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• Find if a user is facing a certain Location using Digital Compass by constructing a triangle and usi

  - by Aidan

  Hi Guys, I'm constructing a geolocation based application and I'm trying to figure out a way to make my application realise when a user is facing the direction of the given location (a particular long / lat co-ord). I've done some Googling and checked the SDK but can't really find anything for such a thing. Does anyone know of a way? To clarify Android knows my location, the second location and my orientation. What I want is a way for Android to recognise when my orientation is "facing" the second location (e.g within 90 Degrees or so). We're also assuming that the user is stationary and needs updates every second or so therefore getBearing(); is useless. Alright so we get it has to be math, there appears to be no simple SDK stuff we can use. I did some searching of my own and found Barycentric Co-ords http://www.blackpawn.com/texts/pointinpoly/default.html . So what I'm trying to do now is map the camera's field of view. For Example if the person is facing a certain direction the program should construct a triangle around that field of view, e.g it should make one vertices the phone's position and then go out either side for a set distance making the 2 end points vertices constructing a triangle. If I had this I could then apply Barycentric co-ords to see if the point lay within the newly constructed triangle. Idea's anyone? Example. I could get my current orientation, add 45 to it and go up X distance one side and subtact 45 and go up X distance the other side to find my 2 other points. Though, how would I make android know which way it should go "up" I guess? It would know its baring as this stage so I need it to recognise it's bearing and go out that direction.

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• Custom ADO.NET provider to intercept and modify sql queries.

  - by Faisal

  Our client has an application that stores blobs in database which has now grown enough to impact the performance of SQL Server. To overcome this issue, we are planning to offload all blobs to file system and leave the path of file in a new column in user table. Like if user has a table docs with columns id, name and content (blob); we would ask him to add a new column 'filepath' in this table. Our client is willing to make this change in this database. But when it comes to changing the sql queries to read and write into this table, they are not ready to accep this. Actually, they don't want any change that results in recompilation and deployment. Now we are planning to write a custom ADO.NET provider that will intercept the select queries add a column 'filepath' at the end of the select statement retieve the result set and modify the 'content' column value based on 'filepath' value Is there any use case that you think will certainly fail with this approach? I know this sounds dirty but do we have a better way?

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• Need method to seek next/previous records id without cycling through all records.

  - by dqhendricks

  I am using MySQL and PHP. I have a MySQL blog post result set with id fields, and publish_date fields. I display one blog post per page, and the script knows which blog post to display based on $_GET['id'], which correlates to each blog entry's id field. I would like to reference them by id in the url, because I would like each blog post to have a perminant url. I would like to order the blog posts by publish date (descending). Now, on each page there will be next and previous links, which contain the $_GET['id'] value for the next and previous blog posts. How can I figure out what the id of the next and previous blog posts (determined by it's publish_date order) without cycling through each mysql result row? I can't mysql_data_seek(), because I do not know the row index of the current blog post id. I do not want to store a row index in a GET variable because the urls would no longer be perminant. I obviously cannot store the row index in a SESSION variable because then direct links to specific blog posts would have broken next and previous links. Any suggestions would be greatly appreciated.

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• How to set default view in OpenLayers, WITHOUT restricting bounds?

  - by Jenny

  Based on samples, I can see that you can set a default view in OpenLayers by saying something along the lines of: var bounds = new OpenLayers.Bounds(-125, 25, -65, 50); var map = new OpenLayers.Map('map', {restrictedExtent: bounds }); However, this also (as the name implies), restricts me to be able to ONLY navigate within these bounds. I can zoom out and see things outside of these bounds, but I can't then zoom back onto them, or scroll to them. I've tried not having any restrictedExtent (or making it the entire map), but then I can't get it to focus on the area I want. I tried using: map.setCenter(new OpenLayers.LonLat(0,0), 3); console.log(map.getCenter()); To set the zoom and the center...but it doesn't seem to do ANYTHING, other than set the variable "center" which I can then read from map.getCenter() (if I don't set it, it's null, if I do set it, I can see it...but the map itself stays fully extended and it's center doesn't seem to change at all...) The Map layer I am using is: OpenLayers.Layer.OSM.Mapnik with displayOutsideMaxExtent set to true... I'm really at a loss here. My goal is to have a default region of the world zoomed in to and in view (such as the United States), with the option of viewers being able to go outside the default to view things.

