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  • cross-platform frameworks for storage + metadata?

    - by Jason S
    I don't quite know what to use for terminology, so bear with me... Are there any cross-platform frameworks out there that facilitate a kind of "virtual file storage" to encapsulate adding files along with a database of metadata? I'm thinking about something along the lines of iTunes or iPhoto, where the program manages a whole bunch of files (in those cases audio or image files) and has a database of metadata so you can organize/find those files easily. I'd like to cobble together something along those lines for files in general. edit: I am hesitant to store files in a database alone, e.g. MySQL, as there would be potentially tens of gigabytes in my application (this issue has been mentioned in several SO posts, see this one that gives several links to others). I'm looking at CouchDB though and maybe it has promise....

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  • Initial capacity of collection types, i.e. Dictionary, List

    - by Neil N
    Certain collection types in .Net have an optional "Initial Capacity" constructor param. i.e. Dictionary<string, string> something = new Dictionary<string,string>(20); List<string> anything = new List<string>(50); I can't seem to find what the default initial capacity is for these objects on MSDN. If I know I will only be storing 12 or so items in a dictionary, doesn't it make sense to set the initial capacity to something like 20? My reasoning is, assuming the capacity grows like it does for a StringBuiler, which doubles each time the capacity is hit, and each re-allocation is costly, why not pre-set the size to something you know will hold your data, with some extra room just in case? If the initial capacity is 100, and I know I will only need a dozen or so, it seems as though the rest of that allocated RAM is allocated for nothing. Please spare me the "premature optimization" speil for the O(n^n)th time. I know it won't make my apps any faster or save any meaningful amount of memory, this is mostly out of curiosity.

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  • referesh datagridview after database update in vb.net

    - by Gbolahan
    Dim myQuery = "UPDATE table1 SET data= CONCAT (data,'" & vbCrLf & "[ " & Date.Now() & " ]" & " " & "[" & getCN() & "]" & " " & txtTelenotes.Text & "[ item1 ]" & "') WHERE id='" & txtID.Text & "'" myCommand.Connection = conn myCommand.CommandText = myQuery myAdapter.SelectCommand = myCommand Dim myData As MySqlDataReader myData = myCommand.ExecuteReader() txtTelenotes.Text = "" dgvREcord.Refresh() tried refreshing the datagridview using dgvREcord.Refresh() but it does not load the changes form the database. Any help Pls.. Thanks.

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  • Java generics question

    - by user247866
    So I have 3 classes. Abstract class A Class B extends class A independent Class C In class D that contains the main method, I create a list of instances of class B List<B> b = methodCall(); // the method returns a list of instances of class B Now in class C I have one method that is common to both A and B, and hence I don't want to duplicate it. I want to have one method that takes as input an instance of class A, as follows: public void someMethod(List<A> a) However, when I do: C c = new C(); c.someMethod(b); I get an error that some-method is not applicable for the argument List<B>, instead it's expecting to get List<A>. Is there a good way to fix this problem? Many thanks!

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  • C#: why have all static methods/variables in a non-static class?

    - by Craig Johnston
    I have come across a class which is non-static, but all the methods and variables are static. Eg: public class Class1 { private static string String1 = "one"; private static string String2 = "two"; public static void PrintStrings(string str1, string str2) { ... All the variables are static across all instances, so there is no point having separate instances of the class. Is there any reason to create a class such as this?

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  • looping through an object (tree)

    - by Val
    Is there a way (in jquery or javascript) to loop through each object and it's children and gandchildren and so on. if so... can i also read their name? example foo :{ bar:'', child:{ grand:{ greatgrand: { //and so on } } } } so the loop should do something like this... loop start if(nameof == 'child'){ //do something } if(nameof == 'bar'){ //do something } if(nameof =='grand'){ //do something } loop end I know this is stupid code but i tried to make it understandable :) btw this is for a jquery UI, as i am clueless how to go on about this. thanks

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  • Custom class object in Initialization list

    - by Michael
    I have a class Bar: class Bar { public: Bar(void); ~Bar(void); }; And a class Foo that gets a reference to Bar object as a constructor parameter and needs to save it in a private member bar_ : class Foo { private: Bar& bar_; public: Foo(Bar& bar) : bar_(bar) {} ~Foo(void) {} }; This doesn't compile : overloaded member function not found in 'Parser' missing type specifier - int assumed. Note: C++ does not support default-int Now i suspect couple of things that i need to assure, the second error is for Bar& bar_; declaration in Foo. Do i need to use an explicit constructor when declaring bar_ ? I am interested in learning how the compiler works regarding this matter, so a detailed explanation would be highly appreciated. Thanks.

