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  • How to find an XPath query to Element/Element without namespaces (XmlSerializer, fragment)?

    - by Veksi
    Assume this simple XML fragment in which there may or may not be the xml declaration and has exactly one NodeElement as a root node, followed by exactly one other NodeElement, which may contain an assortment of various number of different kinds of elements. <?xml version="1.0"> <NodeElement xmlns="xyz"> <NodeElement xmlns=""> <SomeElement></SomeElement> </NodeElement> </NodeElement> How could I go about selecting the inner NodeElement and its contents without the namespace? For instance, "//*[local-name()='NodeElement/NodeElement[1]']" (and other variations I've tried) doesn't seem to yield results. As for in general the thing that I'm really trying to accomplish is to Deserialize a fragment of a larger XML document contained in a XmlDocument. Something like the following var doc = new XmlDocument(); doc.LoadXml(File.ReadAllText(@"trickynodefile.xml")); //ReadAllText to avoid Unicode trouble. var n = doc.SelectSingleNode("//*[local-name()='NodeElement/NodeElement[1]']"); using(var reader = XmlReader.Create(new StringReader(n.OuterXml))) { var obj = new XmlSerializer(typeof(NodeElementNodeElement)).Deserialize(reader); I believe I'm missing just the right XPath expression, which seem to be rather elusive. Any help much appreciated!

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  • How do I stop Chrome from yellowing my site's input boxes?

    - by davebug
    Among other text and visual aids on a form submission, post-validation, I'm coloring my input boxes red to signify the interactive area needing attention. On Chrome (and for Google Toolbar users) the auto-fill feature re-colors my input forms yellow. Here's the complex issue: I want auto-complete allowed on my forms, as it speeds users logging in. I am going to check into the ability to turn the autocomplete attribute to off if/when there's an error triggered, but it is a complex bit of coding to programmatically turn off the auto-complete for the single effected input on a page. This, to put it simply, would be a major headache. So to try to avoid that issue, is there any simpler method of stopping Chrome from re-coloring the input boxes? [edit] I tried the !important suggestion below and it had no effect. I have not yet checked Google Toolbar to see if the !important attribute woudl work for that. As far as I can tell, there isn't any means other than using the autocomplete attribute (which does appear to work).

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  • Complex SQL design, help/advice needed

    - by eugeneK
    Hi, i have few questions for SQL gurus in here ... Briefly this is ads management system where user can define campaigns for different countries, categories, languages. I have few questions in mind so help me with what you can. Generally i'm using ASP.NET and i want to cache all result set of certain user once he asks for statistics for the first time, this way i will avoid large round-trips to server. any help is welcomed Click here for diagram with all details you need for my questions 1.Main issue of this application is to show to the user how many clicks/impressions were and how much money he spent on campaign. What is the easiest way to get this information for him? I will also include filtering by date, date ranges and few other params in this statistics table. 2.Other issue is what happens when user will try to edit campaign. Old campaign will die this means if user set 0.01$ as campaignPPU (pay-per-unit) and next day updates it to 0.05$ all will be reset to 0.05$. 3.If you could re-design some parts of table design so it would be more flexible and easier to modify, how would you do it? Thanks... sorry for so large job but it may interest some SQL guys in here

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  • Strict pointer aliasing: is access through a 'volatile' pointer/reference a solution?

    - by doublep
    On the heels of a specific problem, a self-answer and comments to it, I'd like to understand if it is a proper solution, workaround/hack or just plain wrong. Specifically, I rewrote code: T x = ...; if (*reinterpret_cast <int*> (&x) == 0) ... As: T x = ...; if (*reinterpret_cast <volatile int*> (&x) == 0) ... with a volatile qualifier to the pointer. Let's just assume that treating T as int in my situation makes sense. Does this accessing through a volatile reference solve pointer aliasing problem? For a reference, from specification: [ Note: volatile is a hint to the implementation to avoid aggressive optimization involving the object because the value of the object might be changed by means undetectable by an implementation. See 1.9 for detailed semantics. In general, the semantics of volatile are intended to be the same in C++ as they are in C. — end note ] EDIT: The above code did solve my problem at least on GCC 4.5.

