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• (PHP) How do I get XMLReader behave like SimpleXML with Xpath? (Large directory like XML file)

  - by AESM

  So, I've got this huge XML file (10MB and up) that I want to parse and I figured instead of using SimpleXML, I'd better use XMLReader. Since the performance should be way better, right? But since XMLReader doesn't work with XPath... The xml is like this: <root name="bookmarks"> * <dir name="A directory"> <link name="blablabla"> <dir name="Sub directory"> ... </dir> * </dir> * <link name="another link"> </root> With SimpleXML combined with Xpath, I would simple do like: $xml = simplexml_load_file('/xmlFile.xml'); $xml-xpath('/root[@name]/dir[@name="A directory"]/dir[@name="Sub directory"]'); Which is so simple. But how do I do this with just using XMLReader? Ps. I'm converting the resulting node to DOM/SimpleXML to get its inner contents. Like this: $node = $xr-expand(); $dom = new DomDocument(); $n = $dom-importNode($node, true); $dom-appendChild($n); $selectedRoot = simplexml_import_dom($dom); Is this ok? ... Thanks!

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• MySQL Multiple Table Join

  - by hitman001

  I have a 3 tables that I'm trying to join and get distinct results. CREATE TABLE `car` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `name` varchar(255) NOT NULL DEFAULT '', PRIMARY KEY (`id`) ) ENGINE=InnoDB mysql> select * from car; +----+-------+ | id | name | +----+-------+ | 1 | acura | +----+-------+ CREATE TABLE `tires` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `tire_desc` varchar(255) DEFAULT NULL, `car_id` int(10) unsigned NOT NULL, PRIMARY KEY (`id`), KEY `new_fk_constraint` (`car_id`), CONSTRAINT `new_fk_constraint` FOREIGN KEY (`car_id`) REFERENCES `car` (`id`) ON DELETE CASCADE ON UPDATE CASCADE ) ENGINE=InnoDB mysql> select * from tires; +----+-------------+--------+ | id | tire_desc | car_id | +----+-------------+--------+ | 1 | front_right | 1 | | 2 | front_left | 1 | +----+-------------+--------+ CREATE TABLE `lights` ( `id` int(10) unsigned NOT NULL AUTO_INCREMENT, `lights_desc` varchar(255) NOT NULL, `car_id` int(10) unsigned NOT NULL, PRIMARY KEY (`id`), KEY `new1_fk_constraint` (`car_id`), CONSTRAINT `new1_fk_constraint` FOREIGN KEY (`car_id`) REFERENCES `car` (`id`) ON DELETE CASCADE ON UPDATE CASCADE ) ENGINE=InnoDB mysql> select * from lights; +----+-------------+--------+ | id | lights_desc | car_id | +----+-------------+--------+ | 1 | right_light | 1 | | 2 | left_light | 1 | +----+-------------+--------+ Here is my query. mysql> SELECT name, group_concat(tire_desc), group_concat(lights_desc) FROM car left join tires on car.id = tires.car_id left join lights on car.id = car_id group by car.id; +-------+-----------------------------------------------+-----------------------------------------------+ | name | group_concat(tire_desc) | group_concat(lights_desc) | +-------+-----------------------------------------------+-----------------------------------------------+ | acura | front_right,front_right,front_left,front_left | right_light,left_light,right_light,left_light | +-------+-----------------------------------------------+-----------------------------------------------+ I get duplicate entires and this is what I would like to get. +-------+-----------------------------------------------+--------------------------------+ | name | group_concat(tire_desc) | group_concat(lights_desc) | +-------+-----------------------------------------------+--------------------------------+ | acura | front_right,front_left | right_light,left_light | +-------+-----------------------------------------------+--------------------------------+ I cannot use distinct in group_concat because I might have legitimate duplicates which I would like to keep. Is there any way to do this query using joins and not using inner selects like the statement below? SELECT name, (select group_concat(tire_desc) from tires where car.id = tires.car_id), (select group_concat(lights_desc) from lights where car.id = lights.car_id) FROM car Also, if I will use inner selects, will there be any performance issues over joins?

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• What db fits me?

