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• Is there a way to cause a new C++ class instance to fail, if certain conditions in the contructor ar

  - by Jim Fell

  As I understand it, when a new class is instantiated in C++, a pointer to the new class is returned, or NULL, if there is insufficient memory. I am writing a class that initializes a linked list in the constructor. If there is an error while initializing the list, I would like the class instantiator to return NULL. For example: MyClass * pRags = new MyClass; If the linked list in the MyClass constructor fails to initialize properly, I would like pRags to equal NULL. I know that I can use flags and additional checks to do this, but I would like to avoid that, if possible. Does anyone know of a way to do this? Thanks.

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• Three boolean values saved in one tinyint

  - by Casper

  Hello, probably a simple question but I seem to be suffering from programmer's block. :) I have three boolean values: A, B, and C. I would like to save the state combination as an unsigned tinyint (max 255) into a database and be able to derive the states from the saved integer. Even though there are only a limited number of combinations, I would like to avoid hard-coding each state combination to a specific value (something like if A=true and B=true has the value 1). I tried to assign values to the variables so (A=1, B=2, C=3) and then adding, but I can't differentiate between A and B being true from i.e. only C being true. I am stumped but pretty sure that it is possible. Thanks

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• website is very slow on IE

  - by Bhupi

  Hi, I need to know what can be the main reasons (apart from the basics like grouping CSS selectors, reducing image size, using image sprite etc.) which makes a website slow on Internet Explorer, because my website works fine on the others like FF, chrome etc. Is it the huge use of Javascript framework (ie. jQuery, extjs, prototype)? Is it because of the use of plugins based on JS framework? Should I use core javascript and remove the use of any js framework? Should I try to avoid using jQuery(document).ready()? in case of jQuery framework? Above some of the questions which I know and please answer the questions which I couldn't ask because of lesser knowledge about these. I need to make my website perform well on IE (6,7,8) also please suggest. Thanks

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• How to handle dependency files in a cross-platform manner?

  - by Brian Knoblauch

  I'm working on updating an old app. It has some dependency files that live in the same directory as the app. Obviously this broke when Windows Vista came out (since it violates the API and Vista/7 now enforce that (XP didn't)). Ideally, I'd like to avoid hardcoding anything into the app for just Windows. I can live with that if I have to though. I've already been down that path with pulling the APPDATA and LOCALAPPDATA environment variables, but that doesn't help any since they just give you the current user area... I need these to live somewhere accessible for all users, and I'd like to obey the Windows API expectations that they go into the all user appdata area. Suggestions?

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• c# .net framework subtracting time-span from date

  - by smkngspcmn

  I want to subtract a time-span from a date-time object. Date is 1983/5/1 13:0:0 (y/m/d-h:m:s) Time span is 2/4/28-2:51:0 (y/m/d-h:m:s) I can use the native DateTime and TimeSpan objects to do this, after converting years and months of the time-span to days (assuming a 30 day month and a ~364 day year). new DateTime(1981,5,1,13,0,0).Subtract(new TimeSpan(878,13,51,0)); With this i get the result: {12/4/1978 11:09:00 PM} But this is not exactly what i expected. If i do this manually (assuming a 30 day month) i get 1981/0/3-10:9:0 This is pretty close to what i'm after except i shouldn't get 0 for month and year should be 1980. So can someone please show me how i can do this manually and avoid getting a 0 month value? Also why do i get a completely different value when i use native classes?

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• Accessing php $_SESSION from python (wsgi) - is it possible?

  - by Bill Zimmerman

  Hi, I've got a python/WSGI app which needs to check to see if a user has logged on to a PHP web app. The problem is that the PHP app checks if a user has logged on by comparing a value in the $_SESSION variable to a value in the cookie from the user's browser. I would prefer to avoid changing the behavior of the php app if at all possible. My questions: Is there anyway I can access the session variables from within python? Where should I start to look? Are there any obvious security/performance issues I should be aware of when taking this approach?

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• Is it a good practice to create a reference to application context and use it anywhere?