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• Mixing stored procedures and ORM

  - by Jason

  The company I work for develops a large application which is almost entirely based on stored procedures. We use classic ASP and SQL Server and the major part of the business logic is contained inside those stored procedures. For example, (I know, this is bad...) a single stored procedure can be used for different purposes (insert, update, delete, make some calculations, ...). Most of the time, a stored procedure is used for operations on related tables, but this is not always the case. We are planning to move to ASP.NET in a near future. I have read a lot of posts on StackOverflow recommending that I move the business logic outside the database. The thing is, I have tried to convince the people who takes the decisions at our company and there is nothing I can do to change their mind. Since I want to be able to use the advantages of object-oriented programming, I want to map the tables to actual classes. So far, my solution is to use an ORM (Entity Framework 4 or nHibernate) to avoid mapping the objects manually (mostly to retrieve the data) and use some kind of Data Access Layer to call the existing stored procedures (for saving). I want your advice on this. Do you think it is a good solution? Any ideas?

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• problem in variables in jquery

  - by Alvin

  Hi, I don't understand why I'm not getting the message as "username already exits" if type the username which is already in database. If the username in a server, then it is returning the value as "1" otherwise empty, and despite of successfully getting the value from the server based on username is present or not, and assigning the value to variable "x", I'm unable to get message when I pass already exist username. May I know? $(document).ready(pageInit); function pageInit() { $('#1').bind('blur',go); } function go() { var value = $('#1').val(); var x = 0; $.post('just.do',{username:value},function(data){ x = data; } ); if(x) { $('#para').show(); $('#para').html("Username already exits"); return false; } else { $('#para').hide(); return true; } }; EDIT: This is what I'm doing in post request in servlets: String user1 = request.getParameter("username"); if(user != null) { String query = "Select * from users where user_name="+"\""+user+"\""; b = db.doExecuteQuery(stmt,query); if(b) { out.write("1"); } }

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• t-sql help with recursive sort of query

  - by stackoverflowuser

  Hi Based on the following table ID Path --------------------------------------- 1 \\Root 2 \\Root\Node0 3 \\Root\Node0\Node1 4 \\Root\Node0\Node2 5 \\Root\Node3 6 \\Root\Node3\Node4 7 \\Root\Node5 ... N \\Root\Node5\Node6\Node7\Node8\Node9\Node10 so on... There are around 1000 rows in this table. I want to display individual node in seperate columns. Maximum columns to be displayed 5 (i.e. node till 5 level deep). So the output will look as below ID Path Level 0 Level 1 Level 2 Level 3 Level 4 Level 5 ---------------------------------------------------------------------------------------- 1 \\Root Root Null Null Null Null Null 2 \\Root\Node0 Root Node 0 Null Null Null Null 3 \\Root\Node0\Node1 Root Node 0 Node 1 Null Null Null 4 \\Root\Node0\Node2 Root Node 0 Node 2 Null Null Null 5 \\Root\Node3 Root Node 3 Null Null Null Null 6 \\Root\Node3\Node4 Root Node 3 Node 4 Null Null Null 7 \\Root\Node5 Root Node 5 Null Null Null Null ... N (see in above table) Root Node 5 Node 6 Node 7 Node 8 Node 9 The only way i can think of is to open a cursor, loop through each row and perform string split, just fetch the first 5 nodes and then insert into a temp table. Pls. suggest. Thanks

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• Sql Server 2005 Check Constraint not being applied in execution when using variables

