browsers handle cookies. If they do it in different ways, it would also be nice to know the differences. In other words - when a browser receives a cookie, that cookie MAY have a domain and a path attached to it. Or not, in which case the browser probably substitutes some defaults for them. Question 1: what are they? Later, when the browser is about to make a request, it checks its cookies and filters out the ones it should send for that request. It does so by matching them against the requests path and domain. Question 2: what are the matching rules? Added: The reason I'm asking this is because I'm interested in some edge cases. Like: Will a cookie for .example.com be available for www.example.com? Will a cookie for .example.com be available for example.com? Will a cookie for example.com be available for www.example.com? Will a cookie for example.com be available for anotherexample.com? Will www.example.com be able to set cookie for example.com? Will www.example.com be able to set cookie for www2.example.com? Will www.example.com be able to set cookie for .com? Etc. Added 2: Also, could someone suggest how I should set a cookie so that: It can be set by either www.example.com or example.com; It is accessible by both www.example.com and example.com.

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  • PHP dynamic Page-level DocBlocks

    - by Obmerk Kronen
    I was wondering if there is a way to interact with the Page-level DocBlocks. My question is more specifically about wordpress plugin development, but this question has arised also in a non-wordpress environments. The reason is mainly the possibility to easily change VERSIONS and names throughout a large project with maybe a constant definition - but that will reflect also in the docblock.. The following example Docblock is from a wordpress plugin I write - /* Plugin Name: o99 Auxilary Functions v0.4.7 Plugin URI: http://www.myurl.com Description: some simple description that nobody reads. Version: 0.4.7 Author: my cool name Author URI: http://www.ok-alsouri.com */ Is there a way to transform it into : $ver = '0.4.7'; $uri = 'http://www.myurl.com'; $desc = 'some simple description that nobody reads.'; $mcn = 'my cool name'; etc.. etc.. /* Plugin Name: o99 Auxilary Functions ($ver) Plugin URI: ($uri) Description: ($desc) Version: ($ver) Author: ($mcn) Author URI: ($$uri) */ obviously for echo to work I would need to break the docblock itself, and I can not WRITE the docblock directly into it´s own file . In shorts : can I "generate" a docblock with php itself somehow (I would think that the answer is - "no" for the page itself.. But maybe I am wrong and someone has some neat hack :-) ) Is that even possible ?

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  • Applying iterative algorithm to a set of rows from database

    - by Corvin
    Hello, this question may seem too basic to some, but please bear with be, it's been a while since I dealt with decent database programming. I have an algorithm that I need to program in PHP/MySQL to work on a website. It performs some computations iteratively on an array of objects (it ranks the objects based on their properties). In each iteration the algorithm runs through all collection a couple of times, accessing various data from different places of the whole collection. The algorithm needs several hundred iterations to complete. The array comes from a database. The straightforward solution that I see is to take the results of a database query and create an object for each row of the query, put the objects to an array and pass the array to my algorithm. However, I'm concerned with efficacy of such solution when I have to work with an array of several thousand of items because what I do is essentially mirror the results of a query to memory. On the other hand, making database query a couple of times on each iteration of the algorithm also seems wrong. So, my question is - what is the correct architectural solution for a problem like this? Is it OK to mirror the query results to memory? If not, which is the best way to work with query results in such an algorithm? Thanks!

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  • Weird send() problem (with Wireshark log)

    - by Meta
    I had another question about this issue, but I didn't ask properly, so here I go again! I'm sending a file by sending it in chunks. Right now, I'm playing around with different numbers for the size of that chunk, to see what size is the most efficient. When testing on the localhost, any chunk size seems to work fine. But when I tested it over the network, it seems like the maximum chunk size is 8191 bytes. If I try anything higher, the transfer becomes extremely, painfully, slow. To show what happens, here are the first 100 lines of Wireshark logs when I use a chunk size of 8191 bytes, and when I use a chunk size of 8192 bytes: (the sender is 192.168.0.102, and the receiver is 192.168.0.100) 8191: http://pastebin.com/E7jFFY4p 8192: http://pastebin.com/9P2rYa1p Notice how in the 8192 log, on line 33, the receiver takes a long time to ACK the data. This happens again on line 103 and line 132. I believe this delay is the root of the problem. Note that I have not modified the SO_SNDBUF option nor the TCP_NODELAY option. So my question is, why am I getting delayed ACKs when sending files in chunks of 8192 bytes, when everything works fine when using chunks of 8191 bytes? Edit: As an experiment, I tried to do the file transfer in the other direction (from 192.168.0.100 to 192.168.0.102), and surprisingly, any number worked! (Although numbers around 8000 seemed to perform the smoothest). So then the problem is with my computer! But I'm really not sure what to check for. Edit 2: Here is the pseudocode I use to send and receive data.