  - by afvasd

  Dear Everyone I am currently using mysql. I am finding that my schema is getting incredibly complicated. I seek to find a new db that will suit my needs: Let's assume I am building a news aggregrator (which collects news from multiple website). I then run algorithms to determine if two news from different sites are actually referring to the same topic. I run this algorithm to cluster news together. The relationship is depicted below: cluster \--news1 \--word1 \--word2 \--news2 \--word3 \--news3 \--word1 \--word3 And then I will apply some magic and determine the importance of each word. Summing all the importance of each word gives me the importance of a news article. Summing the importance of each news article gives me the importance of a cluster. Note that above cluster there are also subgroups( like split by region etc), and categories (like sports, etc) which I have to determine the importance of that in a particular day per se. I have used views in the past to do so, but I realized that views are very slow. So i will normally do an insert into an actual table and index them for better performance. As you can see this leads to multiple tables derived like (cluster, importance), (news, importance), (words, importance) etc which can get pretty messy. Also the "importance" metric will change. It has become increasingly difficult to alter tables, update data (which I am using TRUNCATE TABLE) and then inserting from null. I am currently looking into something schemaless like Mongodb. I do not need distributedness. I would very much want something that is reasonably fast (which can be indexed) and something that is a lot more flexible that traditional RDMBS. Also, I need something that has some kind of ORM because I personally like ORM a lot. I am currently using sqlalchemy Please help!

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• More efficient way to update multiple elements in javascript and/or jquery?

  - by Seiverence

  Say I have 6 divs with ID "#first", ""#second" ... "#sixth". Say if I wanted to execute functions on each of those divs, I would set up an array that contains each of the names of the divs I want to update as an element in the array of strings. ["first", "second", "third"] that I want to update. If I wanted to apply I function, I set up a for loop that iterates through each element in the array and say if I wanted to change the background color to red: function updateAllDivsInTheList() { for(var i = 0; i < array.size; i++) $("#"+array[i]).changeCssFunction(); } } Whenever I create a new div, i would add it to the array. The issue is, if I have a large number of divs that need to get updated, say if I wanted to update 1000 out of 1200 divs, it may be a pain/performance tank to have to sequentially iterate through every single element in the array. Is there some alternative more efficient way of updating multiple divs without having to sequentially iterate through every element in an array, maybe with some other more efficient data structure besides array? Or is what I am doing the most efficient way to do it? If can provide some example, that would be great.

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• How do I grab hold of a pop-up that is opened from a frame?

  - by KLA

  I am testing a website using WatiN. On one of the pages I get a "report" in an Iframe, within this I frame there is a link to download and save the report. But since the only way to get to the link is to use frame.Link(...) the pop-up closes immediately after opening; Code snippet below //Click the create graph button ie.Button(Find.ById("ctl00_ctl00_ContentPlaceHolder1_TopBoxContentPlaceHolder_btnCreateGraph")).Click(); //Lets export the data ie.Div(Find.ById("colorbox")); ie.Div(Find.ById("cboxContent")); ie.Div(Find.ById("cboxLoadedContent")); Thread.Sleep(1000);//Used to cover performance issues Frame frame = ie.Frame(Find.ByName(frameNameRegex)); for (int Count = 0; Count < 10000000; Count++) {double nothing = (Count/12); }//Do nothing I just need a short pause //SelectList waits for a postback which does not occur. try { frame.SelectList(Find.ById("rvReport_ctl01_ctl05_ctl00")).SelectByValue("Excel"); } catch (Exception) { //Do nothing } //Now click export frame.Link(Find.ById("rvReport_ctl01_ctl05_ctl01")).ClickNoWait(); IE ieNewBrowserWindow = IE.AttachTo<IE>(Find.ByUrl(urlRegex)); fileDownloadHandler.WaitUntilFileDownloadDialogIsHandled(150); fileDownloadHandler.WaitUntilDownloadCompleted(200); I have tried using ie instead of frame which is why all those ie.Div's are present. if I use frame the pop-up window opens and closes instantly. If I use ie I get a link not found error. If I click on the link manually, while the test is "trying to find the link" the file will download correctly.

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• Codeigniter xss_clean dilemma

  - by Henson

  I know this question has been asked over and over again, but I still haven't found the perfect answer for my liking, so here it goes again... I've been reading lots and lots polarizing comments about CI's xss_filter. Basically majority says that it's bad. Can someone elaborate how it's bad, or at least give 1 most probable scenario where it can be exploited? I've looked at the security class in CI 2.1 and I think it's pretty good as it doesn't allow malicious strings like document.cookie, document.write, etc. If the site has basically non-html presentation, is it safe to use global xss_filter (or if it's REALLY affecting performance that much, use it on per form post basis) before inserting to database ? I've been reading about pros and cons about whether to escape on input/output with majority says that we should escape on output only. But then again, why allow strings like <a href="javascript:stealCookie()">Click Me</a> to be saved in the database at all? The one thing I don't like is javascript: and such will be converted to [removed]. Can I extend the CI's security core $_never_allowed_str arrays so that the never allowed strings return empty rather than [removed]. The best reasonable wrongdoing example of this I've read is if a user has password of javascript:123 it will be cleaned into [removed]123 which means string like this document.write123 will also pass as the user's password. Then again, what is the odds of that to happen and even if it happens, I can't think of any real harm that can do to the site. Thanks

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• What is the best way to create a running integer id on the AppEngine data storage?

