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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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  • best database design for city zip & state tables

    - by ryan a
    My application will need to reference addresses. Street info will be stored with my main objects but the rest needs to be stored seperately to reduce redundancy. How should I store/retrieve ZIPs, cities and states? Here are some of my ideas. single table solution (cant do relationships) [locations] locationID locationParent (FK for locationID - 0 for state entries) locationName (city, state) locationZIP two tables (with relationships, FK constraints, ref integrity) [state] stateID stateName [city] cityID stateID (FK for state.stateID) cityName zipCode three tables [state] stateID stateName [city] cityID stateID (FK for state.stateID) cityName [zip] zipID cityID (FK for city.cityID) zipName Then I read into ZIP codes amd how they are assigned. They aren't specifically related to cities. Some cities have more than one ZIP (ok will still work) but some ZIPs are in more than one city (oh snap) and some other ZIPs (very few) are in more than one state! Also some ZIPs are not even in the same state as the address they belong to at all. Seems ZIPs are made for carrier route identification and some remote places are best served by post offices in neighboring cities or states. Does anybody know of a good (not perfect) solution that takes this into consideration to minimize discrepencies as the database grows?

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  • JPA + EJB + JSF: how can design complicated query

    - by Harry Pham
    I am using netbean 6.8 btw. Let say that I have 4 different tables: Company, Facility, Project, and Document. So the relationship is this. A company can have multiple facilities. A facility can have multiple projects, and a project can have multiple documents. Company: +companyNum: PK +facilityNum: FK Facility: +facilityNum: PK +projectNum: FK Project: +projectNum: PK +drawingNum: FK So when I create Entity Class From Database in netbean 6.8, I have 4 entity classes that named after the above 4 tables. So if I want to see all the Document in the database, then it is easy. In my SessionBean, I would do this: @PersistenceContext private EntityManager em; List<Document> documents = em.createNamedQuery("Document.findAll").getResultList(); However, that is not all what I need. Let say that I want to know all the Document from a particular Company, or all the Document from a particular Project from a particular Facility from a particular Company. I am very new to JPA + EJB + JSF as a whole. Please help me out.

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  • Design advices for quick navigation between view

    - by Thomas Joulin
    Usually, when a View requires a lot of bindings, or some UI Elements like a Bing Map, it takes a "while" to load (like between half a second and a second). I don't want a delay between a "tap" action (like tapping an element on a ListBox) and the navigation action (displaying a new page). I don't mind displaying the page progressively. For example, for a Bing Map, I don't mind displaying a black page with only a title, and a second later, having the Map appear. What are the best practices ? It could post a sample if i'm not clear enough

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  • (Python) algorithm to randomly select a key based on proportionality/weight

    - by LaundroMat
    Hi - I'm a bit at a loss as to how to find a clean algorithm for doing the following: Suppose I have a dict k: >>> k = {'A': 68, 'B': 62, 'C': 47, 'D': 16, 'E': 81} I now want to randomly select one of these keys, based on the 'weight' they have in the total (i.e. sum) amount of keys. >>> sum(k.values()) >>> 274 So that there's a >>> 68.0/274.0 >>> 0.24817518248175183 24.81% percent change that A is selected. How would you write an algorithm that takes care of this? In other words, that makes sure that on 10.000 random picks, A will be selected 2.481 times?

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  • Ruby 1.9: turn these 4 arrays into hash of key/value pairs

    - by randombits
    I have four arrays that are coming in from the client. Let's say that there is an array of names, birth dates, favorite color and location. The idea is I want a hash later where each name will have a hash with respective attributes: Example date coming from the client: [name0, name1, name2, name3] [loc0, loc1] [favcololor0, favcolor1] [bd0, bd1, bd2, bd3, bd4, bd5] Output I'd like to achieve: name0 => { location => loc0, favcolor => favcolor0, bd => bd0 } name1 => { location => loc1, favcolor => favcolor1, bd => bd1 } name2 => { location => nil, favcolor => nil, bd => bd2 } name3 => { location => nil, favcolor => nil, bd => bd3 } I want to have an array at the end of the day where I can iterate and work on each particular person hash. There need not be an equivalent number of values in each array. Meaning, names are required.. and I might receive 5 of them, but I only might receive 3 birth dates, 2 favorite colors and 1 location. Every missing value will result in a nil. How does one make that kind of data structure with Ruby 1.9?