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  • How to integrate access control with my ORM in a .net windows form application?

    - by Ying
    I am developing a general database query tools, a .Net 3.5 Windows Form application. In order to make the presentation layer is independent of the database layer. I use an ORM framework, XPO from DevExpress. But, I have no access control function built in. I surfed Internet and I found in WCF Data Services, there is an interesting concept, Interceptor, which is following AOP(Aspect Oriented Programming). I am wondering who has such an experience to build access control in ORM. My basic requirement is : It should be a general method and controlled by users in runtime. So any hard coding is not acceptable. It could be based on attribute, database table, or even an external assembly. I am willing to buy a ready solution. According to the idea of AOP, an access control function can be integrated with existing functions easily and nearly not knowingly to the previous developer;) Any suggestions are welcome.

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  • What patterns exist for web application development?

    - by DaveDev
    I understand that MVC & MVP are design patterns that are commonly used for web development, as well as ASP.NET WebForms (more of an anti-pattern, really!). What other patterns are used in web application development? I'm not necessarily saying I want to learn/use new patterns just to be different - I do believe there's a lot of value in taking the conventional route - but I think it's good to know what else is out there to be able to properly understand what I'm currently working with. Thanks.

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  • Partial class or "chained inheritance"

    - by Charlie boy
    Hi From my understanding partial classes are a bit frowned upon by professional developers, but I've come over a bit of an issue; I have made an implementation of the RichTextBox control that uses user32.dll calls for faster editing of large texts. That results in quite a bit of code. Then I added spellchecking capabilities to the control, this was made in another class inheriting RichTextBox control as well. That also makes up a bit of code. These two functionalities are quite separate but I would like them to be merged so that I can drop one control on my form that has both fast editing capabilities and spellchecking built in. I feel that simply adding the code form one class to the other would result in a too large code file, especially since there are two very distinct areas of functionality, so I seem to need another approach. Now to my question; To merge these two classes should I make the spellchecking RichTextBox inherit from the fast edit one, that in turn inherits RichTextBox? Or should I make the two classes partials of a single class and thus making them more “equal” so to speak? This is more of a question of OO principles and exercise on my part than me trying to reinvent the wheel, I know there are plenty of good text editing controls out there. But this is just a hobby for me and I just want to know how this kind of solution would be managed by a professional. Thanks!

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  • C++ inheritance and member function pointers

    - by smh
    In C++, can member function pointers be used to point to derived (or even base) class members? EDIT: Perhaps an example will help. Suppose we have a hierarchy of three classes X, Y, Z in order of inheritance. Y therefore has a base class X and a derived class Z. Now we can define a member function pointer p for class Y. This is written as: void (Y::*p)(); (For simplicity, I'll assume we're only interested in functions with the signature void f() ) This pointer p can now be used to point to member functions of class Y. This question (two questions, really) is then: Can p be used to point to a function in the derived class Z? Can p be used to point to a function in the base class X?

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  • Printing the address of a struct object

    - by bdhar
    I have a struct like this typedef struct _somestruct { int a; int b; }SOMESTRUCT,*LPSOMESTRUCT; I am creating an object for the struct and trying to print it's address like this int main() { LPSOMESTRUCT val = (LPSOMESTRUCT)malloc(sizeof(SOMESTRUCT)); printf("0%x\n", val); return 0; } ..and I get this warning warning C4313: 'printf' : '%x' in format string conflicts with argument 1 of type 'LPSOMESTRUCT' So, I tried to cast the address to int like this printf("0%x\n", static_cast<int>(val)); But I get this error: error C2440: 'static_cast' : cannot convert from 'LPSOMESTRUCT' to 'int' What am I missing here? How to avoid this warning? Thanks.

