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  • Good input validation loop using cin - C++

    - by Alex
    Hi there, I'm in my second OOP class, and my first class was taught in C#, so I'm new to C++ and currently I am practicing input validation using cin. So here's my question: Is this loop I constructed a pretty good way of validating input? Or is there a more common/accepted way of doing it? Thanks! Code: int taxableIncome; int error; // input validation loop do { error = 0; cout << "Please enter in your taxable income: "; cin >> taxableIncome; if (cin.fail()) { cout << "Please enter a valid integer" << endl; error = 1; cin.clear(); cin.ignore(80, '\n'); } }while(error == 1);

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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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  • Is there a recommended way to use the Observer pattern in MVP using GWT?

    - by Tomislav Nakic-Alfirevic
    I am thinking about implementing a user interface according to the MVP pattern using GWT, but have doubts about how to proceed. These are (some of) my goals: - the presenter knows nothing about the UI technology (i.e. uses nothing from com.google.*) - the view knows nothing about the model or the presenter - the model knows nothing of the view or the presenter (...obviously) I would place an interface between the view and the presenter and use the Observer pattern to decouple the two: the view generates events and the presenter gets notified. What confuses me is that java.util.Observer and java.util.Observable are not supported in GWT. This suggests that what I'm doing is not the recommended way to do it, as far as GWT is concerned, which leads me to my questions: what is the recommended way to implement MVP using GWT, specifically with the above goals in mind? How would you do it?

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  • Is it considered a good/bad practice to configure tomcat for deploying certain apps?

    - by Roman
    Disclaimer: I've never used technique which is described below. That's why there may occur some mistakes or misunderstandings in its description. I heard that some teams (developers) use 'pre-configured' tomcat. As I understand they add different jars to tomcat \lib folder and do something else. Once I've read something about recompilation (or reassembly?) of tomcat for certain needs. Just yesterday I heard a dialog where one developer sayd that his team-mates were not able to deploy the project until he would give them configured tomcat version. So, I wonder, what is it all about and why do they do it? What benefits can they gain from that?

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  • CSS Negative margins for positioning.

    - by Kyle Sevenoaks
    Is it ok to use negative margins for positioning? I have a lot in my current site and feel like it's not such a stable way to position things. I usually suggest to use them too. For example I have a checkout page with three divs on top of each other <div class="A"> header </div> <div class="B"> content </div> <div class="C"> footer </div> (A, B and C), which are meant to sit on top of each other, to appear attached. I did this using: .B { margin-top: -20px; } On div B, to meet the bottom of div A. Is this good practice or shall I re-code using top and left?

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  • How to avoid having very large objects with Domain Driven Design

    - by Pablojim
    We are following Domain Driven Design for the implementation of a large website. However by putting the behaviour on the domain objects we are ending up with some very large classes. For example on our WebsiteUser object, we have many many methods - e.g. dealing with passwords, order history, refunds, customer segmentation. All of these methods are directly related to the user. Many of these methods delegate internally to other child object but this still results in some very large classes. I'm keen to avoid exposing lots of child objects e.g. user.getOrderHistory().getLatestOrder(). What other strategies can be used to avoid this problems?

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  • How to build a JSON response by combining @foo.to_json(options) and @bars.to_json(options) in Rails

    - by smotchkkiss
    First, the desired result I have User and Item models. I'd like to build a JSON response that looks like this: { "user": {"username":"Bob!","foo":"whatever","bar":"hello!"}, "items": [ {"id":1, "name":"one", "zim":"planet", "gir":"earth"}, {"id":2, "name":"two", "zim":"planet", "gir":"mars"} ] } However, my User and Item model have more attributes than just those. I found a way to get this to work, but beware, it's not pretty... Please help... My hacks home_controller.rb class HomeController < ApplicationController def observe respond_to do |format| format.js { render :json => Observation.new(current_user, @items).to_json } end end end observation.rb # NOTE: this is not a subclass of ActiveRecord::Base # this class just serves as a container to aggregate all "observable" objects class Observation attr_accessor :user, :items def initialize(user, items) self.user = user self.items = items end # The JSON needs to be decoded before it's sent to the `to_json` method in the home_controller otherwise the JSON will be escaped... # What a mess! def to_json { :user => ActiveSupport::JSON.decode(user.to_json(:only => :username, :methods => [:foo, :bar])), :items => ActiveSupport::JSON.decode(auctions.to_json(:only => [:id, :name], :methods => [:zim, :gir])) } end end

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  • Displaying an NSString on a Custom View

    - by ilovetacos
    I have an interface that has an NSTextField, NSButton, and an NSView. When I type something in the textfield and press the button, I want the text to be drawn in the NSView. So far I have everything connected and working, except for the view. How can I connect the text and the view so that every time I press the button, the text is drawn to the view?