  - by Freed

  For various reasons, I need a unique running integer id for my entities stored on the Google AppEngine. The automatically generated key sort of has this behaviour, but it doesn't start from 1 (or 0) and doesn't guarantee that the generated integer part will come from a continuous sequence. What would be the best way to efficiently implement this on AppEngine? Is there any support from the storage system? To add to the complexity, I might need to do this over entities from different entity groups, meaning I can't just get the highest id right now and save an entity with the next id in a transaction. Might memcache be the way to go..? Edit: I havn't yet implemented this, but to clarify on the memcache idea. I know memcache is unreliable, but in practice it probably won't lose data "too often" to hurt performance. Basically, I would have a memcache entry for the last used id, update it (somehow atomically) whenever I create a new entity and use that id. In the case of memcache not having a value for this entry, I'd get the highest id so far by doing a query on my entities sorted by the id and update memcache (unless someone else had already done so). The only problem I can see with this right now would be atomicity of the operation as a whole if the save of my new entity was also part of a transaction. Thoughts..?

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• Elegent methods for caching search results from RESTful service?

  - by Paul

  I have a RESTful web service which I access from the browser using JavaScript. As an example, say that this web service returns a list of all the Message resources assigned to me when I send a GET request to /messages/me. For performance reasons, I'd like to cache this response so that I don't have to re-fetch it every time I visit my Manage Messages web page. The cached response would expire after 5 minutes. If a Message resource is created "behind my back", say by the system admin, it's possible that I won't know about it for up to 5 minutes, until the cached search response expires and is re-fetched. This is acceptable, because it creates no confusion for me. However if I create a new Message resource which I know should be part of the search response, it becomes confusing when it doesn't appear on my Manage Messages page immediately. In general, when I knowingly create/delete/update a resource that invalidates a cached search response, I need that cached response to be expired/flushed immediately. The core problem which I can't figure out: I see no simple way of connecting the task of creating/deleting/updating a resource with the task of expiring the appropriate cached responses. In this example it seems simple, I could manually expire the cached search response whenever I create/delete/update a(ny) Message resource. But in a more complex system, keeping track of which search responses to expire under what circumstances will get clumsy quickly. If someone could suggest a simple solution or some clarifying thoughts, I'd appreciate it.

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• MySql: Is it reasonable to use 'view' or I would better denormalize my DB?

  - by Budda

  There is 'team_sector' table with following fields: Id, team_id, sect_id, size, level It contains few records for each 'team' entity (referenced with 'team_id' field). Each record represent sector of team's stadium (totally 8 sectors). Now it is necessary to implement few searches: by overall stadium size (SUM(size)); the best quality (SUM(level)/COUNT(*)). I could create query something like this: SELECT TS.team_id, SUM(TS.size) as OverallSize, SUM(TS.Level)/COUNT(TS.Id) AS QualityLevel FROM team_sector GROUP BY team_id ORDER BY OverallSize DESC / ORDER BY QualityLevel DESC But my concern here is that calculation for each team will be done each time on query performed. It is not too big overhead (at least now), but I would like to avoid performance issues later. I see 2 options here. The 1st one is to create 2 additional fields in 'team' table (for example) and store there OverallSize and QualityLevel fields. If information if 'sector' table is changed - update those table too (probably would be good to do that with triggers, as sector table doesn't change too often). The 2nd option is to create a view that will provide required data. The 2nd option seems much easier for me, but I don't have a lot of experience/knowledge of work with views. Q1: What is the best option from your perspective here and why? Probably you could suggest other options? Q2: Can I create view in such way that it will do calculations rarely (at least once per day)? If yes - how? Q3: Is it reasonable to use triggers for such purpose (1st option). P.S. MySql 5.1 is used, overall number of teams is around 1-2 thousand, overall number of records in sector table - overall 6-8 thousand. I understand, those numbers are pretty small, but I would like to implement the best practice here.