  - by DarylS

  Here is some SQL sample code: --Create 2 Sales tables with constraints based on the saledate create table Sales1(SaleDate datetime, Amount money) ALTER TABLE dbo.Sales1 ADD CONSTRAINT CK_Sales1 CHECK (([SaleDate]>='01 May 2010')) GO create table Sales2(SaleDate datetime, Amount money) ALTER TABLE dbo.Sales2 ADD CONSTRAINT CK_Sales2 CHECK (([SaleDate]<'01 May 2010')) GO --Insert some data into Sales1 insert into Sales1 (SaleDate, Amount) values ('02 May 2010', 50) insert into Sales1 (SaleDate, Amount) values ('03 May 2010', 60) GO --Insert some data into Sales2 insert into Sales2 (SaleDate, Amount) values ('30 Mar 2010', 10) insert into Sales2 (SaleDate, Amount) values ('31 Mar 2010', 20) GO --Create a view that combines these 2 tables create VIEW [dbo].[Sales] AS SELECT SaleDate, Amount FROM Sales1 UNION ALL SELECT SaleDate, Amount FROM Sales2 GO --Get the results --Query 1 select * from Sales where SaleDate < '31 Mar 2010' -- if you look at the execution plan this query only looks at Sales2 (Which is good) --Query 2 DECLARE @SaleDate datetime SET @SaleDate = '31 Mar 2010' select * from Sales where SaleDate < @SaleDate -- if you look at the execution plan this query looks at Sales1 and Sales2 (Which is NOT good) Looking at the execution plan you will see that the two queries are differnt. For Query 1 the only table that is accessed is Sales1 (which is good). For Query 2 both tables are accessed (Which is bad). Why are these execution plans different, and how do i get Query 2 to only access the relevant table when variables are used? I have tried to add indexes for the SaleDate column and that does not seem to help.

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• SQL return ORDER BY result as an array

  - by EarthMind

  Is it possible to return groups as an associative array? I'd like to know if a pure SQL solution is possible. Note that I release that I could be making things more complex unnecessarily but this is mainly to give me an idea of the power of SQL. My problem: I have a list of words in the database that should be sorted alphabetically and grouped into separate groups according to the first letter of the word. For example: ape broom coconut banana apple should be returned as array( 'a' => 'ape', 'apple', 'b' => 'banana', 'broom', 'c' => 'coconut' ) so I can easily created sorted lists by first letter (i.e. clicking "A" only shows words starting with a, "B" with b, etc. This should make it easier for me to load everything in one query and make the sorted list JavaScript based, i.e. without having to reload the page (or use AJAX). Side notes: I'm using PostgreSQL but a solution for MySQL would be fine too so I can try to port it to PostgreSQL. Scripting language is PHP.

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• count of last item of the day

  - by frenchie

  I have a query in which one of the fields contains the count of status. The status can change several times a day and the count should be based on the final status of the day. For instance, this is what I have for Status1. CountStatus1 = (from status in MyDataContext.StatusHistories where status.UserID == TheUserID where status.StatusDateTime.Month == TheMonth.Month where status.StatusDateTime.Year == TheMonth.Year where status.NewStatus == 1 // where the LAST STATUS OF THE DAY == 1 select status.StatusID).Count() The problem is that I want to select the last status of the day to be equal to 1, and count those. The status for a day can change from 1 to 4 to 2 to 5 to 3 and then to finally to 1; if I write the query like this, the count will include 2 1's and then the 4,2,5 and 3 will also be counted in CountStatus4, CountStatus3, CountStatus"n". The return data is a monthly report grouped by day, where each day is a row. The structure of the query looks like this: var OutputStatusReport = from w in MyDataContext.WorkHistory where w.UserID == TheUserID where w.WorkDatetime.Month == TheMonth.Month where w.WorkDatetime.Year == TheMonth.Year group w by w.Datetime.Date into daygroups select new MyObjectModel { CountStatus1 = ...., CountStatus2 = ...., CountStatus3 =...... }; So I need the day of the count to match the day of daygroups. I'm struggling to figure this one out and any help is very welcome. Thanks.

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• Am I a dinosaur programmer?