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  • Overriding Code Igniter 2.14's global_xss_filtering settting

    - by user2353007
    I have created the following file at: application/core/MY_Security.php <?php if ( ! defined('BASEPATH')) exit('No direct script access allowed'); /* * Does not work with global xss */ class MY_Security extends CI_Security { function xss_clean($str, $is_image = FALSE) { $CI =& get_instance(); $CI->load->library('My_cleaner'); return $CI->my_cleaner->clean_html($str); } } this works great for $this-input-post('post_var', TRUE); and $this-security-xss_clean($input); It is working very well except when I go into application/config/config.php and change $config['global_xss_filtering] = FALSE; to $config['global_xss_filtering] = TRUE; in that case, I just get a white page on every controllers action/function. Does anybody know what else I have to change to get global_xss_filtering = TRUE; to work when overriding the xss_clean function in system/core/Security.php through application/core/MY_Security.php? I'm guessing it might be something with the loader but I'm not sure where to start. The next option is to just replace the function in the system/core/Security.php file which I am trying to avoid. Thanks.

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  • DDD: Enum like entities

    - by Chris
    Hi all, I have the following DB model: **Person table** ID | Name | StateId ------------------------------ 1 Joe 1 2 Peter 1 3 John 2 **State table** ID | Desc ------------------------------ 1 Working 2 Vacation and domain model would be (simplified): public class Person { public int Id { get; } public string Name { get; set; } public State State { get; set; } } public class State { private int id; public string Name { get; set; } } The state might be used in the domain logic e.g.: if(person.State == State.Working) // some logic So from my understanding, the State acts like a value object which is used for domain logic checks. But it also needs to be present in the DB model to represent a clean ERM. So state might be extended to: public class State { private int id; public string Name { get; set; } public static State New {get {return new State([hardCodedIdHere?], [hardCodeNameHere?]);}} } But using this approach the name of the state would be hardcoded into the domain. Do you know what I mean? Is there a standard approach for such a thing? From my point of view what I am trying to do is using an object (which is persisted from the ERM design perspective) as a sort of value object within my domain. What do you think? Question update: Probably my question wasn't clear enough. What I need to know is, how I would use an entity (like the State example) that is stored in a database within my domain logic. To avoid things like: if(person.State.Id == State.Working.Id) // some logic or if(person.State.Id == WORKING_ID) // some logic

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  • CSS3PIE issues in IE6 and 8

    - by Gordon
    I'm using CSS3PIE to apply some rounded corners to elements in Internet Explorer that will get them by stylesheet in other browsers. I've run into some issues with it though. In IE8, I discovered that any element that had the PIE behaviour would behave strangely. The container would jump a few pixels to the right, but the content would stay in its original position, giving the appearance that the content had all shifted left relative to its container. This would be especially problematic on elements with no or small amounts of padding. I was able to hack my way around the problem in IE8 by using X-UA-Compatible, but I'd rather avoid this solution if at all possible. I don't have access to IE9 for testing but my understanding hacks like PIE aren't necessary and it would be wasteful to force a compatibility mode in a browser that doesn't need it. I have worse issues in IE6, with the PIE layout breaking down completely on a list that is set up to use display:inline; zoom:1; list items (to simulate inline-block, which works in IE8 and the other browsers). Here the borders of the list items get rendered in completely the wrong place. So ideally, I'd like to have PIE work properly in IE6, and in IE8 without having to resort to compatibility mode. As far as IE6 goes, a graceful fallback where PIE is just not applied will do. IE7 is the only browser where the page displays as intended. I can't provide an example page just at the moment unfortunately, I can add one later though. Follow up: Here are some screen grabs made with IE Tester. I'm hoping they will make things a little more clear for everybody. As you can see, IE7 is fine. However, in IE8, the containers are offset to the left relative to their content, and in IE6 the list elements (with the rounded 1 pixel border) are a complete mess! Full size versions for IE8, IE7 and IE6 are also available

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  • Creating a web application that can be extended by plugins/modules

