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• When to define SDD operations System->Actor?

  - by devoured elysium

  I am having some trouble understanding how to make SDDs, as I don't fully grasp why in some cases one should define operations for System - Actor and in others don't. Here is an example: 1) The User tells the System that wants to buy some tickets, stating his client number. 2) The System confirms that the given client number is valid. 3) The User tells the System the movie that wants to see. 4) The System shows the set of available sessions and seats for that movie. 5) The System asks the user which session/seat he wants. 6) The user tells the System the chosen session/seat. This would be converted to: a) -----> tellClientNumber(clientNumber) b) <----- validClientNumber c) -----> tellMovieToSee(movie) d) <----- showsAvailableSeatsHours e) -----> tellSystemChosenSessionSeat(session, seat) I know that when we are dealing with SDD's we are still far away from coding. But I can't help trying to imagine how it how it would have been had I to convert it right away to code: I can understand 1) and 2). It's like if it was a C#/Java method with the following signature: boolean tellClientNumber(clientNumber) so I put both on the SDD. Then, we have the pair 3) 4). I can imagine that as something as: SomeDataStructureThatHoldsAvailableSessionsSeats tellSystemMovieToSee(movie) Now, the problem: From what I've come to understand, my lecturer says that we shouldn't make an operation on the SDD for 5) as we should only show operations from the Actor to the System and when the System is either presenting us data (as in c)) or validating sent data (such as in b)). I find this odd, as if I try to imagine this like a DOS app where you have to put your input sequencially, it makes sense to make an arrow even for 5). Why is this wrong? How should I try to visualize this? Thanks

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• Define "Validation in the Model"

  - by sunwukung

  There have been a couple of discussions regarding the location of user input validation: http://stackoverflow.com/questions/659950/should-validation-be-done-in-form-objects-or-the-model http://stackoverflow.com/questions/134388/where-do-you-do-your-validation-model-controller-or-view These discussions were quite old, so I wanted to ask the question again to see if anyone had any fresh input. If not, I apologise in advance. If you come from the Validation in the Model camp - does Model mean OOP representation of data (i.e. Active Record/Data Mapper) as "Entity" (to borrow the DDD terminology) - in which case you would, I assume, want all Model classes to inherit common validation constraints. Or can these rules simply be part of a Service in the Model - i.e. a Validation service? For example, could you consider Zend_Form and it's validation classes part of the Model? The concept of a Domain Model does not appear to be limited to Entities, and so validation may not necessarily need to be confined to this Entities. It seems that you would require a lot of potentially superfluous handing of values and responses back and forth between forms and "Entities" - and in some instances you may not persist the data recieved from user input, or recieve it from user input at all.

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• Binded click loses context of my Class. JS

  - by Fabiano PS

  Hi, I have this problem that I probably understand but don't know how to handle, if there is a way. I have a class simplified as this: function DrawingTable(canvas_id){ this.canvas_id = canvas_id; bind_events() function bind_events(){ $(get_canvas()).click(function(e){ var canvas = get_canvas() //works do_something_in_the_instance_who_called_click() } function get_canvas(){return document.getElementById(canvas_id)} function do_something_in_the_instance_who_called_click(){ alert(this.canvas_id) //fail! } } Because when the click() is invoked for what it looks this is not inside the instance anymore, but I need to change atributes from there.. is there a way, given that may be multiple instances? I don't really know how but the get_canvas() works :) I'm using jQuery but likely not relevant

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• Database schema to store AND, OR relation, association

  - by user455387

  Many thanks for your help on this. In order for an entreprise to get a call for tender it must meet certain requirements. For the first example the enterprise must have a minimal class 4, and have qualification 2 in sector 5. Minimal class is always one number. Qualification can be anything (single, or multiple using AND, OR logical operators) I have created tables in order to map each number to it's given name. Now I need to store requirements in the database. minimal class 4 Sector Qualification 5.2 minimal class 2 Sector Qualifications 3.9 and 3.10 minimal class 3 Sector Qualifications 6.1 or 6.3 minimal class 1 Sector Qualifications (3.1 and 3.2) or 5.6 class Domain < ActiveRecord::Base has_many :domain_classes has_many :domain_sectors has_many :sector_qualifications, :through => :domain_sectors end class DomainClass < ActiveRecord::Base belongs_to :domain end class DomainSector < ActiveRecord::Base belongs_to :domain has_many :sector_qualifications end class SectorQualification < ActiveRecord::Base belongs_to :domain_sector end create_table "domains", :force => true do |t| t.string "name" end create_table "domain_classes", :force => true do |t| t.integer "number" t.integer "domain_id" end create_table "domain_sectors", :force => true do |t| t.string "name" t.integer "number" t.integer "domain_id" end create_table "sector_qualifications", :force => true do |t| t.string "name" t.integer "number" t.integer "domain_sector_id" end

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• MS Access: index optimisation

  - by Patrick Honorez

  Let's say we have a [Valuations] table containing several values per date and per fund: -FundId -ValDate -Value1 -Value2... The Primary key is obviously FundId+ValDate. I have also indexed the ValDate field since I often query for values on a specific date. My question is: should I also create a specific index for the FundId, or is MsAccess clever enough to use the Primary key when querying on a specific FundId ?