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  • failure on creating a Scikits.TimeSeries object

    - by user311906
    Hi All I am trying to create a scikit.timeseries object starting from 2 datetime objects. If I understood correctly it should be possible to create a scikits.timeseries starting from datetime objects. I try the following code but it says that Insufficient parameters. The 2 datetime differs for few microseconds. In this case what should be the value for freq parameter? Is what I am trying allowed? In theory, since timeseries can be based on datetime objects it should be possible to hanlde up to microsecond , is this correct? I think that this is not really clear to me. Regards Eo import datetime import sckilits.timeseries as ts tm1 = datetime.datetime( 2010,1,1, 10,10,2, 123456 ) tm2 = datetime.datetime( 2010,1,1, 10,10,2, 345678 ) d = [ tm1, tm2 ] tseries = ts.time_series( dates=d ) tseries = ts.time_series( d )

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  • How should I declare default values for instance variables in Python?

    - by int3
    Should I give my class members default values like this: class Foo: num = 1 or like this? class Foo: def __init__(self): self.num = 1 In this question I discovered that in both cases, bar = Foo() bar.num += 1 is a well-defined operation. I understand that the first method will give me a class variable while the second one will not. However, if I do not require a class variable, but only need to set a default value for my instance variables, are both methods equally good? Or one of them more 'pythonic' than the other? One thing I've noticed is that in the Django tutorial, they use the second method to declare Models. Personally I think the second method is more elegant, but I'd like to know what the 'standard' way is.

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  • To Interface or Not?: Creating a polymorphic model relationship in Ruby on Rails dynamically..

    - by Globalkeith
    Please bear with me for a moment as I try to explain exactly what I would like to achieve. In my Ruby on Rails application I have a model called Page. It represents a web page. I would like to enable the user to arbitrarily attach components to the page. Some examples of "components" would be Picture, PictureCollection, Video, VideoCollection, Background, Audio, Form, Comments. Currently I have a direct relationship between Page and Picture like this: class Page < ActiveRecord::Base has_many :pictures, :as => :imageable, :dependent => :destroy end class Picture < ActiveRecord::Base belongs_to :imageable, :polymorphic => true end This relationship enables the user to associate an arbitrary number of Pictures to the page. Now if I want to provide multiple collections i would need an additional model: class PictureCollection < ActiveRecord::Base belongs_to :collectionable, :polymorphic => true has_many :pictures, :as => :imageable, :dependent => :destroy end And alter Page to reference the new model: class Page < ActiveRecord::Base has_many :picture_collections, :as => :collectionable, :dependent => :destroy end Now it would be possible for the user to add any number of image collections to the page. However this is still very static in term of the :picture_collections reference in the Page model. If I add another "component", for example :video_collections, I would need to declare another reference in page for that component type. So my question is this: Do I need to add a new reference for each component type, or is there some other way? In Actionscript/Java I would declare an interface Component and make all components implement that interface, then I could just have a single attribute :components which contains all of the dynamically associated model objects. This is Rails, and I'm sure there is a great way to achieve this, but its a tricky one to Google. Perhaps you good people have some wise suggestions. Thanks in advance for taking the time to read and answer this.

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  • Do you think functional language is good for applications that have a lot of business rules but very

    - by StackUnderflow
    I am convinced that functional programming is an excellent choice when it comes to applications that require a lot of computation (data mining, AI, nlp etc). But is it wise to use functional programming for a typical enterprise application where there are a lot of business rules but not much in terms of computation? Please disregard the fact that there are very few people using functional programming and that it's kind of tough. Thanks

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  • Java JPA @OneToMany neededs to reciprocate @ManyToOne?