    - by Adam Pope
    I'm currently involved with developing a C# CMS-like web application which will be used to standardise our development of websites. From the outset, the idea has been to keep the core as simple as possible to avoid the complexity and menu/option overload that blights many CMS systems. This simple core is now complete and working very well. We envisisaged that the system would be able to accept plugins or modules which would extend the core functionality to suit a given projects needs. These would also be re-usable across projects. For example, a basic catalogue and shopping basket might be needed. All the code for such extensions should be in seperate assemblies. They should be able to provide their own admin interfaces and front-end code from this library. The system should search for available plugins and give the admin user the option to enable/disable the feature. (This is all very much like WordPress plugins) It is crucial that we attack this problem in the correct way, so I'm trying to perform as much due dilligence as possible before jumping in. I am aware of the Plugin Pattern (http://msdn.microsoft.com/en-us/library/ms972962.aspx) and have read some articles on it's use. It seems reasonable but I'm not convinced it's necessarily the correct/best technique for this situation. It seems more suited to processing applications (image/audio manipulation, maths etc). Are there any other options for achieving this kind of UI extensibility functionality? Or is the plugin pattern the way to go? I'd also be interested if anybody has links to articles that explain using the plugin pattern for this purpose?

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  • Sync version of the project with Java

    - by Alexadar
    I have a problem, I need to sync version of the project. Changes are performed on main project that resides on central Coldfusion server. There are about 30 remote Coldfusion servers, that has to sync with latest version on central server. New synch application will to be done in Java! I have a direct link to each remote location. Mostly Windows OS and Windows tools are used. My idea: The synchronization is performed at the level of synchronization of folders. I would like to avoid the use of SVN and similar tools. My idea is to carry out comparison of folders on the local server (comparison is performed between the old and new versions),with NO communication with remote servers, make the difference between the versions and the same is sent to the remote machines. We will install Tomcat on every remote server. "Sync application" deployed on Tomcat will take care about differences. Remote server will return me an answer, about the success of the sync. Any kind of suggestion or completely new approach on this topic is more than welcome. Thanks Best regards

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  • C# & SQL Server Authentication

    - by Peter
    Hello, I'm currently developing a C# app with an SQL Server DB back-end. I'm approaching the point of deployment and hitting a problem. The applicaiton will be deployed within an active directory network. As far as SQL authentication goes, I understand that I have 2 options - Windows Authenticaiton or Server Authenticaiton. If I use Server Authentication, I'm concerned that the username and password for the account will be stored in plain text in the app.config file, and therefore leave the database vulnerable. Using Windows Authenticaiton will avoid this issue, however it would mean giving every member of staff within our organisation read/write access to the database in order to run the app correctly. Whilst this is ok, it also means that they can easily connect to the database themselves via other means and directly alter the data outside of the app. I'm guessing there is someting really obvious I'm missing here, but I've been googling all evening to no avail. Any advice/guidance would be much appreciated! Peter Addition - my project is Windows Form based not ASP.NET - is encrypting the app.config file still the right answer? If it is, does anyone have any examples that are not ASP.NET based?

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  • Common "truisms" needing correction the most

    - by Charles Bretana
    In addition to "I never met a man I didn't like", Will Rogers had another great little ditty I've always remembered. It went: "It's not what you don't know that'll hurt you, it's what you do know that ain't so." We all know or subscribe to many IT "truisms" that mostly have a strong basis in fact, in something in our professional careers, something we learned from others, lessons learned the hard way by ourselves, or by others who came before us. Unfortuntely, as these truisms spread throughout the community, the details—why they came about and the caveats that affect when they apply—tend to not spread along with them. We all have a tendency to look for, and latch on to, small "rules" or principles that we can use to avoid doing a complete exhaustive analysis for every decision. But even though they are correct much of the time, when we sometimes misapply them, we pay a penalty that could be avoided by understooding the details behind them. For example, when user-defined functions were first introduced in SQL Server it became "common knowledge" within a year or so that they had extremely bad performance (because it required a re-compilation for each use) and should be avoided. This "trusim" still increases many database developers' aversion to using UDFs, even though Microsoft's introduction of InLine UDFs, which do not suffer from this issue at all, mitigates this issue substantially. In recent years I have run into numerous DBAs who still believe you should "never" use UDFs, because of this. What other common not-so-"trusims" do you know, which many developers believe, that are not quite as universally true as is commonly understood, and which the developer community would benefit from being better educated about? Please include why it was "true" to start off with, and under what circumstances it's not true. Limit responses to issues that are technical, where the "common" application of a "rule or principle" is in fact correct most of the time, or was correct back when it was first elucidated, but—in the edge cases, or because of not understanding the principle thoroughly, because technology has changed since it first spread, or applying the rule today without understanding the details behind the rule—can easily backfire or cause the opposite of the intended effect.