  - by dlb

  I have been a professional programmer for more than 30 years, and have chosen a career path involving hands-on programming. Programming is something that I love, and I take great pride in the fact that I have continued to keep up to date with current technology. Projects on which I have worked include large enterprise projects as well as smaller desktop programs. The problem I am facing is that I do not have any web-based experience other than some web services. Most of the jobs now available have some web component. I have now been out of work for a year and a half, and have been keeping busy by studying technology that will bridge that gap: CSS, Java Script, JQuery, and Ruby on Rails; AJAX is next. Hiring managers give no consideration whatsoever to the studying that I have been doing. I know that I cannot compete at a senior software level, but companies will not hire someone with my experience at a more junior level. Is there any way to break out of this Catch 22?

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• Should I *always* import my file references into the database in drupal?

  - by sprugman

  I have a cck type with an image field, and a unique_id text field. The file name of the image is based on the unique_id. All of the content, including the image itself is being generated automatically via another process, and I'm parsing what that generates into nodes. Rather than creating separate fields for the id and the image, and doing an official import of the image into the files table, I'm tempted to only create the id field and create the file reference in the theme layer. I can think of pros and cons: 1) Theme Layer Approach Pros: makes the import process much less complex don't have to worry about syncing the db with the file system as things change more flexible -- I can move my images around more easily if I want Cons: maybe not as much The Drupal Way™ not as pure -- I'll wind up with more logic on the theme side. 2) Import Approach Pros: import method is required if we ever wanted to make the files private (we won't.) safer? Maybe I'll know if there's a problem with the image at import time, rather than view time. Since I'll be bulk importing, that might make a difference. if I delete a node through the admin interface, drupal might be able to delete the file for me, as well. Con: more complex import and maintenance All else being equal, simpler is always better, so I'm leaning toward #1. Are there any other issues I'm missing? (Since this is an open ended question, I guess I'll make it a community wiki, whatever that means.)

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• Which way to store this data is effective?

  - by Tattat

  I am writing a game, which need a map, and I want to store the map. The first thing I can think of, is using a 2D-array. But the problem is what data should I store in the 2D-array. The player can tap different place to have different reaction. So, I am thinking store a 2D-array with objects, when player click some position, and I find it in the array, and use the object in that array to execute a cmd. But I have a concern that storing lots of object may use lots of memory. So, I am think storing char/int only. But it seems that not enough for me. I want to store the data like that: { Type:1 Color:Green } No matter what color is, if they are all type 1, the have same reactions in logic, but the visual effect is based on the color. So, it is not easy to store using a prue char/int data, unless I make something like this: 1-5 --> all type 1. 1=color green , 2=color red, 3 = color yellow.... ... 6-10 --> all type 2. 2 = color green, 2 = color red ... ... So, do you have any ideas on how to minimize the ram use, but also easy for me to read... ...thx

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• PHP transfer files from server to server in LAN

  - by cheapez

  So, I have 5-6 pages of requirements. I'm trying to build this application in PHP based on the requirements. I want to transfer files from one server to the other server in LAN, and then send a shell command to the other server to find out if the file has been transferred successfully. In php, I can transfer files using FTP, and send shell commands using SSH. Using the methods above, I will need to open connection to the server first, but I don't know the ftp server name, domain name, ip address, or anything like that. I only know the the server ID (I'm not sure what this ID is, but I guess it is like the computer's name). An example of the server ID is: "c23bap234" How do I open a connection with just that server ID? These servers are in the same building, have LAN connection, don't have connection to the outside world. These machines have PHP, Apache, ... installed. If my post doesn't make sense to you, it's because I'm a learner. I hope someone can help me on this. Thanks in advance.

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• ASP.NET DynamicData: Whats happening during an update?

  - by Jens A.