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• Common Properties: Consolidating Loan, Purchase, Inventory and Sale tables into one Transaction tabl

  - by Frank Computer

  Pawnshop Application: I have separate tables for Loan, Purchase, Inventory & Sales transactions. Each tables rows are joined to their respective customer rows by: customer.pk [serial] = loan.fk [integer]; = purchase.fk [integer]; = inventory.fk [integer]; = sale.fk [integer]; Since there are so many common properties within the four tables, I consolidated the four tables into one table called "transaction", where a column: transaction.trx_type char(1) {L=Loan, P=Purchase, I=Inventory, S=Sale} Scenario: A customer initially pawns merchandise, makes a couple of interest payments, then decides he wants to sell the merchandise to the pawnshop, who then places merchandise in Inventory and eventually sells it to another customer. I designed a generic transaction table where for example: transaction.main_amount DECIMAL(7,2) in a loan transaction holds the pawn amount, in a purchase holds the purchase price, in inventory and sale holds sale price. This is clearly a denormalized design, but has made programming alot easier and improved performance. Any type of transaction can now be performed from within one screen, without the need to change to different tables.

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• dm_exec_query_stats returning stale data?

  - by VoiceOfUnreason

  I've been testing my app on a SQL Server 2005 database, and am trying to establish a preliminary picture of the query performance using sys.dm_exec_query_stats. Problem: there's a particular query that I'm interested in, because total_elapsed_time and last_elapsed_time are both large numbers. When I tickle my app to invoke that query (this runs successfully), then refresh my view of the stats, I find that 1) execution_count has incremented (expected) 2) last_execution_time has updated to now (expected) 3) last_elapsed_time is still a large value (not expected - I anticipated a new value) 4) total_elapsed_time is unchanged (contradiction?) If last_elapsed_time refers to the execution that happened @ last_execution_time, then the total_elapsed_time should have increased? This documentation: http://msdn.microsoft.com/en-us/library/ms189741(SQL.90).aspx tells me that last_execution_time is the last time the plan was executed, and last_elapsed_time comes from the "most recently executed plan", but doesn't tell me why those might be different. The query itself is uncomplicated (SELECT/WHERE/ORDER BY - parameters appearing in the where clause, but no clever operations), the table has maybe 25 rows in it right now. Questions: 1) What's the real relationship between execution_count, last_execution_time, and last_elapsed_time? 2) Where is the documentation of this relationship (manual, third party book, blog, bug ticket, stone tablets...) ?

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• How to optimize this MYSQL table?

  - by Lost_in_code

  This is for an upcoming project. I have two tables - first one keeps tracks of photos, and the second one keeps track of the photo's rank Photos: +-------+-----------+------------------+ | id | photo | current_rank | +-------+-----------+------------------+ | 1 | apple | 5 | | 2 | orange | 9 | +-------+-----------+------------------+ The photo rank keeps changing on a regular basis and this is the table that tracks it: Ranks: +-------+-----------+----------+-------------+ | id | photo_id | ranks | timestamp | +-------+-----------+----------+-------------+ | 1 | 1 | 8 | * | | 2 | 2 | 2 | * | | 3 | 1 | 3 | * | | 4 | 1 | 7 | * | | 5 | 1 | 5 | * | | 6 | 2 | 9 | * | +-------+-----------+----------+-------------+ * = current timestamp Every rank is tracked for reporting/analysis purpose. I talked to someone who has experience in this field and he told me that storing ranks like above is the way to go. But I'm not so sure yet. The problem here is data redundancy. There are going to be tens of thousands of photos. The photo rank changes on a hourly basis (many time within minutes) for recent photos but less frequently for older photos. At this rate the table will have millions of records within months. And since I do not have experience in working with large databases, this makes me a little nervous. I thought of this: Ranks: +-------+-----------+--------------------+ | id | photo_id | ranks | +-------+-----------+--------------------+ | 1 | 1 | 8:*,3:*,7:*,5:* | | 2 | 2 | 2:*,9:* | +-------+-----------+--------------------+ * = current timestamp That means some extra code in PHP to split the rank/time (and sorting) but that looks OK to me. Is this a correct way to optimize the table for performance? What would you recommend? Any suggestions would be great.

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• Which way of declaring a variable is fastest?

  - by ADB

  For a variable used in a function that is called very often and for implementation in J2ME on a blackberry (if that changed something, can you explain)? class X { int i; public void someFunc(int j) { i = 0; while( i < j ){ [...] i++; } } } or class X { static int i; public void someFunc(int j) { i = 0; while( i < j ){ [...] i++; } } } or class X { public void someFunc(int j) { int i = 0; while( i < j ){ [...] i++; } } } I know there is a difference how a static versus non-static class variable is accessed, but I don't know it would affect the speed. I also remember reading somewhere that in-function variables may be accessed faster, but I don't know why and where I read that. Background on the question: some painting function in games are called excessively often and even small difference in access time can affect the overall performance when a variable is used in a largish loop.