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  • What's a good way to parameterize "static" content (e.g. CSS) in a Tomcat webapp?

    - by Steven Huwig
    Some of our CSS files contain parameters that can vary based on the deployment location (dev, QA, prod). For example: background: url(#DOJO_PATH#/dijit/themes...) to avoid hardcoding a path to a particular CDN or locally-hosted Dojo installation. These values are textually substituted with the real values by a deployment script, when it copies the contents of the webapp into the Tomcat webapps directory. That way the same deployment archive file (WAR + TAR file containing other configuration) can be deployed to dev, QA, and prod, with the varying parameters provided by environment-specific configuration files. However, I'd like to make the contents of the WAR (including the templatized CSS files) independent of this in-house deployment script. Since we don't really have control over the deployment script, all I can think to do is configure Tomcat with #DOJO_PATH# etc. as environment variables in the application's context.xml, and use Tomcat to insert those parameters into the CSS at runtime. I could make the CSS files into generated JSPs, but it seems a little ugly to me. Moreover, the substitution only needs to be done once per application deployment, so repeatedly dynamically generating the stylesheets using JSP will be rather wasteful. Does anyone have any alternative ideas or tools to use for this? We're committed to Tomcat and to substituting these parameters at deployment or at runtime (that is, not at build time).

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  • client-side data storage and retrieval with html and javascript

    - by pedalpete
    I'm building what I am hoping to be a fairly simple, quick and dirty demo app. So far, I've managed to build a bunch of components using only html and javascript. I know that eventually I'll hook-up a db, but at this point I'm just trying to show off some functionality. In the page, a user can select a bunch of other users (like friends). Then they go to a separate html page and there is some sorting info based on the selected users. So my first attempt was to put the selected users object into a cookie, and retrieve the cookie on the second page. Unfortunately, if the user changed their selection, the cookie wasn't getting updated, and my searches on StackOverflow seemed to say that deleting and updating cookies is unreliable. I tried function updateCookie(updatedUserList){ jQuery.cookie('userList',null); jQuery.cookie('userList',updatedUserList); } but though it set the cookie to null, it wouldn't update it on the second value. So I decided to put the selected users object into a form. Unfortunately, it looks like I can't retrieve the contents from the form on the client-side, only on the server-side. Is there another way to do this? I've worked in PHP and Rails, but I'm trying to do this quickly and simply before building it out into something larger and am trying to avoid any server-side processing for now, which I have managed to do up to this point.

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  • Mysql slow query: INNER JOIN + ORDER BY causes filesort