  - by kknight

  I have to use context in many places of my code such as database operations, preference operations, etc. I don't want to pass in context for every method. Is it a good practice to create a reference to application context at the main Activity and use it anywhere such as database operations? So, I don't need some many context in method parameters, and the code can avoid position memory leak due to use of Activity Context. public class MainActivity extends Activity { public static Context s_appContext; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); s_appContext = this.getApplicationContext();

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• how to call a C++ dll from C# windows application project

  - by chathuradd

  I have created a dll in C++ using a Class Library project in Visual Studio. I need to call a method in the dll from a C# application. I got to know there are 2 approches. One is to add the dll project reference to C# project or use DllExport to export method. However when I tried in both ways it always gives the following error when the dll method is called in runtime. An unhandled exception of type 'System.BadImageFormatException' occurred in TestClient.exe Additional information: An attempt was made to load a program with an incorrect format. (Exception from HRESULT: 0x8007000B) Can i know how to avoid this problem ? Thanks in advance!

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• What programming languages do you consider indispensable in your experience?

  - by Federico Ramponi

  Each programming language comes with its concepts, best practices, libraries, tools, community, in one word: culture. Learning more than one programming language will make you a better programmer, for the more concepts you learn, the faster you will feel comfortable when the next language or technology will come. Mine, so far, are C, some C++, and Python, and many times I read that it would be worth learning LISP, for "the profound enlightenment experience you will have when you finally get it" (quoting Eric Raymond). My questions are: Which is the next one you would consider a good investment to learn? Of the many programming languages you have learnt and worked with, which ones do you consider to be an essential part of one's CS culture, and why? EDIT. Further question: is there any language you would sincerely advise to avoid as a waste of time? (The famous, and questionable, slatings in this letter from Dijkstra come to my mind.)

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• How to automatically check out a database file in a source controlled web application ?

  - by TheRHCP

  Hello, I am working on an ASP.NET web application, we are a small team (4 students) and we do not have access to a dedicated server to host the database instance. So for this web application we decided just to put the database file in the App_Data folder. The problem is that our project is source controled on TFS, so every time you open the solution and try to launch the web application, we get an expcetion saying that database is read-only. That is logical because the databse file is not automatically checked-out. Is there a workaround to avoid a manual check-out of the database file everytime we open the solution ? Thanks.

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• Use a function in a conditions hash

  - by Pierre

  Hi, I'm building a conditions hash to run a query but I'm having a problem with one specific case: conditions2 = ['extract(year from signature_date) = ?', params[:year].to_i] unless params[:year].blank? conditions[:country_id] = COUNTRIES.select{|c| c.geography_id == params[:geographies]} unless params[:geographies].blank? conditions[:category_id] = CATEGORY_CHILDREN[params[:categories].to_i] unless params[:categories].blank? conditions[:country_id] = params[:countries] unless params[:countries].blank? conditions['extract(year from signature_date)'] = params[:year].to_i unless params[:year].blank? But the last line breaks everything, as it gets interpreted as follows: AND ("negotiations"."extract(year from signature_date)" = 2010 Is there a way to avoid that "negotiations"." is prepended to my condition? thank you, P.

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• What does "static" mean in the context of declaring global template functions?

  - by smf68

  I know what static means in the context of declaring global non-template functions (see e.g. What is a "static" function?), which is useful if you write a helper function in a header that is included from several different locations and want to avoid "duplicate definition" errors. So my question is: What does static mean in the context of declaring global template functions? Please note that I'm specifically asking about global, non-member template functions that do not belong to a class. In other words, what is the difference between the following two: template <typename T> void foo(T t) { /* implementation of foo here */ } template <typename T> static void bar(T t) { /* implementation of bar here */ }

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• Fatal error: Cannot use string offset as an array

  - by learner

  Array ( [0] = Array ( [auth_id] = 1 [auth_section] = Client Data Base [auth_parent_id] = 0 [auth_admin] = 1 [sub] = Array ( [0] = Array ( [auth_id] = 2 [auth_section] = Client Contact [auth_parent_id] = 1 [auth_admin] = 1 ) ) ) [1] => Array ( [auth_id] => 6 [auth_section] => All Back Grounds [auth_parent_id] => 0 [auth_admin] => ,4 [sub] => Array ( [0] => Array ( [auth_id] => 7 [auth_section] => Edit Custom [auth_parent_id] => 6 [auth_admin] => 1 ) ) ) [2] => Array ( [auth_id] => 20 [auth_section] => Order Mail [auth_parent_id] => 0 [auth_admin] => 1 [sub] => ) } When I process the sub inner array it shows this error how can I avoid that :)

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• UITableView with contact image problems.