  I am using ASP.NET DynamicData (based on LINQ to SQL) on my site for basic scaffolding. On one table I have added additional properties, that are not stored in the table, but are retrieved from somewhere else. (Profile information for a user account, in this case). They are displayed just fine, but when editing these values and pressing "Update", they are not changed. Here's what the properties look like, the table is the standard aspnet_Users table: public String Address { get { UserProfile profile = UserProfile.GetUserProfile(UserName); return profile.Address; } set { UserProfile profile = UserProfile.GetUserProfile(UserName); profile.Address = value; profile.Save(); } } When I fired up the debugger, I've noticed that for each update the set accessor is called three times. Once with the new value, but on a newly created instance of user, then once with the old value, again on an new instance, and finally with the old value on the existing instance. Wondering a bit, I checked with the properties created by the designer, and they, too, are called three times in (almost) the same fashion. The only difference is, that the last call contains the new value for the property. I am a bit stumped here. Why three times, and why are my new properties behaving differently? I'd be grateful for any help on that matter! =)

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• JavaScript: Replacement for XMLSerializer.seralizeToString()?

  - by NRaf

  I'm developing a website using the Seam framework and the RichFaces AJAX library (these isn't really all that important to the problem at hand - just some background). I seem to have uncovered a bug, however, in RichFaces which, in certain instances, will cause AJAX-based updating to fail in IE8 (see here for more info: http://community.jboss.org/message/585737). The following is the code where the exception is occurring: var anchor = oldnode.parentNode; if(!window.opera && !A4J.AJAX.isWebkitBreakingAmps() && oldnode.outerHTML && !oldnode.tagName.match( /(tbody|thead|tfoot|tr|th|td)/i ) ){ LOG.debug("Replace content of node by outerHTML()"); if (!Sarissa._SARISSA_IS_IE || oldnode.tagName.toLowerCase()!="table") { try { oldnode.innerHTML = ""; } catch(e){ LOG.error("Error to clear node content by innerHTML "+e.message); Sarissa.clearChildNodes(oldnode); } } oldnode.outerHTML = new XMLSerializer().serializeToString(newnode); } The last line (the one with XMLSerializer) is where the exception is occurring in IE. I was wondering if anyone knows of any replacement method / library / etc I could use there (only on IE is fine). Thanks.

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• Javascript code refactoring and assessment

  - by neitony

  I'm using javascript to toggle the display state of some objects based on the time of day. A sample of the code is given below. I was wondering if anyone could give a suggestion as to how I can refactor this code while at the same time improving the logic. switch(tcode) { case 'eur' : eur.setAttribute('style', 'display:block; opacity:0.5'); us.style.display = 'none'; asia.style.display = 'none'; us_inactive.style.display = 'block'; asia_inactive.style.display = 'block'; break; case 'us' : us.style.display = 'block'; eur.style.display = 'none'; asia.style.display = 'none'; eur_inactive.style.display = 'block'; asia_inactive.style.display = 'block'; break; case 'asia' : asia.setAttribute('style', 'display:block; opacity:0.5'); us.style.display = 'none'; eur.style.display = 'none'; eur_inactive.style.display = 'block'; us_inactive.style.display = 'block';

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• Iterative Reduction to Null Matrix

  - by user1459032

  Here's the problem: I'm given a matrix like Input: 1 1 1 1 1 1 1 1 1 At each step, I need to find a "second" matrix of 1's and 0's with no two 1's on the same row or column. Then, I'll subtract the second matrix from the original matrix. I will repeat the process until I get a matrix with all 0's. Furthermore, I need to take the least possible number of steps. I need to print all the "second" matrices in O(n) time. In the above example I can get to the null matrix in 3 steps by subtracting these three matrices in order: Expected output: 1 0 0 0 1 0 0 0 1 0 0 1 1 0 0 0 1 0 0 1 0 0 0 1 1 0 0 I have coded an attempt, in which I am finding the first maximum value and creating the second matrices based on the index of that value. But for the above input I am getting 4 output matrices, which is wrong: My output: 1 0 0 0 1 0 0 0 1 0 1 0 1 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 1 0 1 0 My solution works for most of the test cases but fails for the one given above. Can someone give me some pointers on how to proceed, or find an algorithm that guarantees optimality? Test case that works: Input: 0 2 1 0 0 0 3 0 0 Output 0 1 0 0 0 0 1 0 0 0 1 0 0 0 0 1 0 0 0 0 1 0 0 0 1 0 0

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• Javascript Regex: Testing string for intelligent query