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• Storing information for drop-down menus

  - by Mark

  Suppose you're building an HTML form and you want to have 2 or more drop-down menus, where after picking an option from the first, the 2nd menu is populated, and so forth. For example, choosing a country would bring up a list of provinces for that country, which would in turn list the cities. How would you store that sort of information in a database? Would you have a table Countries(id, name), Provinces(id, country_id, name), Cities(id, province_id, name) or would you have just one big denormalized table Entries(country, province, city)? (Why?)

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• Elegent way to collapse or expand sub-sequences of a list in Python?

  - by forgot

  I want to collapse or expand sub-sequences of a list e.g. ['A', 'B', 'D', 'E', 'H'] -> ['AB', 'DE', 'H'] and vice versa currently I wrote some ugly code like: while True: for i, x in enumerate(s): if x == 'A' and s[i+1] == 'B': s[i:i+2] = 'AB' break else: break For people who asking 'why do that thing': Actually I'm working on a optimizing compiler and this is the peephole part. Writing pattern matching is a little annoying.

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• Sober, eye-catchy Color for Job site

  - by Knowledge Craving

  I will be creating one website related to jobs, which has almost all the features of monster & naukri. My client just asked to use any sober yet eye-catchy color(s) for that website. Can anybody please highlight as to what is / are the sober, yet eye-catchy color(s) for these type of websites?

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• Best way to track impressions/clicks in a bespoke advertisement system?

  - by Martin Bean

  I've been asked to create a bespoke advertisement system despite suggesting open source alternatives such as OpenX and DoubleClick for Publishers (the former Google Ad Manager). I've got the basics of the system set up, i.e. uploading creatives, creating positions and a mechanism to place creatives within positions; however, the area I'm stuck with is impression and click tracking. At the moment an impression and click is stored with the creative, but this then means impressions/clicks can't be queried. For example, we can't find how many impressions were in position x between date y and date z. How would I go about storing that kind of data? My theory was store the creative ID, position ID and timestamp in a database table, but given the amount of traffic the site has this would produce a very large database very quickly. If any one could give me a pointer or two, that would be great.

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• C++ Problem: Class Promotion using derived class

  - by Michael Fitzpatrick

  I have a class for Float32 that is derived from Float32_base class Float32_base { public: // Constructors Float32_base(float x) : value(x) {}; Float32_base(void) : value(0) {}; operator float32(void) {return value;}; Float32_base operator =(float x) {value = x; return *this;}; Float32_base operator +(float x) const { return value + x;}; protected: float value; } class Float32 : public Float32_base { public: float Tad() { return value + .01; } } int main() { Float32 x, y, z; x = 1; y = 2; // WILL NOT COMPILE! z = (x + y).Tad(); // COMPILES OK z = ((Float32)(x + y)).Tad(); } The issue is that the + operator returns a Float32_base and Tad() is not in that class. But 'x' and 'y' are Float32's. Is there a way that I can get the code in the first line to compile without having to resort to a typecast like I did on the next line?

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• HTML columns or rows for form layout?

  - by Valera

  I'm building a bunch of forms that have labels and corresponding fields (input element or more complex elements). Labels go on the left, fields go on the right. Labels in a given form should all be a specific width so that the fields all line up vertically. There are two ways (maybe more?) of achieving this: Rows: Float each label and each field left. Put each label and field in a field-row div/container. Set label width to some specific number. With this approach labels on different forms will have different widths, because they'll depend on the width of the text in the longest label. Columns: Put all labels in one div/container that's floated left, put all fields in another floated left container with padding-left set. This way the labels and even the label container don't need to have their widths set, because the column layout and the padding-left will uniformly take care of vertically lining up all the fields. So approach #2 seems to be easier to implement (because the widths don't need to be set all the time), but I think it's also less object oriented, because a label and a field that goes with that label are not grouped together, as they are in approach #1. Also, if building forms dynamically, approach #2 doesn't work as well with functions like addRow(label, field), since it would have to know about the label and the field containers, instead of just creating/adding one field-row element. Which approach do you think is better? Is there another, better approach than these two?

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• How can I handle all my errors/messages in one place on an Asp.Net page?