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• Rendering ListBox takes too long on Windows Phone

  - by Bhawk1990

  I am working on a Windows Phone 7 Application using Local SQLite Database and I'm having an issue with the rendering time of pages that use DataBinding. Currently it takes 60-70ms to retrieve the data from the database. Then it takes about 3100ms to render the data retrieved using a ListBox with DataBinding. Here you can see the DataTemplate of the ListBox: <DataTemplate x:Key="ListBoxItemTemplate"> <Grid> <Grid.ColumnDefinitions> <ColumnDefinition Width="68" /> <ColumnDefinition /> </Grid.ColumnDefinitions> <TextBlock x:Name="TimeColumn" Text="{Binding TimeSpan}" Grid.Column="0" Grid.Row="0" Foreground="White" HorizontalAlignment="Center" VerticalAlignment="Center" /> <TextBlock Text="{Binding Stop.StopName}" Grid.Column="1" Grid.Row="0" Margin="15,0,0,0" TextWrapping="NoWrap" Foreground="Black" HorizontalAlignment="Left" VerticalAlignment="Center" /> </Grid> </DataTemplate> Comment: I have tried it using Canvas instead of Grid too, same result. Then, the database loads data into a CSList (using ViciCoolStorage) and that gets Binded to the ListBox: StationList.ItemsSource = App.RouteViewModel.RouteStops; Comment: I have tried to add the elements of the CSList to an ObservableCollection and bind that to the interface but didn't seem to change anything. Question: Am I doing something wrong that results in a huge load time - even if just loading 10 elements -, or this is normal? Do you have any recommendations to get a better performance with DataBinding? Thank you for your answers in advance!

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• Recomendations for Creating a Picture Slide Show with Super-Smooth Transitions (For Live Presentaito

  - by Nick

  Hi everyone, I'm doing a theatrical performance, and I need a program that can read images from a folder and display them full screen on one of the computer's VGA outputs, in a predetermined order. All it needs to do is start with the first image, and when a key is pressed (space bar, right arrow), smoothly cross-fade to the next image. Sounds just like power-point right? The only reason why I can use power-point/open-office is because the "fade smoothly" transition isn't smooth enough, or configurable enough. It tends to be fast and choppy, where I would like to see a perfectly smooth fade over, say, 30 seconds. So the question is what is the best (cheap and fast) way to accomplish this? Is there a program that already does this well (for cheap or free)? OR should I try to hack at open-office's transition code? Or would it be easier to create this from scratch? Are there frameworks that might make it easier? I have web programming experience (php), but not desktop or real-time rendering. Any suggestions are appreciated!

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• Questions about shifting from mysql to PDO

  - by Scarface

  Hey guys I have recently decided to switch all my current plain mysql queries performed with php mysql_query to PDO style queries to improve performance, portability and security. I just have some quick questions for any experts in this database interaction tool Will it prevent injection if all statements are prepared? (I noticed on php.net it wrote 'however, if other portions of the query are being built up with unescaped input, SQL injection is still possible' I was not exactly sure what this meant). Does this just mean that if all variables are run through a prepare function it is safe, and if some are directly inserted then it is not? Currently I have a connection at the top of my page and queries performed during the rest of the page. I took a look at PDO in more detail and noticed that there is a try and catch procedure for every query involving a connection and the closing of that connection. Is there a straightforward way to connecting and then reusing that connection without having to put everything in a try or constantly repeat the procedure by connecting, querying and closing? Can anyone briefly explain in layman's terms what purpose a set_exception_handler serves? I appreciate any advice from any more experienced individuals.

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• What guarantees are there on the run-time complexity (Big-O) of LINQ methods?

  - by tzaman

  I've recently started using LINQ quite a bit, and I haven't really seen any mention of run-time complexity for any of the LINQ methods. Obviously, there are many factors at play here, so let's restrict the discussion to the plain IEnumerable LINQ-to-Objects provider. Further, let's assume that any Func passed in as a selector / mutator / etc. is a cheap O(1) operation. It seems obvious that all the single-pass operations (Select, Where, Count, Take/Skip, Any/All, etc.) will be O(n), since they only need to walk the sequence once; although even this is subject to laziness. Things are murkier for the more complex operations; the set-like operators (Union, Distinct, Except, etc.) work using GetHashCode by default (afaik), so it seems reasonable to assume they're using a hash-table internally, making these operations O(n) as well, in general. What about the versions that use an IEqualityComparer? OrderBy would need a sort, so most likely we're looking at O(n log n). What if it's already sorted? How about if I say OrderBy().ThenBy() and provide the same key to both? I could see GroupBy (and Join) using either sorting, or hashing. Which is it? Contains would be O(n) on a List, but O(1) on a HashSet - does LINQ check the underlying container to see if it can speed things up? And the real question - so far, I've been taking it on faith that the operations are performant. However, can I bank on that? STL containers, for example, clearly specify the complexity of every operation. Are there any similar guarantees on LINQ performance in the .NET library specification?