  - by Shyam

  Hi, I have a string that holds user input. This string can contain various types of data, like: a six digit id a zipcode that contains out of 4 digits and two alphanumeric characters a name (characters only) As I am using this string to search through a database, the query type is determined on the type of search, which i want to handle serverside using JavaScript (yes, I am using JavaScript serverside). Searching on StackOverflow, brought me some interesting information, like the .test-method, which seems perfect for my needs. The test-method returns either true or false based on the evaluation on the string using a regex object. I am using this page as a reference: http://www.javascriptkit.com/jsref/regexp.shtml So I am trying to determine the zipcode, by using the following very noobish regex. var r = /[A-Za-z]{2,2}/ As far I can understand, this should limit the amount of occurrences of alphanumeric characters to a maximum of two. See beneath the output of my JavaScript console. > var r = /[A-Za-z]{2,2}/ > var x = "2233AL" > r.test(x) true > var x = "2233A" > r.test(x) false > var x = "2233ALL" > r.test(x) true /* i want this to be false */ > A little help would be really appreciated!

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• how do I remove rows/columns from this matrix using python

  - by banditKing

  My matrix looks like this. ['Hotel', ' "excellent"', ' "very good"', ' "average"', ' "poor"', ' "terrible"', ' "cheapest"', ' "rank"', ' "total reviews"'] ['westin', ' 390', ' 291', ' 70', ' 43', ' 19', ' 215', ' 27', ' 813'] ['ramada', ' 136', ' 67', ' 53', ' 30', ' 24', ' 149', ' 49', ' 310 '] ['sutton place', '489', ' 293', ' 106', ' 39', ' 20', ' 299', ' 24', ' 947'] ['loden', ' 681', ' 134', ' 17', ' 5', ' 0', ' 199', ' 4', ' 837'] ['hampton inn downtown', ' 241', ' 166', ' 26', ' 5', ' 1', ' 159', ' 21', ' 439'] ['shangri la', ' 332', ' 45', ' 20', ' 8', ' 2', ' 325', ' 8', ' 407'] ['residence inn marriott', ' 22', ' 15', ' 5', ' 0', ' 0', ' 179', ' 35', ' 42'] ['pan pacific', ' 475', ' 262', ' 86', ' 29', ' 16', ' 249', ' 15', ' 868'] ['sheraton wall center', ' 277', ' 346', ' 150', ' 80', ' 26', ' 249', ' 45', ' 879'] ['westin bayshore', ' 390', ' 291', ' 70', ' 43', ' 19', ' 199', ' 813'] I want to remove the top row and the 0th column from this and create a new matrix. How do I do this? Normally in java or so Id use the following code: for (int y; y< matrix[x].length; y++) for(int x; x < matrix[Y].length; x++) { if(x == 0 || y == 0) { continue } else { new_matrix[x][y] = matrix[x][y]; } } Is there a way such as this in python to iterate and selectively copy elements? Thanks EDIT Im also trying to convert each matrix element from a string to a float as I iterate over the matrix. This my updated modified code based on the answer below. A = [] f = open("csv_test.csv",'rt') try: reader = csv.reader(f) for row in reader: A.append(row) finally: f.close() new_list = [row[1:] for row in A[1:]] l = np.array(new_list) l.astype(np.float32) print l However Im getting an error --> l.astype(np.float32) print l ValueError: setting an array element with a sequence.

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• C++ design question, container of instances and pointers

  - by Tom

  Hi all, Im wondering something. I have class Polygon, which composes a vector of Line (another class here) class Polygon { std::vector<Line> lines; public: const_iterator begin() const; const_iterator end() const; } On the other hand, I have a function, that calculates a vector of pointers to lines, and based on those lines, should return a pointer to a Polygon. Polygon* foo(Polygon& p){ std::vector<Line> lines = bar (p.begin(),p.end()); return new Polygon(lines); } Here's the question: I can always add a Polygon (vector Is there a better way that dereferencing each element of the vector and assigning it to the existing vector container? //for line in vector<Line*> v //vcopy is an instance of vector<Line> vcopy.push_back(*(v.at(i)) I think not, but I dont really like that approach. Hopefully, I will be able to convince the author of the class to change it, but I cant base my coding right now to that fact (and i'm scared of a performance hit). Thanks in advance.