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  • Using DTOs and BOs

    - by ryanzec
    One area of question for me about DTOs/BOs is about when to pass/return the DTOs and when to pass/return the BOs. My gut reaction tells me to always map NHibernate to the DTOs, not BOs, and always pass/return the DTOs. Then whenever I needed to perform business logic, I would convert my DTO into a BO. The way I would do this is that my BO would have a have a constructor that takes a parameter that is the type of my interface (that defines the required fields/properties) that both my DTO and BO implement as the only argument. Then I would be able to create my BO by passing it the DTO in the constructor (since both with implement the same interface, they both with have the same properties) and then be able to perform my business logic with that BO. I would then also have a way to convert a BO to a DTO. However, I have also seen where people seem to only work with BOs and only work with DTOs in the background where to the user, it looks like there are no DTOs. What benefits/downfalls are there with this architecture vs always using BO's? Should I always being passing/returning either DTOs or BOs or mix and match (seems like mixing and matching could get confusing)?

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  • Best practice - When to evaluate conditionals of function execution

    - by Tesserex
    If I have a function called from a few places, and it requires some condition to be met for anything it does to execute, where should that condition be checked? In my case, it's for drawing - if the mouse button is held down, then execute the drawing logic (this is being done in the mouse movement handler for when you drag.) Option one says put it in the function so that it's guaranteed to be checked. Abstracted, if you will. public function Foo() { DoThing(); } private function DoThing() { if (!condition) return; // do stuff } The problem I have with this is that when reading the code of Foo, which may be far away from DoThing, it looks like a bug. The first thought is that the condition isn't being checked. Option two, then, is to check before calling. public function Foo() { if (condition) DoThing(); } This reads better, but now you have to worry about checking from everywhere you call it. Option three is to rename the function to be more descriptive. public function Foo() { DoThingOnlyIfCondition(); } private function DoThingOnlyIfCondition() { if (!condition) return; // do stuff } Is this the "correct" solution? Or is this going a bit too far? I feel like if everything were like this function names would start to duplicate their code. About this being subjective: of course it is, and there may not be a right answer, but I think it's still perfectly at home here. Getting advice from better programmers than I is the second best way to learn. Subjective questions are exactly the kind of thing Google can't answer.

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  • Best practice for installing python modules from an arbitrary VCS repository

    - by fmark
    I'm newish to the python ecosystem, and have a question about module editing. I use a bunch of third-party modules, distributed on PyPi. Coming from a C and Java background, I love the ease of easy_install <whatever>. This is a new, wonderful world, but the model breaks down when I want to edit the newly installed module for two reasons: The egg files may be stored in a folder or archive somewhere crazy on the file system. Using an egg seems to preclude using the version control system of the originating project, just as using a debian package precludes development from an originating VCS repository. What is the best practice for installing modules from an arbitrary VCS repository? I want to be able to continue to import foomodule in other scripts.

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  • are there any negative implications of sourcing a javascript file that does not actually exist?

    - by dreftymac
    If you do script src="/path/to/nonexistent/file.js" in an HTML file and call that in a browser, and there are no dependencies or resources anywhere else in the HTML file that expect the file or code therein to actually exist, is there anything inherently bad-practice about doing this? Yes, it is an odd question. The rationale is the developer is dealing with a CMS that allows custom (self-contained) javascript files to be provided in certain circumstances. The problem is the CMS is not very flexible when it comes to creating conditional includes for javascript. Therefore it is easier to just make references to the self-contained js files regardless of whether they are actually at the specified path. Since no errors are displayed to the user, should this practice be considered a viable option?

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  • Pattern for managing reference count and object life

    - by Gopalakrishnan Subramani
    We have a serial port which is connected to hundreds of physical devices on the same wire. We have protocols like Modbus and Hart to handle the request and response between the application and devices. The question is related to managing the reference count of the channel. When no device is using the channel, the channel should be closed. public class SerialPortChannel { int refCount = 0; public void AddReference() { refCount++; } public void ReleaseReference() { refCount--; if (refCount <= 0) this.ReleasePort(); //This close the serial port } } For each device connected, we create a object for the device like device = new Device(); device.Attach(channel); //this calls channel.AddReference() When the device disconnect, device.Detach(channel); //this calls channel.ReleaseReference() I am not convinced by the reference count model. Are there any better way to handle this problem in .NET World?

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  • To log in stored procedures?

    - by hgulyan
    If you have a long running SP, do you log somehow it's actions or just wait for this message? "Command(s) completed successfully." I assume, that there can be plenty solutions on this subject, but is there any best practice - a simple solution that is frequently used?

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  • Naming convention for utility classes in Java

    - by Zarjay
    When writing utility classes in Java, what are some good guidelines to follow? Should packges be "util" or "utils"? Is it ClassUtil or ClassUtils? When is a class a "Helper" or a "Utility"? Utility or Utilities? Or do you use a mixture of them? The standard Java library uses both Utils and Utilities: javax.swing.Utilities javax.print.attribute.AttributeSetUtilities javax.swing.plaf.basic.BasicGraphicsUtils Apache uses a variety of Util and Utils, although mostly Utils: org.apache.commons.modeler.util.DomUtil org.apache.commons.modeler.util.IntrospectionUtils org.apache.commons.io.FileSystemUtils org.apache.lucene.wordnet.AnalyzerUtil org.apache.lucene.util.ArrayUtil org.apache.lucene.xmlparser.DOMUtils Spring uses a lot of Helper and Utils classes: org.springframework.web.util.UrlPathHelper org.springframework.core.ReflectiveVisitorHelper org.springframework.core.NestedExceptionUtils org.springframework.util.NumberUtils So, how do you name your utility classes?