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  • Windows Macro + Hot Key - Paste Without Formatting

    - by JasonStoltz
    Not sure if this appropriate to put as a question or not? It's sort of a scripting question I think. Just down vote me if not :p Basically, what I'm looking for is a way to push a windows hotkey and have whatever text is in the clipboard be stripped of formatting. An example of what the macro could do: I push (whatever hotkey combo here) open notepad.exe Paste to notepad from clipboard Select all text in notepad Copy/Cut all text from notepad Close notepad I'm just wondering if someone has done something like this before, or knows how it could be accomplished. I think this could be a huge time-saver for almost anyone. I find myself doing this all the time when cutting and pasting between different office applications, etc.

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  • FacebookRestClientException: A session key is required for calling this method in

    - by simple
    I have a app, that is used in the fanpage, so basically I am showing up the user request/invite form, after submission which refers to my server and I get friends ids(from $_POST) and info about user who sent invite, to get user info I am using $user = $this->_facebook->api_client->users_getLoggedInUser(); $dataToRetrive = array(....); $usersInfo = $this->_facebook->api_client->users_getInfo($user,$dataToRetrive); and then I redirect to fan page again in FF it is working fine but OPera and Chrome it is loosing the session.

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  • php Undefined index but i can access that key anyways

    - by Linas
    I just don't get it, i know what the error means i know how to fix it but it seems to be more of a php bug, i have an array returned from some function which looks like this when i use var_dump: array(1) { ["89512480-1884-11e2-aee6-618bca23e5b1"]=> array(5) { ["created"]=> string(10) "1350514509" ["expires"]=> string(10) "1351724109" ["token"]=> string(40) "81fa1895a6d5d4cb11efae8e71adf98fbdbfb5ca" ["user_agent"]=> string(40) "6ab18a2ea1d4b17d67713e416b07d46bf2f4d03b" ["username"]=> string(4) "test" } } array(0) { } but if i try for example: echo $token['89512480-1884-11e2-aee6-618bca23e5b1']['user_agent']; it shows me the value, but at the same time i get that annoying error, what the hell?

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  • Design question?

    - by Mohamed
    I am building music app, where user can do several tasks including but not limited to listening song, like song, recommend song to a friend and extra. currently I have this model: class Activity(models.Model): activity = models.TextField() user = models.ForeignKey(User) date = models.DateTimeField(auto_now=True) so far I thought about two solutions. 1. saving a string to database. e.g "you listened song xyz" 2. create a dictionary about the activity and save to the database using pickle or json. e.g. dict_ = {"activity_type":"listening", "song":song_obj} I am leaning to the second implementation, but not quite sure. so what do you think about those two methods? do you know better way to achieve the goal?

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  • Convert PHP array into Key => Value Array

    - by Feature
    Total PHP Noob and I couldn't find an answer to this specific problem. Hope someone can help! $myvar is an array that looks like this: Array ( [aid] = Array ( [0] = 2 [1] = 1 ) [oid] = Array( [0] = 2 [1] = 1 ) ) And I need to set a new variable (called $attributes) to something that looks like this: $attributes = array($myvar['aid'][0] => $myvar['oid'][0], $myvar['aid'][1] => $myvar['oid'][1], etc...); And, of course, $myvar may contain many more items... How do I iterate through $myvar and build the $attributes variable?

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  • Hibernate Many-To-One Foreign Key Default 0

    - by user573648
    I have a table where the the parent object has an optional many-to-one relationship. The problem is that the table is setup to default the fkey column to 0. When selecting, using fetch="join", etc-- the default of 0 on the fkey is being used to try over and over to select from another table for the ID 0. Of course this doesn't exist, but how can I tell Hibernate to treat a value of 0 to be the same as NULL-- to not cycle through 20+ times in fetching a relationship which doesn't exist? <many-to-one name="device" lazy="false" class="Device" not-null="true" access="field" cascade="none" not-found="ignore"> <column name="DEVICEID" default="0" not-null="false"/>

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  • Find messages from certain key till certain key while being able to remove stale keys.

    - by Alfred
    My problem Let's say I add messages to some sort of datastructure: 1. "dude" 2. "where" 3. "is" 4. "my" 5. "car" Asking for messages from index[4,5] should return: "my","car". Next let's assume that after a while I would like to purge old messages because they aren't useful anymore and I want to save memory. Let's say at time x messages[1-3] became stale. I assume that it would be most efficient to just do the deletion once every x seconds. Next my datastructure should contain: 4. "my" 5. "car" My solution? I was thinking of using a concurrentskiplistset or concurrentskiplist map. Also I was thinking of deleting the old messages from inside a newSingleThreadScheduledExecutor. I would like to know how you would implement(efficiently/thread-safe) this or maybe use a library?

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  • "2d Search" in Solr or how to get the best item of the multivalued field 'items'?