  - by Atomiton

  Hi all, I'm looking for some guidance here. On my site I put things in Web user controls. For example, I will have a NewsItem Control, an Article Control, a ContactForm control. These will appear in various places on my site. What I'm looking for is a way for these controls to pass messages up to the Page that they exist on. I don't want to tightly couple them, so I think I will have to do this with Events/Delegates. I'm a little unclear as to how I would implement this, though. A couple of examples: 1 A contact form is submitted. After it's submitted, instead of replacing itself with a "Your mail has been sent" which limits the placement of that message, I'd like to just notify the page that the control is on with a Status message and perhaps a suggested behaviour. So, a message would include the text to render as well as an enum like DisplayAs.Popup or DisplayAs.Success 2 An Article Control queries the database for an Article object. Database returns an Exception. Custom Exception is passed to the page along with the DisplayAs.Error enum. The page handles this error and displays it wherever the errors go. I'm trying to accomplish something similar to the ValidationSummary Control, except that I want the page to be able to display the messages as the enum feels fit. Again, I don't want to tightly bind or rely a control existing on the Page. I want the controls to raise these events, but the page can ignore them if it wants. Am I going about this the right way? I'd love a code sample just to get me started. I know this is a more involved question, so I'll wait longer before voting/choosing the answers.

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• Does this copy the reference or the object?

  - by Water Cooler v2

  Sorry, I am being both thick and lazy, but mostly lazy. Actually, not even that. I am trying to save time so I can do more in less time as there's a lot to be done. Does this copy the reference or the actual object data? public class Foo { private NameValueCollection _nvc = null; public Foo( NameValueCollection nvc) { _nvc = nvc; } } public class Bar { public static void Main() { NameValueCollection toPass = new NameValueCollection(); new Foo( toPass ); // I believe this only copies the reference // so if I ever wanted to compare toPass and // Foo._nvc (assuming I got hold of the private // field using reflection), I would only have to // compare the references and wouldn't have to compare // each string (deep copy compare), right? } I think I know the answer for sure: it only copies the reference. But I am not even sure why I am asking this. I guess my only concern is, if, after instantiating Foo by calling its parameterized ctor with toPass, if I needed to make sure that the NVC I passed as toPass and the NVC private field _nvc had the exact same content, I would just need to compare their references, right?

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• Arrow in nav menus in CSS/JS (e.g. playframework.org)

  - by manmal

  The navigation menu at the top of the www.playframework.org site features a small arrow pointing upward for the currently selected section (Home, Learn, Download,...). I tried to get behind the implementation they used, but I can't wrap my head around it - the resource does not show up in Chrome's Resources window, and an inspection of the elements did not show any signs of a background image, nor a JS interceptor (although I might have missed that). What in hellhound's name is going on there? :)

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• Stupid java question: Is it a method?

  - by Stefan

  Hello, I'm no Java guy, so I ask myself what this means: public Button(Light light) { this.light = light; } Is Button a method? I ask myself, because it takes an input parameter light. But if it was a method, why would it begin with a capital letter and has no return data type? Here comes the full example: public class Button { private Light light; public Button(Light light) { this.light = light; } public void press() { light.turnOn(); } } I know, this question is really trivial. However, I have nothing to do with Java and haven't found a description for the Button thing above. I'm just interested.

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• How do I link ASP.NET membership/role users to tables in db?

  - by SnapConfig.com

  I am going to use forms authentication but I want to be able to link the asp.net users to some tables in the db for example If I have a class and students (as roles) I'll have a class students table. I'm planning to put in a Users table containing a simple int userid and ASP.NET username in there and put userid wherever I want to link the users. Does that sound good? any other options of modeling this? it does sound a bit convoluted?

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• Is it correct to represent a foreign key on a conceptual data model?

  - by Zach

  Is it correct to represent a foreign key on a conceptual data model, or should I only introduce foreign keys when I am doing the relational model?

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• Possible to add an EventListener to a function for Actionscript 3?

  - by Tom

  I'm trying to setup something like Aspect Oriented Programming in Actionscript 3, basically the only thing I need to be able to do is something like this: SomeClass.getMethod("methodName").addEventListener(afterMethodExecuted, function() { //run code }); This way I can run code after (or before) any method in any class has run, allowing numerous new possibilities. How should I implement this?

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• Which entities should be Aggregate Roots?

  - by MylesRip

  If Book aggregates Chapter which in turn aggregates Page, then what should be the aggregate root? One possibility might be: Book is an aggregate root with Chapter as a leaf and Chapter is an aggregate with Page as a leaf. In this scenario, Chapter is a leaf in one aggregate and a root in another. Is this okay? Would it make sense in this scenario to have two repositories, one for Book and another for Chapter? If so, then couldn't the Chapter repository be used to circumvent the fact that access to Chapter should only happen via Book? What would be the best way to handle a situation like this?

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• When to define SDD(System Sequence Diagram) operations System->Actor?

