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  • Optional Member Objects

    - by David Relihan
    Okay, so you have a load of methods sprinkled around your systems main class. So you do the right thing and refactor by creating a new class and perform move method(s) into a new class. The new class has a single responsibility and all is right with the world again: class Feature { public: Feature(){}; void doSomething(); void doSomething1(); void doSomething2(); }; So now your original class has a member variable of type object: Feature _feature; Which you will call in the main class. Now if you do this many times, you will have many member-objects in your main class. Now these features may or not be required based on configuration so in a way it's costly having all these objects that may or not be needed. Can anyone suggest a way of improving this? At the moment I plan to test in the newly created class if the feature is enabled - so the when a call is made to method I will return if it is not enabled. I could have a pointer to the object and then only call new if feature is enabled - but this means I will have to test before I call a method on it which would be potentially dangerous and not very readable. Would having an auto_ptr to the object improve things: auto_ptr<Feature> feature; Or am I still paying the cost of object invokation even though the object may\or may not be required. BTW - I don't think this is premeature optimisation - I just want to consider the possibilites.

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  • How do I delete a file from depot, but leave local copy in tact?

    - by Gary
    I'm trying to learn Perforce and want to delete a file from the depot(easy to do with p4 delete, p4 submit), but that deletes it from the client machine dir structure as well. I want to keep my local file in my directory intact. The only way I can see to do this would be to move it out of the hierarchy that is under Perforce control before deleting. I was able to get my file back by syncing an earlier version. Maybe I set up my client workspace wrong? Or am I misunderstanding a fundamental concept of source control? The client workspace is /home/user and I did it this way so I could add any file under my home directory without getting an error about the file not being under client's root. FYI - Linux client and server running P4D/LINUX26X86/2009.1/222893 (2009/11/12) Any advice appreciated. Thanks.

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  • How Can I Populate Default Form Data with a ManyToMany Field?

    - by b14ck
    Ok, I've been crawling google and Django documentation for over 2 hours now (as well as the IRC channel on freenode), and haven't been able to figure this one out. Basically, I have a model called Room, which is displayed below: class Room(models.Model): """ A `Partyline` room. Rooms on the `Partyline`s are like mini-chatrooms. Each room has a variable amount of `Caller`s, and usually a moderator of some sort. Each `Partyline` has many rooms, and it is common for `Caller`s to join multiple rooms over the duration of their call. """ LIVE = 0 PRIVATE = 1 ONE_ON_ONE = 2 UNCENSORED = 3 BULLETIN_BOARD = 4 CHILL = 5 PHONE_BOOTH = 6 TYPE_CHOICES = ( ('LR', 'Live Room'), ('PR', 'Private Room'), ('UR', 'Uncensored Room'), ) type = models.CharField('Room Type', max_length=2, choices=TYPE_CHOICES) number = models.IntegerField('Room Number') partyline = models.ForeignKey(Partyline) owner = models.ForeignKey(User, blank=True, null=True) bans = models.ManyToManyField(Caller, blank=True, null=True) def __unicode__(self): return "%s - %s %d" % (self.partyline.name, self.type, self.number) I've also got a forms.py which has the following ModelForm to represent my Room model: from django.forms import ModelForm from partyline_portal.rooms.models import Room class RoomForm(ModelForm): class Meta: model = Room I'm creating a view which allows administrators to edit a given Room object. Here's my view (so far): def edit_room(request, id=None): """ Edit various attributes of a specific `Room`. Room owners do not have access to this page. They cannot edit the attributes of the `Room`(s) that they control. """ room = get_object_or_404(Room, id=id) if not room.is_owner(request.user): return HttpResponseForbidden('Forbidden.') if is_user_type(request.user, ['admin']): form_type = RoomForm elif is_user_type(request.user, ['lm']): form_type = LineManagerEditRoomForm elif is_user_type(request.user, ['lo']): form_type = LineOwnerEditRoomForm if request.method == 'POST': form = form_type(request.POST, instance=room) if form.is_valid(): if 'owner' in form.cleaned_data: room.owner = form.cleaned_data['owner'] room.save() else: defaults = {'type': room.type, 'number': room.number, 'partyline': room.partyline.id} if room.owner: defaults['owner'] = room.owner.id if room.bans: defaults['bans'] = room.bans.all() ### this does not work properly! form = form_type(defaults, instance=room) variables = RequestContext(request, {'form': form, 'room': room}) return render_to_response('portal/rooms/edit.html', variables) Now, this view works fine when I view the page. It shows all of the form attributes, and all of the default values are filled in (when users do a GET)... EXCEPT for the default values for the ManyToMany field 'bans'. Basically, if an admins clicks on a Room object to edit, the page they go to will show all of the Rooms default values except for the 'bans'. No matter what I do, I can't find a way to get Django to display the currently 'banned users' for the Room object. Here is the line of code that needs to be changed (from the view): defaults = {'type': room.type, 'number': room.number, 'partyline': room.partyline.id} if room.owner: defaults['owner'] = room.owner.id if room.bans: defaults['bans'] = room.bans.all() ### this does not work properly! There must be some other syntax I have to use to specify the default value for the 'bans' field. I've really been pulling my hair out on this one, and would definitely appreciate some help. Thanks!