    - by Alexander
    Hello! I'm trying to optimize this query: SELECT `posts`.* FROM `posts` INNER JOIN `posts_tags` ON `posts`.id = `posts_tags`.post_id WHERE (((`posts_tags`.tag_id = 1))) ORDER BY posts.created_at DESC; The size of tables is 38k rows, and 31k and mysql uses "filesort" so it gets pretty slow. I tried to use different indexes, no luck. CREATE TABLE `posts` ( `id` int(11) NOT NULL auto_increment, `created_at` datetime default NULL, PRIMARY KEY (`id`), KEY `index_posts_on_created_at` (`created_at`), KEY `for_tags` (`trashed`,`published`,`clan_private`,`created_at`) ) ENGINE=InnoDB AUTO_INCREMENT=44390 DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci CREATE TABLE `posts_tags` ( `id` int(11) NOT NULL auto_increment, `post_id` int(11) default NULL, `tag_id` int(11) default NULL, `created_at` datetime default NULL, `updated_at` datetime default NULL, PRIMARY KEY (`id`), KEY `index_posts_tags_on_post_id_and_tag_id` (`post_id`,`tag_id`) ) ENGINE=InnoDB AUTO_INCREMENT=63175 DEFAULT CHARSET=utf8 +----+-------------+------------+--------+--------------------------+--------------------------+---------+---------------------+-------+-----------------------------------------------------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+------------+--------+--------------------------+--------------------------+---------+---------------------+-------+-----------------------------------------------------------+ | 1 | SIMPLE | posts_tags | index | index_post_id_and_tag_id | index_post_id_and_tag_id | 10 | NULL | 24159 | Using where; Using index; Using temporary; Using filesort | | 1 | SIMPLE | posts | eq_ref | PRIMARY | PRIMARY | 4 | .posts_tags.post_id | 1 | | +----+-------------+------------+--------+--------------------------+--------------------------+---------+---------------------+-------+-----------------------------------------------------------+ 2 rows in set (0.00 sec) What kind of index I need to define to avoid mysql using filesort? Is it possible when order field is not in where clause?

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  • is concatenating the only way to 'import' one JS lib from another?

    - by Nikita
    Disclaimer: JS novice I have a JS widget that depends on JQuery. The widget's going to be embedded in a 3rd party site but I figure out how to avoid declaring dependency on jquery on the widget-hosting page: 3rd party's page: <head> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.js"></script> <script type="text/javascript" src="http://mydomain/mywidget.js"></script> </head> mywidget.js jQuery(document).ready(function() { //do stuff }); I'd rather not include jquery.js in the 3d party page but express the dependency inside mywidget.js (so i can change this dependency or add/remove others w/o having to update the widget-hosting page) I tried adding: var script = document.createElement('script'); script.src = 'http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.js'; script.type = 'text/javascript'; document.getElementsByTagName('head')[0].appendChild(script); to the top of mywidget.js but that didn't work - jquery.js did load on page load but "jQuery" was not recognized. What did work was concatenating jquery.js and mywidget.js into a single .js file. But that seems kind of lame - is there no equivalent to? import com.jquery.*; thanks!

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  • @selector and return value

    - by user320926
    The idea it's very easy, i have an http download class, this class must support the http authentication but it's basically a background thread so i would like to avoid to prompt directly to the screen, i would like to use a delegate method to require from outside of the class, like a viewController. But i don't know if is possible or if i have to use a different syntax. This class use this delegate protocol: //Updater.h @protocol Updater <NSObject> -(NSDictionary *)authRequired; @optional -(void)statusUpdate:(NSString *)newStatus; -(void)downloadProgress:(int)percentage; @end @interface Updater : NSThread { ... } This is the call to the delegate method: //Updater.m // This check always fails :( if ([self.delegate respondsToSelector:@selector(authRequired:)]) { auth = [delegate authRequired]; } This is the implementation of the delegate method //rootViewController.m -(NSDictionary *)authRequired; { // TODO: some kind of popup or modal view NSMutableDictionary *ret=[[NSMutableDictionary alloc] init]; [ret setObject:@"utente" forKey:@"user"]; [ret setObject:@"password" forKey:@"pass"]; return ret; }

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  • Django: returning a selection of fields from a model based on their values?

    - by AP257
    I am working with some data over which I have little control. I'd like to return ONLY the fields of my model that aren't certain 'uninteresting' values (e.g. '0', 'X' or '-'), and access them individually in the template. My model is like this: class Manors(models.Model): structidx = models.IntegerField(primary_key=True, verbose_name="ID") hills = models.CharField(max_length=100, null=True, blank=True, verbose_name="Number of fields") In my template, I return a QuerySet of Manors, and I'd like to output something like this if the hills field isn't uninteresting: {% for manor in manors %} {% if manor.hills %}<li>Hills blah blah: {{ manor.hills }}</li>{% endif %} {% endfor %} I want to avoid too much logic in the template. Ideally, the manor object would simply not return with the uninteresting fields attached, then I could just do {% if manor.hills %}. I tried writing a model method that returns a dictionary of the interesting values, like this: def get_field_dictionary(self): interesting_fields = {} for field in Manors._meta.fields: if field.value_to_string(self) != "N" and field.value_to_string(self) != "0" and field.value_to_string(self) != "-" and field.value_to_string(self) != "X": interesting_fields[field.name] = field.value_to_string(self) return interesting_fields But I don't know how to access individual values of the dictionary in the template: {% if manor.get_field_dictionary['hills'] %}<li>Hills blah blah: {{ manor.get_field_dictionary['hills'] }}</li>{% endif %} gives a TemplateSyntaxError. Is there a better way to do this?