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  • R from java with no graphics: is it worth moving to JRI

    - by LH
    I have a system set up that's been happily running R from a java servlet, spawning processed & hooking into the process's stdin, stdout, and stderr streams, as in the second andwer to this question. After a system upgrade (that included glibc), the input is no longer reaching the R process.* Until now, 'R --vanilla --slave -f [file] ...' was working fine for me. I also have no swing dependencies right now, so I'm somewhat reluctant to add them. (I may actually not be able to add swing dependencies; am I right that using REngine automatically brings swing in? The examples import all of swing.) Are there advantages to switching to JRI? What changes would I need to make to my R script? (It currently reads from stdin and writes to stdout). I'm not finding the provided examples terribly helpful for how to use JRI in this situation. Thanks for your help & comments. *I can't even tell if the problem is data being written too soon or too late, but that's a separate issue/question; if I move to JRI I'm hoping it all becomes moot.

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  • The best way to return related data in a SQL statement

    - by Darvis Lombardo
    I have a question on the best method to get back to a piece of data that is in a related table on the other side of a many-to-many relationship table. My first method uses joins to get back to the data, but because there are multiple matching rows in the relationship table, I had to use a TOP 1 to get a single row result. My second method uses a subquery to get the data but this just doesn't feel right. So, my question is, which is the preferred method, or is there a better method? The script needed to create the test tables, insert data, and run the two queries is below. Thanks for your advice! Darvis -------------------------------------------------------------------------------------------- -- Create Tables -------------------------------------------------------------------------------------------- DECLARE @TableA TABLE ( [A_ID] [int] IDENTITY(1,1) NOT NULL, [Description] [varchar](50) NULL) DECLARE @TableB TABLE ( [B_ID] [int] IDENTITY(1,1) NOT NULL, [A_ID] [int] NOT NULL, [Description] [varchar](50) NOT NULL) DECLARE @TableC TABLE ( [C_ID] [int] IDENTITY(1,1) NOT NULL, [Description] [varchar](50) NOT NULL) DECLARE @TableB_C TABLE ( [B_ID] [int] NOT NULL, [C_ID] [int] NOT NULL) -------------------------------------------------------------------------------------------- -- Insert Test Data -------------------------------------------------------------------------------------------- INSERT INTO @TableA VALUES('A-One') INSERT INTO @TableA VALUES('A-Two') INSERT INTO @TableA VALUES('A-Three') INSERT INTO @TableB (A_ID, Description) VALUES(1,'B-One') INSERT INTO @TableB (A_ID, Description) VALUES(1,'B-Two') INSERT INTO @TableB (A_ID, Description) VALUES(1,'B-Three') INSERT INTO @TableB (A_ID, Description) VALUES(2,'B-Four') INSERT INTO @TableB (A_ID, Description) VALUES(2,'B-Five') INSERT INTO @TableB (A_ID, Description) VALUES(3,'B-Six') INSERT INTO @TableC VALUES('C-One') INSERT INTO @TableC VALUES('C-Two') INSERT INTO @TableC VALUES('C-Three') INSERT INTO @TableB_C (B_ID, C_ID) VALUES(1, 1) INSERT INTO @TableB_C (B_ID, C_ID) VALUES(2, 1) INSERT INTO @TableB_C (B_ID, C_ID) VALUES(3, 1) -------------------------------------------------------------------------------------------- -- Get result - method 1 -------------------------------------------------------------------------------------------- SELECT TOP 1 C.*, A.Description FROM @TableC C JOIN @TableB_C BC ON BC.C_ID = C.C_ID JOIN @TableB B ON B.B_ID = BC.B_ID JOIN @TableA A ON B.A_ID = A.A_ID WHERE C.C_ID = 1 -------------------------------------------------------------------------------------------- -- Get result - method 2 -------------------------------------------------------------------------------------------- SELECT C.*, (SELECT A.Description FROM @TableA A WHERE EXISTS (SELECT * FROM @TableB_C BC JOIN @TableB B ON B.B_ID = BC.B_ID WHERE BC.C_ID = C.C_ID AND B.A_ID = A.A_ID)) FROM @TableC C WHERE C.C_ID = 1

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