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  • How much user data should be required to grant a password reset?

    - by Andrew Heath
    I'm looking to add password-reset functionality to my site and have been browsing the numerous threads discussing various aspects of that issue here on SO. One thing I haven't really seen clarified is how much information to require from the user for confirmation before sending out the reset email. is email alone enough? email + account username? email + account username + some other identifying value all accounts must input? I don't want my site to seem like an old wrinkly nun with a ruler, but I don't want people to be able to abuse the password reset system willy-nilly. Suggestions?

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  • trending topics example for a rails app

    - by Gautam
    Hi, I am new to ruby on rails. I want to build an RSS feed aggregator. How do I find out the trending topics from the stream of data[titles] from various RSS feeds. Could you help me how to achieve this?? Looking forward for your help Thanks in advance Gautam

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  • Views performance in MySQL

    - by Gianluca Bargelli
    I am currently writing my truly first PHP Application and i would like to know how to project/design/implement MySQL Views properly; In my particular case User data is spread across several tables (as a consequence of Database Normalization) and i was thinking to use a View to group data into one large table: CREATE VIEW `Users_Merged` ( name, surname, email, phone, role ) AS ( SELECT name, surname, email, phone, 'Customer' FROM `Customer` ) UNION ( SELECT name, surname, email, tel, 'Admin' FROM `Administrator` ) UNION ( SELECT name, surname, email, tel, 'Manager' FROM `manager` ); This way i can use the View's data from the PHP app easily but i don't really know how much this can affect performance. For example: SELECT * from `Users_Merged` WHERE role = 'Admin'; Is the right way to filter view's data or should i filter BEFORE creating the view itself? (I need this to have a list of users and the functionality to filter them by role).

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  • Strategy Pattern with Type Reflection affecting Performances ?

    - by Aurélien Ribon
    Hello ! I am building graphs. A graph consists of nodes linked each other with links (indeed my dear). In order to assign a given behavior to each node, I implemented the strategy pattern. class Node { public BaseNodeBehavior Behavior {get; set;} } As a result, in many parts of the application, I am extensively using type reflection to know which behavior a node is. if (node.Behavior is NodeDataOutputBehavior) workOnOutputNode(node) .... My graph can get thousands of nodes. Is type reflection greatly affecting performances ? Should I use something else than the strategy pattern ? I'm using strategy because I need behavior inheritance. For example, basically, a behavior can be Data or Operator, a Data behavior can IO, Const or Intermediate and finally an IO behavior can be Input or Output. So if I use an enumeration, I wont be able to test for a node behavior to be of data kind, I will need to test it to be [Input, Output, Const or Intermediate]. And if later I want to add another behavior of Data kind, I'm screwed, every data-testing method will need to be changed.