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  • Command or tool to display list of connections to a Windows file share

    - by BizTalkMama
    Is there a Windows command or tool that can tell me what users or computers are connected to a Windows fileshare? Here's why I'm looking for this: I've run into issues in the past where our deployment team has deployed BizTalk applications to one of our environments using the wrong bindings, leaving us with two receive locations pointing to the same file share (i.e. both dev and test servers point to dev receive location uri). When this occurs, the two environments in question tend to take turns processing the files received (meaning if I am attempting to debug something in one environment and the other environment has picked the file up, it looks as if my test file has disappeared into thin air). We have several different environments, plus individual developer machines, and I'd rather not have to check each individually to find the culprit. I'm looking for a quick way to detect what locations are connected to the share once I notice my test files vanishing. If I can determine the connections that are invalid, I can go directly to the person responsible for that environment and avoid the time it takes to randomly ask around. Or if the connections appear to be correct, I can go directly to troubleshooting where in the process the message gets lost. Any suggestions?

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  • Combining Java hashcodes into a "master" hashcode

    - by Nick Wiggill
    I have a vector class with hashCode() implemented. It wasn't written by me, but uses 2 prime numbers by which to multiply the 2 vector components before XORing them. Here it is: /*class Vector2f*/ ... public int hashCode() { return 997 * ((int)x) ^ 991 * ((int)y); //large primes! } ...As this is from an established Java library, I know that it works just fine. Then I have a Boundary class, which holds 2 vectors, "start" and "end" (representing the endpoints of a line). The values of these 2 vectors are what characterize the boundary. /*class Boundary*/ ... public int hashCode() { return 1013 * (start.hashCode()) ^ 1009 * (end.hashCode()); } Here I have attempted to create a good hashCode() for the unique 2-tuple of vectors (start & end) constituting this boundary. My question: Is this hashCode() implementation going to work? (Note that I have used 2 different prime numbers in the latter hashCode() implementation; I don't know if this is necessary but better to be safe than sorry when trying to avoid common factors, I guess -- since I presume this is why primes are popular for hashing functions.)

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  • Tree-like queues

    - by Rehno Lindeque
    I'm implementing a interpreter-like project for which I need a strange little scheduling queue. Since I'd like to try and avoid wheel-reinvention I was hoping someone could give me references to a similar structure or existing work. I know I can simply instantiate multiple queues as I go along, I'm just looking for some perspective by other people who might have better ideas than me ;) I envision that it might work something like this: The structure is a tree with a single root. You get a kind of "insert_iterator" to the root and then push elements onto it (e.g. a and b in the example below). However, at any point you can also split the iterator into multiple iterators, effectively creating branches. The branches cannot merge into a single queue again, but you can start popping elements from the front of the queue (again, using a kind of "visitor_iterator") until empty branches can be discarded (at your discretion). x -> y -> z a -> b -> { g -> h -> i -> j } f -> b Any ideas? Seems like a relatively simple structure to implement myself using a pool of circular buffers but I'm following the "think first, code later" strategy :) Thanks

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  • Eliminate full table scan due to BETWEEN (and GROUP BY)