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• for loop vs std::for_each with lambda

  - by Andrey

  Let's consider a template function written in C++11 which iterates over a container. Please exclude from consideration the range loop syntax because it is not yet supported by the compiler I'm working with. template <typename Container> void DoSomething(const Container& i_container) { // Option #1 for (auto it = std::begin(i_container); it != std::end(i_container); ++it) { // do something with *it } // Option #2 std::for_each(std::begin(i_container), std::end(i_container), [] (typename Container::const_reference element) { // do something with element }); } What are pros/cons of for loop vs std::for_each in terms of: a) performance? (I don't expect any difference) b) readability and maintainability? Here I see many disadvantages of for_each. It wouldn't accept a c-style array while the loop would. The declaration of the lambda formal parameter is so verbose, not possible to use auto there. It is not possible to break out of for_each. In pre- C++11 days arguments against for were a need of specifying the type for the iterator (doesn't hold any more) and an easy possibility of mistyping the loop condition (I've never done such mistake in 10 years). As a conclusion, my thoughts about for_each contradict the common opinion. What am I missing here?

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• List of running minimum values

  - by scarle88

  Given a sorted list of: new []{1, 2, -1, 3, -2, 1, 1, 2, -1, -3} I want to be able to iterate over the list and at each element return the smallest value iterated so far. So given the list above the resultant list would look like: 1 1 -1 -1 -2 -2 -2 -2 -2 -3 My rough draft code looks like: var items = new []{1, 2, -1, 3, -2, 1, 1, 2, -1, -3}; var min = items.First(); var drawdown = items.Select(i => { if(i < min) { min = i; return i; } else { return min; } }); foreach(var i in drawdown) { Console.WriteLine(i); } But this is not very elegant. Is there an easier to read (linq?) way of doing this? I looked into Aggregate but it seemed to be the wrong tool. Ultimately the list of items will be very long, in the many thousands. So good performance will be an issue to.

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• A generic Re-usable C# Property Parser utility

  - by Shyam K Pananghat

  This is about a utility i have happened to write which can parse through the properties of a data contracts at runtime using reflection. The input required is a look like XPath string. since this is using reflection, you dont have to add the reference to any of your data contracts thus making pure generic and re- usable.. you can read about this and get the full c# sourcecode here. Property-Parser-A-C-utility-to-retrieve-values-from-any-Net-Data-contracts-at-runtime Now about the doubts which i have about this utility. i am using this utility enormously i many places of my code I am using Regex repetedly inside a recursion method. does this affect the memmory usage or GC collection badly ?do i have to dispose this manually. if yes how ?. The statements like obj.GetType().GetProperty() and obj.GetType().GetField() returns .net "object" which makes difficult or imposible to introduce generics here. Does this cause to have any overheads like boxing ? on an overall, please suggest to make this utility performance efficient and more light weight on memmory

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• Dynamic Image Caching with Java

  - by zteater

  I have a servlet with an API that delivers images from GET requests. The servlet creates a data file of CAD commands based on the parameters of the GET request. This data file is then delivered to an image parser, which creates an image on the file system. The servlet reads the image and returns the bytes on the response. All of the IO and the calling of the image parser program can be very taxing and images of around 80kb are rendering in 3-4000ms on a local system. There are roughly 20 parameters that make up the GET request. Each correlates to a different portion of the image. So, the combinations of possible images is extremely large. To alleviate the loading time, I plan to store BLOBs of rendered images in a database. If a GET request matches one previously executed, I will pull from cache. Else, I will render a new one. This does not fix "first-time" run, but will help "n+1 runs". Any other ideas on how I can improve performance?