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  • Are GUIDs the ultimate ID?

    - by mafutrct
    I noticed some people don't bother having the usual incremented number as ID but instead simply generate a GUID. The advantages include: Quick and easy No need to keep track of previous IDs Guaranteed to be unique even across machines without knowledge of each other Some disadvantages are: Possibly performance bottleneck Uses a large number of bytes My understanding is that using a GUID is beneficial in most cases, except if optimization for time or space is an issue. Did I miss something? Or do you agree with this idea?

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  • Rails Controller

    - by Steve
    Hi...In Rails, is it ok to define logic in a controller with a model. For example, take there is an User Model, which is good design. 1)Leaving the UserModel with the CRUD models and moving all the other User Specific actions to a separate controller or 2)Add the user specific actions to the same UserModels Thanks :)

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  • What is the correct way to unit test areas around exceptions

    - by Codek
    Hi, Looking at our code coverage of our unit tests we're quite high. But the last few % is tricky because a lot of them are catching things like database exceptions - which in normal circumstances just dont happen. For example the code prevents fields being too long etc, so the only possible database exceptions are if the DB is broken/down, or if the schema is changed under our feet. So is the only way to Mock the objects such that the exception can be thrown? That seems a little bit pointless. Perhaps it's better to just accept not getting 100% code coverage? Thanks, Dan

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  • Disposing underlying object from finalizer in an immutable object

    - by Juan Luis Soldi
    I'm trying to wrap around Awesomium and make it look to the rest of my code as close as possible to NET's WebBrowser since this is for an existing application that already uses the WebBrowser. In this library, there is a class called JSObject which represents a javascript object. You can get one of this, for instance, by calling the ExecuteJavascriptWithResult method of the WebView class. If you'd call it like myWebView.ExecuteJavascriptWithResult("document", string.Empty).ToObject(), then you'd get a JSObject that represents the document. I'm writing an immutable class (it's only field is a readonly JSObject object) called JSObjectWrap that wraps around JSObject which I want to use as base class for other classes that would emulate .NET classes such as HtmlElement and HtmlDocument. Now, these classes don't implement Dispose, but JSObject does. What I first thought was to call the underlying JSObject's Dispose method in my JSObjectWrap's finalizer (instead of having JSObjectWrap implement Dispose) so that the rest of my code can stay the way it is (instead of having to add using's everywhere and make sure every JSObjectWrap is being properly disposed). But I just realized if more than two JSObjectWrap's have the same underlying JSObject and one of them gets finalized this will mess up the other JSObjectWrap. So now I'm thinking maybe I should keep a static Dictionary of JSObjects and keep count of how many of each of them are being referenced by a JSObjectWrap but this sounds messy and I think could cause major performance issues. Since this sounds to me like a common pattern I wonder if anyone else has a better idea.

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  • Passing data structures to different threads

    - by Robb
    I have an application that will be spawning multiple threads. However, I feel there might be an issue with threads accessing data that they shouldn't be. I'm relatively new to threading so bare with me. Here is the structure of the threaded application (sorry for the crudeness): MainThread / \ / \ / \ Thread A Thread B / \ / \ / \ / \ / \ / \ Thread A_1 Thread A_2 Thread B_1 Thread B_2 Under each lettered thread (which could be many), there will only be two threads and they are fired of sequentially. The issue i'm having is I'm not entirely sure how to pass in a datastructure into these threads. So, the datastructure is created in MainThread, will be modified in the lettered thread (Thread A, etc) specific to that thread and then a member variable from that datastructure is sent to Letter_Numbered threads. Currently, the lettered thread class has a member variable and when the class is constructed, the datastructure from mainthread is passed in by reference, invoking the copy constructor so the lettered thread has it's own copy to play with. The lettered_numbered thread simply takes in a string variable from the data structure within the lettered thread. My question is, is this accceptable? Is there a much better way to ensure each lettered thread gets its own data structure to play with? Sorry for the somewhat poor explanation, please leave comments and i'll try to clarify.