    - by bguiz
    Create Table A ( ID varchar(8), Primary Key(ID) ); Create Table B ( ID varchar(8), A_ID varchar(8), Primary Key(ID), Foreign Key(A_ID) References A(ID) ); Given that I have created two tables using the SQL statements above, and I want to create Entity classes for them, for the class B, I have these member attributes: @Id @Column(name = "ID", nullable = false, length = 8) private String id; @JoinColumn(name = "A_ID", referencedColumnName = "ID", nullable = false) @ManyToOne(optional = false) private A AId; In class A, do I need to reciprocate the many-to-one relationship? @Id @Column(name = "ID", nullable = false, length = 8) private String id; @OneToMany(cascade = CascadeType.ALL, mappedBy = "AId") private List<B> BList; //<-- Is this attribute necessary? Is it a necessary or a good idea to have a reciprocal @OneToMany for the @ManyToOne? If I make the design decision to leave out the @OneToMany annotated attribute now, will come back to bite me further down.

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  • Find Exact difference between two dates

    - by iPhone Fun
    Hi all , I want some changes in the date comparison. In my application I am comparing two dates and getting difference as number of Days, but if there is only one day difference the system shows me 0 as a difference of days. I do use following code NSDateFormatter *date_formater=[[NSDateFormatter alloc]init]; [date_formater setDateFormat:@"MMM dd,YYYY"]; NSString *now=[NSString stringWithFormat:@"%@",[date_formater stringFromDate:[NSDate date]]]; LblTodayDate.text = [NSString stringWithFormat:@"%@",[NSString stringWithFormat:@"%@",now]]; NSDate *dateofevent = [[NSUserDefaults standardUserDefaults] valueForKey:@"CeremonyDate_"]; NSDate *endDate =dateofevent; NSDate *startDate = [NSDate date]; gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar]; unsigned int unitFlags = NSDayCalendarUnit; NSDateComponents *components = [gregorian components:unitFlags fromDate:startDate toDate:endDate options:0]; int days = [components day]; I found some solutions that If we make the time as 00:00:00 for comparision then it will show me proper answer , I am right or wrong i don't know. Please help me to solve the issue

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  • C# Linq: Restructuring object

    - by Ben
    I'd like to take an object like this: SortedList<string, SortedList<int, SortedList<DateTime, double>>> Data and, for a given 'int' value (key of first nested sorted list), restructure it like this: SortedList<DateTime, SortedList<string, double>> or, better yet, this: SortedList<DateTime, double[]> where each 'double[]' has as many elements as there are KeyValue pairs in the SortedList. I'm guessing Linq is the way to go, but can't figure it out. Thanks for any suggestions.

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  • Problem saving Text file in database using Hibernate

    - by Marquinio
    I'm having a problem saving large text files to MySQL database. If the text file size is around 5KB it successfully saves. If file is 148KB then I get this error from Hibernate: org.hibernate.exception.DataException: Could not execute JDBC batch update These is the SQL shows by Hibernate: Hibernate: insert into file_table (ID,FILE) values (?, ?) And in my hibernate file I'm using java.sql.Blob to store the file. Anyone knows why it fails to save a file size of 148KB but if I open that same file, cut it down to around 5KB, it will successfully save it? I thought the default limit was I think 2GB? This is weird. Thanks.

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  • java protected method accessibility

    - by JavaUser
    In the below code the Consumer class can access the protected method of Parent class.How is it possible since there is no relation between Parent and Consumer class.Please explain class Parent { public void method1(){ System.out.println("PUBLIC METHOD"); } private void method2(){ System.out.println("PRIVATE METHOD"); } protected void method3(){ System.out.println("PROTECTED METHOD"); } } public class Consumer { public static void main(String[] args){ Parent parentObj = new Parent(); parentObj.method1(); //parentObj.method2(); parentObj.method3(); } } Thanks

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  • Magento coupon entities in database

    - by koramaiku
    I'm trying to develop a Magento plugin which involves using coupons. Apparently after looking around I found I found a source that mentions use of a 'salesrule' table for coupons. However when I looked at my database i couldn't find it. However I did find 3 tables that had mention 'coupon' called 'coupon_aggregated', 'coupon_aggregated_order', and 'coupon_aggregated_updated'. I just wanted to know what is the difference between the 3 tables so I can start using them? I am on the latest version of Magento. Thanks guys in advance.

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