    - by Dave Jarvis
    Description According to the explain command, there is a range that is causing a query to perform a full table scan (160k rows). How do I keep the range condition and reduce the scanning? I expect the culprit to be: Y.YEAR BETWEEN 1900 AND 2009 AND Code Here is the code that has the range condition (the STATION_DISTRICT is likely superfluous). SELECT COUNT(1) as MEASUREMENTS, AVG(D.AMOUNT) as AMOUNT, Y.YEAR as YEAR, MAKEDATE(Y.YEAR,1) as AMOUNT_DATE FROM CITY C, STATION S, STATION_DISTRICT SD, YEAR_REF Y FORCE INDEX(YEAR_IDX), MONTH_REF M, DAILY D WHERE -- For a specific city ... -- C.ID = 10663 AND -- Find all the stations within a specific unit radius ... -- 6371.009 * SQRT( POW(RADIANS(C.LATITUDE_DECIMAL - S.LATITUDE_DECIMAL), 2) + (COS(RADIANS(C.LATITUDE_DECIMAL + S.LATITUDE_DECIMAL) / 2) * POW(RADIANS(C.LONGITUDE_DECIMAL - S.LONGITUDE_DECIMAL), 2)) ) <= 50 AND -- Get the station district identification for the matching station. -- S.STATION_DISTRICT_ID = SD.ID AND -- Gather all known years for that station ... -- Y.STATION_DISTRICT_ID = SD.ID AND -- The data before 1900 is shaky; insufficient after 2009. -- Y.YEAR BETWEEN 1900 AND 2009 AND -- Filtered by all known months ... -- M.YEAR_REF_ID = Y.ID AND -- Whittled down by category ... -- M.CATEGORY_ID = '003' AND -- Into the valid daily climate data. -- M.ID = D.MONTH_REF_ID AND D.DAILY_FLAG_ID <> 'M' GROUP BY Y.YEAR Update The SQL is performing a full table scan, which results in MySQL performing a "copy to tmp table", as shown here: +----+-------------+-------+--------+-----------------------------------+--------------+---------+-------------------------------+--------+-------------+ | id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra | +----+-------------+-------+--------+-----------------------------------+--------------+---------+-------------------------------+--------+-------------+ | 1 | SIMPLE | C | const | PRIMARY | PRIMARY | 4 | const | 1 | | | 1 | SIMPLE | Y | range | YEAR_IDX | YEAR_IDX | 4 | NULL | 160422 | Using where | | 1 | SIMPLE | SD | eq_ref | PRIMARY | PRIMARY | 4 | climate.Y.STATION_DISTRICT_ID | 1 | Using index | | 1 | SIMPLE | S | eq_ref | PRIMARY | PRIMARY | 4 | climate.SD.ID | 1 | Using where | | 1 | SIMPLE | M | ref | PRIMARY,YEAR_REF_IDX,CATEGORY_IDX | YEAR_REF_IDX | 8 | climate.Y.ID | 54 | Using where | | 1 | SIMPLE | D | ref | INDEX | INDEX | 8 | climate.M.ID | 11 | Using where | +----+-------------+-------+--------+-----------------------------------+--------------+---------+-------------------------------+--------+-------------+ Related http://dev.mysql.com/doc/refman/5.0/en/how-to-avoid-table-scan.html http://dev.mysql.com/doc/refman/5.0/en/where-optimizations.html http://stackoverflow.com/questions/557425/optimize-sql-that-uses-between-clause Thank you!

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  • How can I use a compound condition in a join in Linq?

    - by Gary McGill
    Let's say I have a Customer table which has a PrimaryContactId field and a SecondaryContactId field. Both of these are foreign keys that reference the Contact table. For any given customer, either one or two contacts may be stored. In other words, PrimaryContactId can never be NULL, but SecondaryContactId can be NULL. If I drop my Customer and Contact tables onto the "Linq to SQL Classes" design surface, the class builder will spot the two FK relationships from the Customer table to the Contact table, and so the generated Customer class will have a Contact field and a Contact1 field (which I can rename to PrimaryContact and SecondaryContact to avoid confusion). Now suppose that I want to get details of all the contacts for a given set of customers. If there was always exactly one contact then I could write something like: from customer in customers join contact in contacts on customer.PrimaryContactId equals contact.id select ... ...which would be translated into something like: SELECT ... FROM Customer INNER JOIN Contact ON Customer.FirstSalesPersonId = Contact.id But, because I want to join on both the contact fields, I want the SQL to look something like: SELECT ... FROM Customer INNER JOIN Contact ON Customer.FirstSalesPersonId = Contact.id OR Customer.SecondSalesPersonId = Contact.id How can I write a Linq expression to do that?