    - by Karussell
    The title is a bit awkward but I couldn't found a better one. My problem is as follows: I have several users stored as documents and I am storing several key-value-pairs or items (which have an id) for each document. Now, if I apply highlighting I can get the first n items. If you have several hundreds of such items this highlighting is necessary and works nicely. But there are two problems: The highlighted text won't contain the id and so retrieving additional information of the highlighted item text is ugly. E.g. you need to store the id in the text so that the highlighter returns it. Adding the id to the hl.fl parameter does not help. You will not get the most relevant n-items. You will get the first n items ... So how can I find the best items of a documents with multiple such items? I will now add my own findings as answers, but as I will point out. Each of them has its drawbacks. Hopefully anyone of you can point me to a better solution.

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  • Hibernate - One design problem

    - by Yatendra Goel
    I am learning Hibernate from the tutorial on JBoss website. I have a confusion in a code example located here. There is a Cat class code at 4.1. A simple POJO example. This Cat class has a reference to his mother as private Cat mother; Q1. If the class has an identifier property as id, then wouldn't it be better to store the cat's mother's id instead of cat's mother object. means instead of private Cat mother; wouldn't it be better to have private long motherId; `

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  • Disable Foreign Key Exposure in Entity Framework?

    - by davemackey
    When I originally created a Dynamic Data project I told it to expose the foreign keys, but now I can't make mappings between two entities b/c of the foreign keys. When I click on mapping details while focused on my association I receive the message: Mappings are not allow for an association over exposed foreign keys. So I'd like to disable the exposure of the foreign keys but am unsure how to do this without creating a new Entity Model from scratch. I'm not far along - so that wouldn't be hard, but I imagine there must be a programmatic switch for this?

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  • Design for fastest page download

    - by mexxican
    I have a file with millions of URLs/IPs and have to write a program to download the pages really fast. The connection rate should be at least 6000/s and file download speed at least 2000 with avg. 15kb file size. The network bandwidth is 1 Gbps. My approach so far has been: Creating 600 socket threads with each having 60 sockets and using WSAEventSelect to wait for data to read. As soon as a file download is complete, add that memory address(of the downloaded file) to a pipeline( a simple vector ) and fire another request. When the total download is more than 50Mb among all socket threads, write all the files downloaded to the disk and free the memory. So far, this approach has been not very successful with the rate at which I could hit not shooting beyond 2900 connections/s and downloaded data rate even less. Can somebody suggest an alternative approach which could give me better stats. Also I am working windows server 2008 machine with 8 Gig of memory. Also, do we need to hack the kernel so as we could use more threads and memory. Currently I can create a max. of 1500 threads and memory usage not going beyond 2 gigs [ which technically should be much more as this is a 64-bit machine ]. And IOCP is out of question as I have no experience in that so far and have to fix this application today. Thanks Guys!

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  • REST design: what verb and resource name to use for a filtering service

    - by kabaros
    I am developing a cleanup/filtering service that has a method that receives a list of objects serialized in xml, and apply some filtering rules to return a subset of those objects. In a REST-ful service, what verb shall I use for such a method? I thought that GET is a natural choice, but I have to put the serialized XML in the body of the request which works but feels incorrect. The other verbs don't seem to fit semantically. What is a good way to define that Service interface? Naming the resource /Cleanup or /Filter seems weird mainly because in the examples I see online, it is always a name rather than a verb being used for resource name. Am I right to feel that REST services are better suited for CRUD operations and you start bending the rules in situations like this service? If yes, am I then making a wrong architectural choice. I've pushed to develop this service in REST-ful style (as opposed to SOAP) for simplicity, but such awkward cases happen a lot and make me feel like I am missing something. Either choosing REST where it shouldn't be used or may be over-thinking some stuff that doesn't really matter? In that case, what really matters?

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  • Entity Framework EntityKey / Foreign Key problem.

    - by Ronny176
    Hi, I keep getting the same error: Entities in 'VlaamseOverheidMeterEntities.ObjectMeter' participate in the 'FK_ObjectMeter_Meter' relationship. 0 related 'Meter' were found. 1 'Meter' is expected. I have the following table structure: Meter 1 <- * ObjectMeter * - 1 VO_Object It is always the same scenario: The first meter is added to the database, the second meter gives the error above. I have the following code in my manager: public List<string> addTemporary(string username, string meterNaam, string readingType, string parentID) { Meter meter = new Meter(); VO_Object voObject = objectManager.getObjectByID(parentID); ObjectMeter objMeter = new ObjectMeter(); meter.readingType = (int)Enum.Parse(typeof(ReadingType), readingType); meter.isActive = true; meter.name = meterNaam; meter.startDate = DateTime.Now; meter.endDate = DateTime.Now.AddYears(6000); meter.uniqueIdentifier = "N/A"; meter.meterType = (int)Enum.Parse(typeof(MeterType), "NA"); meter.meterCategory = (int)Enum.Parse(typeof(MeterCategory), "NA"); meter.energyType = (int)Enum.Parse(typeof(EnergyType), "NA"); meter.utilityType = (int)Enum.Parse(typeof(UtilityType), "NA"); meter.unitOfMeasure = (int)Enum.Parse(typeof(UnitOfMeasure), "NA"); objMeter.valid_from = meter.startDate; objMeter.valid_until = meter.endDate; objMeter.Meter = meter; objMeter.VO_Object = voObject; createMeter(meter); List<String> str = new List<string>(); str.Add("" + meter.meterID); str.Add(meter.name); return str; } and this in my Dao Class which links to the database: internal void CreateMeter(Meter _meter) { _entities.AddToMeter(_meter); _entities.SaveChanges(); } Can someone please explain this error? Ronald