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  • How build my own Application Setting

    - by adisembiring
    I want to build a ApplicationSetting for my application. The ApplicationSetting can be stored in a properties file or in a database table. The settings are stored in key-value pairs. E.g. ftp.host = blade ftp.username = dummy ftp.pass = pass content.row_pagination = 20 content.title = How to train your dragon. I have designed it as follows: Application settings reader: interface IApplicationSettingReader { read(); } DatabaseApplicationSettingReader { dao appSettingDao; AppSettings read() { List<AppSettingEntity> listEntity = appSettingsDao.findAll(); Map<String, String> map = new HaspMap<String, String>(); foreach (AppSettingEntity entity : listEntity) { map.put(entity.getConfigName(), entity.getConfigValue()); } return new AppSettings(map); } } DatabaseApplicationSettingReader { dao appSettingDao; AppSettings read() { //read from some properties file return new AppSettings(map); } } Application settings class: AppSettings { private static AppSettings instance; private Map map; Public AppSettings(Map map) { this.map = map; } public static AppSettings getInstance() { if (instance == null) { throw new RuntimeException("Object not configure yet"); } return instance; } public static configure(IApplicationSettingReader reader) { instance = reader.read(); } public String getFtpSetting(String param) { return map.get("ftp." + param); } public String getContentSetting(String param) { return map.get("content." + param); } } Test class: AppSettingsTest { IApplicationSettingReader reader; @Before public void setUp() throws Exception { reader = new DatabaseApplicationSettingReader(); } @Test public void getContentSetting_should_get_content_title() { AppSettings.configure(reader); Instance settings = AppSettings.getInstance(); String title = settings.getContentSetting("title"); assertNotNull(title); Sysout(title); } } My questions are: Can you give your opinion about my code, is there something wrong? I configure my application setting once, while the application start, I configure the application setting with appropriate reader (DbReader or PropertiesReader), I make it singleton. The problem is, when some user edit the database or file directly to database or file, I can't get the changed values. Now, I want to implement something like ApplicationSettingChangeListener. So if the data changes, I will refresh my application settings. Do you have any suggestions how this can be implemented?

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  • Is it better to use List or Collection?

    - by Vivin Paliath
    I have an object that stores some data in a list. The implementation could change later, and I don't want to expose the internal implementation to the end user. However, the user must have the ability to modify and access this collection of data. Currently I have something like this: public List<SomeDataType> getData() { return this.data; } public void setData(List<SomeDataType> data) { this.data = data; } Does this mean that I have allowed the internal implementation details to leak out? Should I be doing this instead? public Collection<SomeDataType> getData() { return this.data; } public void setData(Collection<SomeDataType> data) { this.data = new ArrayList<SomeDataType>(data); }

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  • Best Practice for Utilities Class?

    - by Sonny Boy
    Hey all, We currently have a utilities class that handles a lot of string formatting, date displays, and similar functionality and it's a shared/static class. Is this the "correct" way of doing things or should we be instanciating the utility class as and when we need it? Our main goal here is to reduce memory footprint but performance of the application is also a consideration. Thanks, Matt PS. We're using .NET 2.0

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  • ASP.NET MVC Paging for a search form

    - by James Alexander
    I've read several different posts on paging w/ in MVC but none describe a scenario where I have something like a search form and then want to display the results of the search criteria (with paging) beneath the form once the user clicks submit. My problem is that, the paging solution I'm using will create <a href="..."> links that will pass the desired page like so: http://mysite.com/search/2/ and while that's all fine and dandy, I don't have the results of the query being sent to the db in memory or anything so I need to query the DB again. If the results are handled by the POST controller action for /Search and the first page of the data is rendered as such, how do I get the same results (based on the form criteria specified by the user) when the user clicks to move to page 2? Some javascript voodoo? Leverage Session State? Make my GET controller action have the same variables expected by the search criteria (but optional), when the GET action is called, instantiate a FormCollection instance, populate it and pass it to the POST action method (there-by satisfying DRY)? Can someone point me in the right direction for this scenario or provide examples that have been implemented in the past? Thanks!

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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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  • Is this a well known design pattern? what is it's name

    - by GenEric35
    Hi I have seen this often in code, but when I speak of it i don't know the name of such 'pattern' I have a method with 2 arguments that calls an overloaded method that has 3 arguments and intentionality sets the 3rd one to empty string. public DoWork(string name, string phoneNumber) { CreateContact(name, phoneNumber, string.Empty) } public DoWork(string name, string phoneNumber, string emailAddress) { //do the work } The reason I'm doing this is I to not duplicate code, and allow the existing callers to still call the method that has only 2 parameters. I have associate a few tags to this question, but it probably fit in more categories of questions. Is this a pattern, and does it have a name?

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