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  • Is the C++ compiler optimizer allowed to break my destructor ability to be called multiple times?

    - by sharptooth
    We once had an interview with a very experienced C++ developer who couldn't answer the following question: is it necessary to call the base class destructor from the derived class destructor in C++? Obviously the answer is no, C++ will call the base class destructor automagically anyway. But what if we attempt to do the call? As I see it the result will depend on whether the base class destructor can be called twice without invoking erroneous behavior. For example in this case: class BaseSafe { public: ~BaseSafe() { } private: int data; }; class DerivedSafe { public: ~DerivedSafe() { BaseSafe::~BaseSafe(); } }; everything will be fine - the BaseSafe destructor can be called twice safely and the program will run allright. But in this case: class BaseUnsafe { public: BaseUnsafe() { buffer = new char[100]; } ~BaseUnsafe () { delete[] buffer; } private: char* buffer; }; class DerivedUnsafe { public: ~DerivedUnsafe () { BaseUnsafe::~BaseUnsafe(); } }; the explicic call will run fine, but then the implicit (automagic) call to the destructor will trigger double-delete and undefined behavior. Looks like it is easy to avoid the UB in the second case. Just set buffer to null pointer after delete[]. But will this help? I mean the destructor is expected to only be run once on a fully constructed object, so the optimizer could decide that setting buffer to null pointer makes no sense and eliminate that code exposing the program to double-delete. Is the compiler allowed to do that?

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  • OCaml delimiters and scopes

    - by Jack
    Hello! I'm learning OCaml and although I have years of experience with imperative programming languages (C, C++, Java) I'm getting some problems with delimiters between declarations or expressions in OCaml syntax. Basically I understood that I have to use ; to concatenate expressions and the value returned by the sequence will be the one of last expression used, so for example if I have exp1; exp2; exp3 it will be considered as an expression that returns the value of exp3. Starting from this I could use let t = something in exp1; exp2; exp3 and it should be ok, right? When am I supposed to use the double semicol ;;? What does it exactly mean? Are there other delimiters that I must use to avoid syntax errors? I'll give you an example: let rec satisfy dtmc state pformula = match (state, pformula) with (state, `Next sformula) -> let s = satisfy_each dtmc sformula and adder a state = let p = 0.; for i = 0 to dtmc.matrix.rows do p <- p +. get dtmc.matrix i state.index done; a +. p in List.fold_left adder 0. s | _ -> [] It gives me syntax error on | but I don't get why.. what am I missing? This is a problem that occurs often and I have to try many different solutions until it suddently works :/ A side question: declaring with let instead that let .. in will define a var binding that lasts whenever after it has been defined? What I basically ask is: what are the delimiters I have to use and when I have to use them. In addition are there differences I should consider while using the interpreter ocaml instead that the compiler ocamlc? Thanks in advance!

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  • Replacing symbol from object file at compile time. For example swapping out main

    - by Anthony Sottile
    Here's the use case: I have a .cpp file which has functions implemented in it. For sake of example say it has the following: [main.cpp] #include <iostream> int foo(int); int foo(int a) { return a * a; } int main() { for (int i = 0; i < 5; i += 1) { std::cout << foo(i) << std::endl; } return 0; } I want to perform some amount of automated testing on the function foo in this file but would need to replace out the main() function to do my testing. Preferably I'd like to have a separate file like this that I could link in over top of that one: [mymain.cpp] #include <iostream> #include <cassert> extern int foo(int); int main() { assert(foo(1) == 1); assert(foo(2) == 4); assert(foo(0) == 0); assert(foo(-2) == 4); return 0; } I'd like (if at all possible) to avoid changing the original .cpp file in order to do this -- though this would be my approach if this is not possible: do a replace for "(\s)main\s*\(" == "\1__oldmain\(" compile as usual. The environment I am targeting is a linux environment with g++.

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