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  • How do you energize yourself when working alone on a project?

    - by Stephane
    I am working in an environment with a very small team (3 developers only) and each of us have been assigned a different project, without counting support tasks. I know this is a bad business practice and that we should all work on a single project at a time, and then move on to the next one (Already explained to the management on how much it sucks). So don't answer me that we should work all together on one project at a time. Energizing the work when in a team is mostly pair programming we did that when less project were thrown at us and that was great. What I would like to know is how you energize your work when working alone on a project. Do you follow any particular practice?

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  • Why is the software world full of status codes?

    - by David V McKay
    Why did programmers ever start using status codes? I mean, I guess I could imagine this might be useful back in the days when a text string was an expensive resource. WAYYY back then. But even after we had megabytes of memory to work with, we continued to use them. What possible advantage could there be for obfuscating the meaning of an error message or status message behind a status code?

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  • System.Drawing.Image for Images in Business Objects?

    - by Mudu
    Hi Folks I'd like to store an image in a business object. In MSDN I saw that the System.Drawing-namespace provides lots of GDI+-features, etc. Is it okay to store an Image in an System.Drawing.Image class in business layer (which is a class library "only"), and thus including a reference to System.Drawing too? I slightly feel just kind of bad doing that, 'cause it seems like I have UI-specific references in business code. Moreover, the code could become unnecessarily platform-dependant (though this is only a problem in theory, because we do not develop for multiple platforms). If it isn't right that way, which type would fit best? Thank you for any response! Matthias

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  • desing pattern for related inputs

    - by curiousMo
    My question is a design question : let's say i have a data entry web page with 4 drop down lists, each depending on the previous one, and a bunch of text boxes. country (ddl), state (ddl), city (ddl), boro (ddl), address (txtBox), zipcode(txtbox). and an object that represents a datarow with a value for each. naturally the country, state, city and boro values will be values of primary keys of some lookup tables. when the user chooses to edits that record, i would load it from database and load it into the page. the issue that I have is how to streamline loading the ddls. i have some code that would grab the object, look thru its values and move them to their corresponding input controls in one shot. but in this case i will have to load possible values of country, then assign values, then load values of state, then assign value ans so on. I guess i am looking for an elegant solution. i am using asp.net, but i think it is irrelevant to the question. i am looking more into a design pattern. thanks

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  • isPostBack as Query Parameter

    - by Steven
    I created an ASPX page with search controls to the left bound as controls for an AccessDataSource. I want the data grid to be blank on the first calling of the page, but show the results for subsequent page loads. I plan to achieve this by putting [pFirstRun] = False as my first WHERE condition with the parameter pFirstRun tied to the value isPostBack. How do I achieve this? Alternatively, is there a better way to achieve this goal?

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  • Best Practice For Referencing an External Module In a Java Project

    - by Greg Harman
    I have a Java project that expects external modules to be registered with it. These modules: Implement a particular interface in the main project Are packaged into a uni-jar (along with any dependencies) Contain some human-readable meta-information (like the module name). My main project needs to be able to load at runtime (e.g. using its own classloader) any of these external modules. My question is: what's the best way of registering these modules with the main project (I'd prefer to keep this vanilla Java, and not use any third-party frameworks/libraries for this isolated issue)? My current solution is to keep a single .properties file in the main project with key=name, value=classhuman-readable-name (or coordinate two .properties files in order to avoid the delimiter parsing). At runtime, the main project loads in the .properties file and uses any entries it finds to drive the classloader. This feels hokey to me. Is there a better way to this?

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  • REST: Should I redirect to the version URL of an entity?

