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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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  • 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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  • Python: Unpack arbitary length bits for database storage

    - by sberry2A
    I have a binary data format consisting of 18,000+ packed int64s, ints, shorts, bytes and chars. The data is packed to minimize it's size, so they don't always use byte sized chunks. For example, a number whose min and max value are 31, 32 respectively might be stored with a single bit where the actual value is bitvalue + min, so 0 is 31 and 1 is 32. I am looking for the most efficient way to unpack all of these for subsequent processing and database storage. Right now I am able to read any value by using either struct.unpack, or BitBuffer. I use struct.unpack for any data that starts on a bit where (bit-offset % 8 == 0 and data-length % 8 == 0) and I use BitBuffer for anything else. I know the offset and size of every packed piece of data, so what is going to be the fasted way to completely unpack them? Many thanks.

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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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  • how do i update database using ADODB.Recordset?

    - by every_answer_gets_a_point
    i am using excel to connect to a mysql database: Dim dpath, atime, rtime, lcalib, aname, rname, bstate, instrument As String Dim rs As ADODB.Recordset Set rs = New ADODB.Recordset ConnectDB With wsBooks rs.Open "batchinfo", oConn, adOpenKeyset, adLockOptimistic, adCmdTable Worksheets.Item("Report 1").Select dpath = Trim(Range("B2").Text) atime = Trim(Range("B3").Text) rtime = Trim(Range("B4").Text) lcalib = Trim(Range("B5").Text) aname = Trim(Range("B6").Text) rname = Trim(Range("B7").Text) bstate = Trim(Range("B8").Text) ' instrument = GetInstrFromXML(wbBook.FullName) With rs .AddNew ' create a new record ' add values to each field in the record .Fields("datapath") = dpath .Fields("analysistime") = atime .Fields("reporttime") = rtime .Fields("lastcalib") = lcalib .Fields("analystname") = aname .Fields("reportname") = rname .Fields("batchstate") = "bstate" .Fields("instrument") = "NA" .Update ' stores the new record End With what is the next step? how do i do an rs.execute?

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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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  • 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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  • 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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  • Sharepoint publishing cache- counter missing on WFE(Object Caching)

    - by Ryan
    I want to tune object caching in my sharepoint environment. The way to do is check sharepoint publishing cache counter through perfmon on your farm. I have one application server and 2 WFE but when I am trying to create counter for my WFE its showing Sharepoint publishing cache but I am not able to add any instance of it but when I select my application server I can see all the instances. But If I want to check publishing hit ratio i need to run this on WFE also ...correct me if I m wrong? How to resolve this issue? Also, how to check the hit ratio as our site is not go-live so we don't get enuf users to hit the site to check this thing. Does it means that I can tune it up only my site go live and real load will get on it. Thanks, Amit

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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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  • 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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  • 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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  • jquery: how to append elements to emtpy object

    - by John
    I want to create a set of options, that will be appended to every select in grid column <option> option 1 </option> <option> option 2 </option> ... <option> option N </option> but I don't know how to create a set of elements without parent element. appending to an empty jquery object doesn't work var options = $(''); options.append('<option></option>')

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  • embed tag for flash and w3c

    - by drav
    when validating a site using w3c validator it tells me the tag is not valid markup. So i take it out and it works on safari/chrome but not firefox(3.5.x) but validates fine. Is there something in the tag i must add in order for firefox to display flash.

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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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  • 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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  • 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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  • 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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  • 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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  • Improve this generic abstract class

    - by Keivan
    I have the following abstract class design, I was wondering if anyone can suggest any improvements in terms of stronger enforcement of our requirements or simplifying implementing of the ControllerBase. //Dependency Provider base public abstract class ControllerBase<TContract, TType> where TType : TContract, class { public static TContract Instance { get { return ComponentFactory.GetComponent<TContract, TType>(); } } public TContract GetComponent<TContract, TType>() where TType : TContract, class { component = (TType)Activator.CreateInstance(typeof(TType), true); RegisterComponentInstance<TContract>(component); } } //Contract public interface IController { void DoThing(); } //Actual Class Logic public class Controller: ControllerBase<IController,Controller> { public void DoThing(); //internal constructor internal Controller(){} } //Usage public static void Main() { Controller.Instance.DoThing(); } The following facts should always be true, TType should always implement TContract (Enforced using a generic constraint) TContract must be an interface (Can't find a way to enforce it) TType shouldn't have public constructor, just an internal one, is there any way to Enforce that using ControllerBase? TType must be an concrete class (Didn't include New() as a generic constrain since the constructors should be marked as Internal)

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  • How can I set my deployment options to script the incremental release of a Visual Studio 2010 databa

    - by littlechris
    I've just started using a VS2010 database project to manage the release of an update to an existing database. I want the deployment option to generate a script that will contain the commands to change my existing database rather than create an entirely new one. E.g I have 10 existing tables - one of which I drop in the new version and I create some new sprocs. I only want the deploy to script the Drop table and Create Procedure commands. I am using VS2010 Premium. Thanks!

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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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