  - by devoured elysium

  I am having some trouble understanding how to make System Sequence Diagrams, as I don't fully grasp why in some cases one should define operations for System - Actor and in others don't. Here is an example: Let's assume the System is a Cinema Ticket Store and the Actor is a client that wants to buy a ticket. 1) The User tells the System that wants to buy some tickets, stating his client number. 2) The System confirms that the given client number is valid. 3) The User tells the System the movie that wants to see. 4) The System shows the set of available sessions and seats for that movie. 5) The System asks the user which session/seat he wants. 6) The User tells the System the chosen session/seat. This would be converted to: a) -----> tellClientNumber(clientNumber) b) <----- validClientNumber c) -----> tellMovieToSee(movie) d) <----- showsAvailableSeatsHours e) -----> tellSystemChosenSessionSeat(session, seat) I know that when we are dealing with SDD's we are still far away from coding. But I can't help trying to imagine how it how it would have been had I to convert it right away to code: I can understand 1) and 2). It's like if it was a C#/Java method with the following signature: boolean tellClientNumber(clientNumber) so I put both on the SDD. Then, we have the pair 3) 4). I can imagine that as something as: SomeDataStructureThatHoldsAvailableSessionsSeats tellSystemMovieToSee(movie) Now, the problem: From what I've come to understand, my lecturer says that we shouldn't make an operation on the SDD for 5) as we should only show operations from the Actor to the System and when the System is either presenting us data (as in c)) or validating sent data (such as in b)). I find this odd, as if I try to imagine this like a DOS app where you have to put your input sequencially, it makes sense to make an arrow even for 5). Why is this wrong? How should I try to visualize this? Thanks

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• Would you store binary data in database or in file system?

  - by paul

  This is a question which has been asked before (large-text-and-images-in-sql) but mainly for data which will be changed. In my case the data will be stored and never changed. Just seems sensible to keep everything together. Are there any reasons why I should not store static binary data in a database? Assuming it is a sensible thing to do, are there any advantages to storing such data in separate tables? (You might begin to realise now that I'm not a DB expert...) Clarify: There will probably be no more than 10-20 users but these will be in the US and in the UK. The binary data will have to be transfered in any case.

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• Can I access elements/methods named "button1" "button2" "button3" etc. using "buttoni" inside a for-

  - by cksubs

  I have a bunch of buttons named: button1 button2 button3 etc. Is there a way to basically do this? pseudocode for(int i = 1, i < 15, i++) { button{i}.selected = YES; } This also goes for method calls, etc. I've often thought such a way of calling methods would be very convenient, but I don't think I've ever seen it done when using compiled languages. But I have done it using PHP. Is there any way to do this in Objective-C? (That's where my problem is now, but I'd also be interested in if you can do this in other languages.) Alternately, is there a reason why this is NOT a good way to go about accessing all the UI elements? Thanks!

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• How can a language be interpreted by itself (like Rubinius)?

  - by japancheese

  I've been programming in Ruby for a while now with just the standard MRI implementation of Ruby, but I've always been curious about the other implementations I hear so much about. I was reading about Rubinius the other day, a Ruby interpreter written in Ruby. I tried looking it up in various places, but I was having a hard time figuring out exactly how something like this works. I've never had much experience in compilers or language writing but I'm really interested to figure it out. How exactly can a language be interpreted by itself? Is there a basic step in compiling that I don't understand where this makes sense? Can someone explain this to me like I'm an idiot (because that wouldn't be too far off base anyways)

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• Would it be useful to change java to support both static and dynamic types?

  - by James A. N. Stauffer

  What if a Java allow both static and dynamic types. That might allow the best of both worlds. i.e.: String str = "Hello"; var temp = str; temp = 10; temp = temp * 5; Would that be possible? Would that be beneficial? Do any languages currently support both and how well does it work out? Here is a better example (generics can't be used but the program does know the type): var username = HttpServletRequest.getSession().getAttribute("username");//Returns a String if(username.length() == 0) { //Error }

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• How do you manage web navigation info in your application?

  - by Dave

  I’m building an application where different users will have different menu items available to them depending on what they’ve paid for. There will also be multiple levels to the menu hierarchy. What’s the best approach to this problem? I’m assuming I need a database table that represents the menu hierarchy, including the parent-child relationships of the nodes in the navigation as well as the sorting of the items. Then another table which I use to manage whether a user is authorized to access a particular item in that table. When I render the view, I’d reference the menus, and the access rights of the user to output the menu, and I’d also need a function to check that same authorization from each controller in case a user manually types in a URL of a controller they’re not supposed to have access to. Is this the right approach? Any suggestions for caching this to prevent the constant look-ups of this type of info? I’m open to any suggestions on how you may have approached this type of requirement.

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