    - by sfussenegger
    I am currently working on a REST service. This service has an entity which has different versions, similar to Wikipedia articles. Now I'm wondering what I should return if for GET /article/4711 Should I use a (temporary) redirect to the current version, e.g. GET /article/4711/version/7 Or should I return the current version directly? Using redirects would considerably simplify HTTP caching (using Last-Modified) but has the disadvantages a redirect has (extra request, 'harder' to implement). Therefore I'm not sure whether this is good practice though. Any suggestions, advise, or experiences to share? (btw: ever tried search for "REST Version"? Everything you get is about the version of the API rather than entities. So please bear with me if this is a duplicate.)

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  • Constructor versus setter injection

    - by Chris
    Hi, I'm currently designing an API where I wish to allow configuration via a variety of methods. One method is via an XML configuration schema and another method is through an API that I wish to play nicely with Spring. My XML schema parsing code was previously hidden and therefore the only concern was for it to work but now I wish to build a public API and I'm quite concerned about best-practice. It seems that many favor javabean type PoJo's with default zero parameter constructors and then setter injection. The problem I am trying to tackle is that some setter methods implementations are dependent on other setter methods being called before them in sequence. I could write anal setters that will tolerate themselves being called in many orders but that will not solve the problem of a user forgetting to set the appropriate setter and therefore the bean being in an incomplete state. The only solution I can think of is to forget about the objects being 'beans' and enforce the required parameters via constructor injection. An example of this is in the default setting of the id of a component based on the id of the parent components. My Interface public interface IMyIdentityInterface { public String getId(); /* A null value should create a unique meaningful default */ public void setId(String id); public IMyIdentityInterface getParent(); public void setParent(IMyIdentityInterface parent); } Base Implementation of interface: public abstract class MyIdentityBaseClass implements IMyIdentityInterface { private String _id; private IMyIdentityInterface _parent; public MyIdentityBaseClass () {} @Override public String getId() { return _id; } /** * If the id is null, then use the id of the parent component * appended with a lower-cased simple name of the current impl * class along with a counter suffix to enforce uniqueness */ @Override public void setId(String id) { if (id == null) { IMyIdentityInterface parent = getParent(); if (parent == null) { // this may be the top level component or it may be that // the user called setId() before setParent(..) } else { _id = Helpers.makeIdFromParent(parent,getClass()); } } else { _id = id; } } @Override public IMyIdentityInterface getParent() { return _parent; } @Override public void setParent(IMyIdentityInterface parent) { _parent = parent; } } Every component in the framework will have a parent except for the top level component. Using the setter type of injection, then the setters will have different behavior based on the order of the calling of the setters. In this case, would you agree, that a constructor taking a reference to the parent is better and dropping the parent setter method from the interface entirely? Is it considered bad practice if I wish to be able to configure these components using an IoC container? Chris

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  • Is it OK to reference 'this' when initializing a field?

    - by parxier
    Is it OK to reference this when initializing a field? public class MainClass { private SomeFieldClass field = new SomeFieldClass(this); public MainClass() {} } Or is it better to do that in constructor? public class MainClass { private SomeFieldClass field; public MainClass() { this.field = new SomeFieldClass(this); } } What is the best practice? I believe first option is better for unit testing and dependency injection. Are there any problems with it?

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  • How doe we name test methods where we are checking for more than one condition?

    - by Sandbox
    I follow the technique specified in Roy Osherove's The Art Of Unit Testing book while naming test methods - MethodName_Scenario_Expectation. It suits perfectly well for my 'unit' tests. But,for tests that I write in 'controller' or 'coordinator' class, there isn't necessarily a method which I want to test. For these tests, I generate multiple conditions which make up one scenario and then I verify the expectation. For example, I may set some properties on different instances, generate an event and then verify that my expectations from controller/coordinator is being met. Now, my controller handles events using a private event handler. Here my scenario is that, I set some properties, say 3 condition1,condition2 and condition3 Also, my scenario includes an event is raised I don't have a method name as my event handler is private. How do I name such a test method?

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