  - by prathumca

  As par my app requirement, I'm showing the contact images in a UITableView as shown below. ABRecordRef contact = [self getContact]; if(contact && ABPersonHasImageData(contact)) { UIImage *contactImage = [UIImage imageWithData:(NSData*)ABPersonCopyImageData(contact)]; callImage.image = contactImage; } I've two problems if I use the above code segment. Table Scrolling is too slow. If comment the above code, then UITable responds very fast. Memory Management. My app started using 25 - 30 MB of RAM. Is there any better way to avoid the above two problems?

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• Doctrine2: Filtering by ManToMany Association

  - by Shroder

  I want to retrieve a collection of objects based on what they are associated to. For example, by a category. This would be a Many to Many relationship. I've been able to achieve that with MEMBER OF, however I need to pass in an array of IDs, opposed to one at a time. I see there is an "IN ()", but it seems to require a subquery, which I would like to avoid. MEMBER OF example: SELECT o FROM Entity\Object1 o WHERE 'CATEGORY_CODE' MEMBER OF o.categories (Edit) This is what I would like to do, but perhaps I'm misunderstanding how entities work in DQL: SELECT o FROM Entity\Object1 o WHERE o.categories.Id IN (id, id, id)

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• Is the "message" of an exception culturally independent?

  - by Ray Hayes

  In an application I'm developing, I have the need to handle a socket-timeout differently from a general socket exception. The problem is that many different issues result in a SocketException and I need to know what the cause was. There is no inner exception reported, so the only information I have to work with is the message: "A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond" This question has a general and specific part: is it acceptable to write conditional logic based upon the textual representation of an exception? Is there a way to avoid needing exception handling? Example code below... try { IPEndPoint endPoint = null; client.Client.ReceiveTimeout = 1000; bytes = client.Receive(ref endPoint); } catch( SocketException se ) { if ( se.Message.Contains("did not properly respond after a period of time") ) { // Handle timeout differently.. } }

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• Status corresponding to Minimum value

  - by Lijo

  Hi Team, I am using SQL Server 2005. I have a table as given below. There can be multiple cancellations for each FundingID. I want to select the FundingCancellationReason corrersponding to minimum date for each funding. I wrote a query as follows. It is an SQL error 1) Could you please help me to avoid the SQL Error? 2) Is there any better logic to achieve the same? CREATE TABLE #FundingCancellation( [FundingCancellationID] INT IDENTITY(1,1) NOT NULL, [FundingID] INT , FundingCancellationDt SMALLDATETIME , FundingCancellationReason VARCHAR(50) ) SELECT FundingID, MIN(FundingCancellationDt), ( SELECT FundingCancellationReason FROM #FundingCancellation FC2 WHERE FC1.FundingID = FC2.FundingID AND FC2.FundingCancellationDt = MIN(FundingCancellationDt) ) [Reason Corresponding Minimum Date] FROM #FundingCancellation FC1 GROUP BY FundingID -- An aggregate may not appear in the WHERE clause unless it is in a subquery contained in a HAVING clause or a select list, and the column being aggregated is an outer reference. I have seen the similar approach working in a somewhat complex query. So I believe tehre will be a way to correct my query Thanks Lijo

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• How to match the word in jquery

  - by Mirage

  I have the image and i am fade in and fade out the image on click. But i want that if the same is present then it should not fadein/fadeout. My jquery code is switch(current_id) { case 'l1': $("#left_img img").fadeOut(500, function() { $(this).attr("src","rrr.gif").load( function() { $(this).fadeIn(500); }); }); break; case 'l3': $("#left_img img").fadeOut(500, function() { $(this).attr("src","cc1.gif").load( function() { $(this).fadeIn(500); }); }); break; If i click on link 1 then image A appears with fade effect. but if i click again link 1 agan , then again i see fade effect . Is there any way i can avoid that if same link is clicked again

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• Prevent Erroneous Property Assignment

  - by Gordon

  Porting android applications to iphone applications always gives me the following pattern that I accidentally create: - (void) myFunc:(id)prop { self.property = property; } Which instead should be: - (void) myFunc:(id)prop { self.property = prop; } This always causes my program to quietly break because property gets reset to its existing value rather than being set to the new value, 'prop'. I cannot name the parameter 'prop' to 'property' since the compile complains that the parameter masks the instance variables visibility. Is there a good way to avoid this situation? There are no compiler warnings. Is there a way to make xcode prevent this? I cannot see very many situations where you would set a property to the value of its underlying instance variable (maybe to trigger a KVO binding?), but I don't see myself doing that in majority of cases. I understand the above code is synthetic and should be done with @synthesize, but I am just using it as a simplified example to illustrate my point.