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• List of values as keys for a Map

  - by thr

  I have lists of variable length where each item can be one of four unique, that I need to use as keys for another object in a map. Assume that each value can be either 0, 1, 2 or 3 (it's not integer in my real code, but a lot easier to explain this way) so a few examples of key lists could be: [1, 0, 2, 3] [3, 2, 1] [1, 0, 0, 1, 1, 3] [2, 3, 1, 1, 2] [1, 2] So, to re-iterate: each item in the list can be either 0, 1, 2 or 3 and there can be any number of items in a list. My first approach was to try to hash the contents of the array, using the built in GetHashCode() in .NET to combine the hash of each element. But since this would return an int I would have to deal with collisions manually (two equal int values are identical to a Dictionary). So my second approach was to use a quad tree, breaking down each item in the list into a Node that has four pointers (one for each possible value) to the next four possible values (with the root node representing [], an empty list), inserting [1, 0, 2] => Foo, [1, 3] => Bar and [1, 0] => Baz into this tree would look like this: Grey nodes nodes being unused pointers/nodes. Though I worry about the performance of this setup, but there will be no need to deal with hash collisions and the tree won't become to deep (there will mostly be lists with 2-6 items stored, rarely over 6). Is there some other magic way to store items with lists of values as keys that I have missed?

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• JS best practice for member functions

  - by MickMalone1983

  I'm writing a little mobile games library, and I'm not sure the best practice for declaring member functions of instantiated function objects. For instance, I might create a simple object with one property, and a method to print it: function Foo(id){ this.id = id; this.print = function(){ console.log(this.id); }; }; However, a function which does not need access to 'private' members of the function does not need to be declared in the function at all. I could equally have written: function print(){ console.log(this.id); }; function Foo(id){ this.id = id; this.print = print; }; When the function is invoked through an instance of Foo, the instance becomes the context for this, so the output is the same in either case. I'm not entirely sure how memory is allocated with JS, and I can't find anything that I can understand about something this specific, but it seems to me that with the first example all members of Foo, including the print function, are duplicated each time it is instantiated - but with the second, it just gets a pointer to one, pre-declared function, which would save any more memory having to be allocated as more instances of Foo are created. Am I correct, and if I am, is there any memory/performance benefit to doing this?

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• [PHP] Does unsetting array values during iterating save on memory?

  - by saturn_rising

  Hello fellow code warriors, This is a simple programming question, coming from my lack of knowledge of how PHP handles array copying and unsetting during a foreach loop. It's like this, I have an array that comes to me from an outside source formatted in a way I want to change. A simple example would be: $myData = array('Key1' => array('value1', 'value2')); But what I want would be something like: $myData = array([0] => array('MyKey' => array('Key1' => array('value1', 'value2')))); So I take the first $myData and format it like the second $myData. I'm totally fine with my formatting algorithm. My question lies in finding a way to conserve memory since these arrays might get a little unwieldy. So, during my foreach loop I copy the current array value(s) into the new format, then I unset the value I'm working with from the original array. E.g.: $formattedData = array(); foreach ($myData as $key => $val) { // do some formatting here, copy to $reformattedVal $formattedData[] = $reformattedVal; unset($myData[$key]); } Is the call to unset() a good idea here? I.e., does it conserve memory since I have copied the data and no longer need the original value? Or, does PHP automatically garbage collect the data since I don't reference it in any subsequent code? The code runs fine, and so far my datasets have been too negligible in size to test for performance differences. I just don't know if I'm setting myself up for some weird bugs or CPU hits later on. Thanks for any insights. -sR

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• CreationName for SSIS 2008 and adding components programmatically