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• C++ design question, container of instances and pointers

  - by Tom

  Hi all, Im wondering something. I have class Polygon, which composes a vector of Line (another class here) class Polygon { std::vector<Line> lines; public: const_iterator begin() const; const_iterator end() const; } On the other hand, I have a function, that calculates a vector of pointers to lines, and based on those lines, should return a pointer to a Polygon. Polygon* foo(Polygon& p){ std::vector<Line> lines = bar (p.begin(),p.end()); return new Polygon(lines); } Here's the question: I can always add a Polygon (vector Is there a better way that dereferencing each element of the vector and assigning it to the existing vector container? //for line in vector<Line*> v //vcopy is an instance of vector<Line> vcopy.push_back(*(v.at(i)) I think not, but I dont really like that approach. Hopefully, I will be able to convince the author of the class to change it, but I cant base my coding right now to that fact (and i'm scared of a performance hit). Thanks in advance.

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• C++ design question, container of instances and pointers

  - by Tom

  Hi all, Im wondering something. I have class Polygon, which composes a vector of Line (another class here) class Polygon { std::vector<Line> lines; public: const_iterator begin() const; const_iterator end() const; } On the other hand, I have a function, that calculates a vector of pointers to lines, and based on those lines, should return a pointer to a Polygon. Polygon* foo(Polygon& p){ std::vector<Line> lines = bar (p.begin(),p.end()); return new Polygon(lines); } Here's the question: I can always add a Polygon (vector Is there a better way that dereferencing each element of the vector and assigning it to the existing vector container? //for line in vector<Line*> v //vcopy is an instance of vector<Line> vcopy.push_back(*(v.at(i)) I think not, but I dont really like that approach. Hopefully, I will be able to convince the author of the class to change it, but I cant base my coding right now to that fact (and i'm scared of a performance hit). Thanks in advance.

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• Handling large (object) datasets with PHP

  - by Aron Rotteveel

  I am currently working on a project that extensively relies on the EAV model. Both entities as their attributes are individually represented by a model, sometimes extending other models (or at least, base models). This has worked quite well so far since most areas of the application only rely on filtered sets of entities, and not the entire dataset. Now, however, I need to parse the entire dataset (IE: all entities and all their attributes) in order to provide a sorting/filtering algorithm based on the attributes. The application currently consists of aproximately 2200 entities, each with aproximately 100 attributes. Every entity is represented by a single model (for example Client_Model_Entity) and has a protected property called $_attributes, which is an array of Attribute objects. Each entity object is about 500KB, which results in an incredible load on the server. With 2000 entities, this means a single task would take 1GB of RAM (and a lot of CPU time) in order to work, which is unacceptable. Are there any patterns or common approaches to iterating over such large datasets? Paging is not really an option, since everything has to be taken into account in order to provide the sorting algorithm.

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• Is there a case for parameterising using Abstract classes rather than Interfaces?

  - by Chris

  I'm currently developing a component based API that is heavily stateful. The top level components implement around a dozen interfaces each. The stock top-level components therefore sit ontop of a stack of Abstract implementations which in turn contain multiple mixin implementations and implement multiple mixin interfaces. So far, so good (I hope). The problem is that the base functionality is extremely complex to implement (1,000s of lines in 5 layers of base classes) and therefore I do not wish for component writers to implement the interfaces themselves but rather to extend my base classes (where all the boiler plate code is already written). If the API therefore accepts interfaces rather than references to the Abstract implementation that I wish for component writers to extends, then I have a risk that the implementer will not perform the validation that is both required and assumed by other areas of code. Therefore, my question is, is it sometimes valid to paramerise API methods using an abstract implementation reference rather than a reference to the interface(s) that it implements? Do you have an example of a well-designed API that uses this technique or am I trying to talk myself into bad-practice?

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