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• Jquery Accordion and multiple slideshows

  - by Dipesh Parmar

  I've been using a lot of slideshows recently on my sites and one thing thats puzzled me is using more than one slideshow per page. I'm currently working on my own site, experimenting with Jquery Accordion. I've managed to adopt a very simple javascript slideshow, see below: http://dvpwebdesign.com/test/accordion/blank.html However i'm unable to either incorporate or use a different multiple slideshow plugin. I dont need slideshow navigation, so the The Cycle plugin works really well and i know you can use multiple slideshows. But if i either use Cycle alongside the current javascript slideshow, or only use the Cycle slideshow to avoid any possible conflict, the Accordion menu stops working. I just cant see what i am doing wrong, can anyone help?

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• C# - Why can't I enforce derived classes to have parameterless constructors?

  - by FrisbeeBen

  I am trying to do the following: public class foo<T> where T : bar, new { _t = new T(); private T _t; } public abstract class bar { public abstract void someMethod(); // Some implementation } public class baz : bar { public overide someMethod(){//Implementation} } And I am attempting to use it as follows: foo<baz> fooObject = new foo<baz>(); And I get an error explaining that 'T' must be a non-abstract type with a public parameterless constructor in order to use it as parameter 'T' in the generic type or method. I fully understand why this must be, and also understand that I could pass a pre-initialized object of type 'T' in as a constructor argument to avoid having to 'new' it, but is there any way around this? any way to enforce classes that derive from 'bar' to supply parameterless constructors?

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• database row/ record pointers

  - by David

  Hi I don't know the correct words for what I'm trying to find out about and as such having a hard time googling. I want to know whether its possible with databases (technology independent but would be interested to hear whether its possible with Oracle, MySQL and Postgres) to point to specific rows instead of executing my query again. So I might initially execute a query find some rows of interest and then wish to avoid searching for them again by having a list of pointers or some other metadata which indicates the location on a database which I can go to straight away the next time I want those results. I realise there is caching on databases, but I want to keep these "pointers" else where and as such caching doesn't ultimately solve this problem. Is this just an index and I store the index and look up by this? most of my current tables don't have indexes and I don't want the speed decrease that sometimes comes with indexes. So whats the magic term I've been trying to put into google? Cheers

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• Sharing base object with inheritance

  - by max

  I have class Base. I'd like to extend its functionality in a class Derived. I was planning to write: class Derived(Base): def __init__(self, base_arg1, base_arg2, derived_arg1, derived_arg2): super().__init__(base_arg1, base_arg2) # ... def derived_method1(self): # ... Sometimes I already have a Base instance, and I want to create a Derived instance based on it, i.e., a Derived instance that shares the Base object (doesn't re-create it from scratch). I thought I could write a static method to do that: b = Base(arg1, arg2) # very large object, expensive to create or copy d = Derived.from_base(b, derived_arg1, derived_arg2) # reuses existing b object but it seems impossible. Either I'm missing a way to make this work, or (more likely) I'm missing a very big reason why it can't be allowed to work. Can someone explain which one it is? [Of course, if I used composition rather than inheritance, this would all be easy to do. But I was hoping to avoid the delegation of all the Base methods to Derived through __getattr__.]

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• Online payment service recommendation?

  - by Shadowman

  We're currently in the process of looking for an online payment service that will allow us to accept credit cards, etc. However, our business model also involves revenue sharing in a model similar to that of iTunes. That is, content creators will be able to sell content through our site and we take a small percentage of the revenue. Can anyone recommend an online payment service that supports this model? We're also interested in: Accept all major credit cards Being able to do international transactions in the appropriate local currency Recurring transactions (monthly, yearly, etc.) Additionally, if the service provided a Java API for integration or the ability to broker PayPal transactions that would be an added bonus. I know Amazon provides a hosted payment service, but I'd prefer not to require all of our customers to have an Amazon account. That provides an additional barrier to entry that we'd prefer to avoid. I'd appreciate any recommendations you can provide!

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• Multivalue parametres in SSRS- display in the report

  - by pfeffer

  I just started working with SSRS, so this question might seem silly. Anyway, for now I'm trying to avoid multi-valued parameters, because I want my parameters to be able to be NULL. So I'm just passing a comma-separated string of ID values to my stored procedure, and everything works. The problem I encountered is that I want to display the actual values, not IDs, in the report, so that users can see, what filter was used. If that were a multi-valued parameter, I would simply use JOIN function, but now I am out of ideas and would really appreciate some help. Thanks!

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