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  • How to create unique user key

    - by Grayson Mitchell
    Scenario: I have a fairly generic table (Data), that has an identity column. The data in this table is grouped (lets say by city). The users need an identifier in order for printing on paper forms, etc. The users can only access their cites data, so if they use the identity column for this purpose they will see odd numbers (e.g. a 'New York' user might see 1,37,2028... as the listed keys. Idealy they would see 1,2,3... (or something similar) The problem of course is concurrency, this being a web application you can't just have something like: UserId = Select Count(*)+1 from Data Where City='New York' Has anyone come up with any cunning ways around this problem?

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  • Best way to design a class in python

    - by Fraz
    So, this is more like a philosophical question for someone who is trying to understand classes. Most of time, how i use class is actually a very bad way to use it. I think of a lot of functions and after a time just indent the code and makes it a class and replacing few stuff with self.variable if a variable is repeated a lot. (I know its bad practise) But anyways... What i am asking is: class FooBar: def __init__(self,foo,bar): self._foo = foo self._bar = bar self.ans = self.__execute() def __execute(self): return something(self._foo, self._bar) Now there are many ways to do this: class FooBar: def __init__(self,foo): self._foo = foo def execute(self,bar): return something(self._foo, bar) Can you suggest which one is bad and which one is worse? or any other way to do this. This is just a toy example (offcourse). I mean, there is no need to have a class here if there is one function.. but lets say in __execute something() calls a whole set of other methods.. ?? Thanks

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  • PHP: How do I access child properties from a method in a base object?

    - by Nick
    I'd like for all of my objects to be able to return a JSON string of themselves. So I created a base class for all of my objects to extend, with an AsJSON() method: class BaseObject { public function AsJSON() { $JSON=array(); foreach ($this as $key = $value) { if(is_null($value)) continue; $JSON[$key] = $value; } return json_encode($JSON); } } And then extend my child classes from that: class Package extends BaseObject { ... } So in my code, I expect to do this: $Box = new Package; $Box-SetID('123'); $Box-SetName('12x8x6'); $Box-SetBoxX('12'); $Box-SetBoxY('8'); $Box-SetBoxZ('6'); echo $Box-AsJSON(); But the JSON string it returns only contains the BaseClass's properties, not the child properties. How do I modify my AsJSON() function so that $this refers to the child's properties, not the parent's?

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  • java template design

    - by Sean Nguyen
    Hi, I have this class: public class Converter { private Logger logger = Logger.getLogger(Converter.class); public String convert(String s){ if (s == null) throw new IllegalArgumentException("input can't be null"); logger.debug("Input = " + s); String r = s + "abc"; logger.debug("Output = " + s); return r; } public Integer convert(Integer s){ if (s == null) throw new IllegalArgumentException("input can't be null"); logger.debug("Input = " + s); Integer r = s + 10; logger.debug("Output = " + s); return r; } } The above 2 methods are very similar so I want to create a template to do the similar things and delegate the actual work to the approriate class. But I also want to easily extends this frame work without changing the template. So for example: public class ConverterTemplate { private Logger logger = Logger.getLogger(Converter.class); public Object convert(Object s){ if (s == null) throw new IllegalArgumentException("input can't be null"); logger.debug("Input = " + s); Object r = doConverter(); logger.debug("Output = " + s); return r; } protected abstract Object doConverter(Object arg); } public class MyConverter extends ConverterTemplate { protected String doConverter(String str) { String r = str + "abc"; return r; } protected Integer doConverter(Integer arg) { Integer r = arg + 10; return r; } } But that doesn't work. Can anybody suggest me a better way to do that? I want to achieve 2 goals: 1. A template that is extensible and does all the similar work for me. 2. I ant to minimize the number of extended class. Thanks,

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