  If you are building SSIS 2008 packages programmatically and adding data flow components, you will probably need to know the creation name of the component to add. I can never find a handy reference when I need one, hence this rather mundane post. See also CreationName for SSS 2005. We start with a very simple snippet for adding a component: // Add the Data Flow Task package.Executables.Add("STOCK:PipelineTask"); // Get the task host wrapper, and the Data Flow task TaskHost taskHost = package.Executables[0] as TaskHost; MainPipe dataFlowTask = (MainPipe)taskHost.InnerObject; // Add OLE-DB source component - ** This is where we need the creation name ** IDTSComponentMetaData90 componentSource = dataFlowTask.ComponentMetaDataCollection.New(); componentSource.Name = "OLEDBSource"; componentSource.ComponentClassID = "DTSAdapter.OLEDBSource.2"; So as you can see the creation name for a OLE-DB Source is DTSAdapter.OLEDBSource.2. CreationName Reference  ADO NET Destination Microsoft.SqlServer.Dts.Pipeline.ADONETDestination, Microsoft.SqlServer.ADONETDest, Version=10.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91 ADO NET Source Microsoft.SqlServer.Dts.Pipeline.DataReaderSourceAdapter, Microsoft.SqlServer.ADONETSrc, Version=10.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91 Aggregate DTSTransform.Aggregate.2 Audit DTSTransform.Lineage.2 Cache Transform DTSTransform.Cache.1 Character Map DTSTransform.CharacterMap.2 Checksum Konesans.Dts.Pipeline.ChecksumTransform.ChecksumTransform, Konesans.Dts.Pipeline.ChecksumTransform, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b2ab4a111192992b Conditional Split DTSTransform.ConditionalSplit.2 Copy Column DTSTransform.CopyMap.2 Data Conversion DTSTransform.DataConvert.2 Data Mining Model Training MSMDPP.PXPipelineProcessDM.2 Data Mining Query MSMDPP.PXPipelineDMQuery.2 DataReader Destination Microsoft.SqlServer.Dts.Pipeline.DataReaderDestinationAdapter, Microsoft.SqlServer.DataReaderDest, Version=10.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91 Derived Column DTSTransform.DerivedColumn.2 Dimension Processing MSMDPP.PXPipelineProcessDimension.2 Excel Destination DTSAdapter.ExcelDestination.2 Excel Source DTSAdapter.ExcelSource.2 Export Column TxFileExtractor.Extractor.2 Flat File Destination DTSAdapter.FlatFileDestination.2 Flat File Source DTSAdapter.FlatFileSource.2 Fuzzy Grouping DTSTransform.GroupDups.2 Fuzzy Lookup DTSTransform.BestMatch.2 Import Column TxFileInserter.Inserter.2 Lookup DTSTransform.Lookup.2 Merge DTSTransform.Merge.2 Merge Join DTSTransform.MergeJoin.2 Multicast DTSTransform.Multicast.2 OLE DB Command DTSTransform.OLEDBCommand.2 OLE DB Destination DTSAdapter.OLEDBDestination.2 OLE DB Source DTSAdapter.OLEDBSource.2 Partition Processing MSMDPP.PXPipelineProcessPartition.2 Percentage Sampling DTSTransform.PctSampling.2 Performance Counters Source DataCollectorTransform.TxPerfCounters.1 Pivot DTSTransform.Pivot.2 Raw File Destination DTSAdapter.RawDestination.2 Raw File Source DTSAdapter.RawSource.2 Recordset Destination DTSAdapter.RecordsetDestination.2 RegexClean Konesans.Dts.Pipeline.RegexClean.RegexClean, Konesans.Dts.Pipeline.RegexClean, Version=2.0.0.0, Culture=neutral, PublicKeyToken=d1abe77e8a21353e Row Count DTSTransform.RowCount.2 Row Count Plus Konesans.Dts.Pipeline.RowCountPlusTransform.RowCountPlusTransform, Konesans.Dts.Pipeline.RowCountPlusTransform, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b2ab4a111192992b Row Number Konesans.Dts.Pipeline.RowNumberTransform.RowNumberTransform, Konesans.Dts.Pipeline.RowNumberTransform, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b2ab4a111192992b Row Sampling DTSTransform.RowSampling.2 Script Component Microsoft.SqlServer.Dts.Pipeline.ScriptComponentHost, Microsoft.SqlServer.TxScript, Version=10.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91 Slowly Changing Dimension DTSTransform.SCD.2 Sort DTSTransform.Sort.2 SQL Server Compact Destination Microsoft.SqlServer.Dts.Pipeline.SqlCEDestinationAdapter, Microsoft.SqlServer.SqlCEDest, Version=10.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91 SQL Server Destination DTSAdapter.SQLServerDestination.2 Term Extraction DTSTransform.TermExtraction.2 Term Lookup DTSTransform.TermLookup.2 Trash Destination Konesans.Dts.Pipeline.TrashDestination.Trash, Konesans.Dts.Pipeline.TrashDestination, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b8351fe7752642cc TxTopQueries DataCollectorTransform.TxTopQueries.1 Union All DTSTransform.UnionAll.2 Unpivot DTSTransform.UnPivot.2 XML Source Microsoft.SqlServer.Dts.Pipeline.XmlSourceAdapter, Microsoft.SqlServer.XmlSrc, Version=10.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91 Here is a simple console program that can be used to enumerate the pipeline components installed on your machine, and dumps out a list of all components like that above. You will need to add a reference to the Microsoft.SQLServer.ManagedDTS assembly. using System; using System.Diagnostics; using Microsoft.SqlServer.Dts.Runtime; public class Program { static void Main(string[] args) { Application application = new Application(); PipelineComponentInfos componentInfos = application.PipelineComponentInfos; foreach (PipelineComponentInfo componentInfo in componentInfos) { Debug.WriteLine(componentInfo.Name + "\t" + componentInfo.CreationName); } Console.Read(); } }

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