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  • Transaction on Entity FrameWork Refactoring and best performance how can i?

    - by programmerist
    i try to use transaction in Entity FrameWork. i have 3 tables Personel, Prim, Finans. in Prim table you look SatisTutari (int) if i add data in SatisTutari.Text instead of int value adding float value. Trannsaction must be run! Everything is ok but how can i refactoring or give best performance or best writing Transaction coding! i have 3 table so i have 3 entities: CREATE TABLE Personel (PersonelID integer PRIMARY KEY identity not null, Ad varchar(30), Soyad varchar(30), Meslek varchar(100), DogumTarihi datetime, DogumYeri nvarchar(100), PirimToplami float); Go create TABLE Prim (PrimID integer PRIMARY KEY identity not null, PersonelID integer Foreign KEY references Personel(PersonelID), SatisTutari int, Prim float, SatisTarihi Datetime); Go CREATE TABLE Finans (ID integer PRIMARY KEY identity not null, Tutar float); Personel, Prim,Finans my tables. if you look Prim table you can see Prim value float value if i write a textbox not float value my transaction must run. protected void btnSave_Click(object sender, EventArgs e) { using (TestEntities testCtx = new TestEntities()) { using (TransactionScope scope = new TransactionScope()) { Personel personel = new Personel(); Prim prim = new Prim(); Finans finans = new Finans(); //-----------------------------------------------------------------------Step 1 personel.Ad = txtName.Text; personel.Soyad = txtSurName.Text; personel.Meslek = txtMeslek.Text; personel.DogumTarihi = DateTime.Parse(txtSatisTarihi.Text); personel.DogumYeri = txtDogumYeri.Text; personel.PirimToplami = float.Parse(txtPrimToplami.Text); testCtx.AddToPersonel(personel); testCtx.SaveChanges(); //----------------------------------------------------------------------- step 2 prim.PersonelID = personel.PersonelID; prim.SatisTutari = int.Parse(txtSatisTutari.Text); prim.SatisTarihi = DateTime.Parse(txtSatisTarihi.Text); prim.Prim1 = double.Parse(txtPrim.Text); finans.Tutar = prim.SatisTutari * prim.Prim1; testCtx.AddToPrim(prim); testCtx.SaveChanges(); //----------------------------------------------------------------------- step 3 lblTutar.Text = finans.Tutar.Value.ToString(); testCtx.AddToFinans(finans); testCtx.SaveChanges(); scope.Complete(); } } How can i rearrange codes. i need best practice refactoring and best solution for reading easly and performance!!!

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  • MVC validation error with strongly typed view

    - by Remnant
    I have a simple form that I would like to validate on form submission. Note I have stripped out the html for ease of viewing <%=Html.TextBox("LastName", "")%> //Lastname entry <%=Html.ValidationMessage("LastName")%> <%=Html.TextBox("FirstName", "")%>//Firstname entry <%=Html.ValidationMessage("FirstName")%> <%=Html.DropDownList("JobRole", Model.JobRoleList)%> //Dropdownlist of job roles <% foreach (var record in Model.Courses) // Checkboxes of different courses for user to select { %> <li><label><input type="checkbox" name="Courses" value="<%=record.CourseName%>" /><%= record.CourseName%></label></li> <% } %> On submission of this form I would like to check that both FirstName and LastName are populated (i.e. non-zero length). In my controller I have: public ActionResult Submit(string FirstName, string LastName) { if (FirstName.Trim().Length == 0) ModelState.AddModelError("FirstName", "You must enter a first name"); if (LastName.Trim().Length == 0) ModelState.AddModelError("LastName", "You must enter a first name"); if (ModelState.IsValid) { //Update database + redirect to action } return View(); //If ModelState not valid, return to View and show error messages } Unfortunately, this code logic produces an error that states that no objects are found for JobRole and Courses. If I remove the dropdownlist and checkboxes then all works fine. The issue appears to be that when I return the View the view is expecting objects for the dropwdownlist and checkboxes (which is sensible as that is what is in my View code) How can I overcome this problem? Things I have considered: In my controller I could create a JobRoleList object and Course object to pass to the View so that it has the objects to render. The issue with this is that it will overwrite any dropdownlist / checkbox selections that the user has already made. In the parameters of my controller method Submit I could aslo capture the JobRoleList object and Course object to pass back to the View. Again, not sure this would capture any items the user has already selected. I have done much googling and reading but I cannot find a good answer. When I look at examples in books or online (e.g. Nerddinner) all the validation examples involve simple forms with TextBox inputs and don't seems to show instances with multiple checkboxes and dropdownlists. Have I missed something obvious here? What would be best practice in this situation? Thanks

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  • Ninject with Object Initializers and LINQ

    - by Alexander Kahoun
    I'm new to Ninject so what I'm trying may not even be possible but I wanted to ask. I free-handed the below so there may be typos. Let's say I have an interface: public interface IPerson { string FirstName { get; set; } string LastName { get; set;} string GetFullName(); } And a concrete: public class Person : IPerson { public string FirstName { get; set; } public string LastName { get; set; } public string GetFullName() { return String.Concat(FirstName, " ", LastName); } } What I'm used to doing is something like this when I'm retrieving data from arrays or xml: public IEnumerable<IPerson> GetPeople(string xml) { XElement persons = XElement.Parse(xml); IEnumerable<IPerson> people = ( from person in persons.Descendants("person") select new Person { FirstName = person.Attribute("FName").Value, LastName = person.Attribute("LName").Value }).ToList(); return people; } I don't want to tightly couple the concrete to the interface in this manner. I haven't been able to find any information in regards to using Ninject with LINQ to Objects or with object initializers. I may be looking in the wrong places, but I've been searching for a day now with no luck at all. I was contemplating putting the kernel into an singleton instance and seeing if that would work, but I'm not sure that it will plus I've heard that passing your kernel around is a bad thing. I'm trying to implement this in a class library currently. If this is not possible, does anyone have any examples or suggestions as to what the best practice is in this case? Thanks in advance for the help. EDIT: Based on some of the answers I feel I should clarify. Yes, the example above appears short lived but it was simply an example of one piece that I was trying to do. Let's give a bigger picture. Say instead of XML I am gathering all my data through a 3rd party web service and I'm creating an interface for it, the data could be a defined object in the wsdl or it could sometimes be an xml string. IPerson could be used for both the Person object and a User object. I will be doing this inside of a separate class library, because it needs to be portable and will be used in other projects, and handing it to an MVC3 Web Application and the objects will be used in javascript as well. I appreciate all the input so far.

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  • c++ class member functions selected by traits

    - by Jive Dadson
    I am reluctant to say I can't figure this out, but I can't figure this out. I've googled and searched stackoverflow, and come up empty. The abstract, and possibly overly vague form of the question is, how can I use the traits-pattern to instantiate non-virtual member functions? The question came up while modernizing a set of multivariate function optimizers that I wrote more than 10 years ago. The optimizers all operate by selecting a straight-line path through the parameter space away from the current best point (the "update"), then finding a better point on that line (the "line search"), then testing for the "done" condition, and if not done, iterating. There are different methods for doing the update, the line-search, and conceivably for the done test, and other things. Mix and match. Different update formulae require different state-variable data. For example, the LMQN update requires a vector, and the BFGS update requires a matrix. If evaluating gradients is cheap, the line-search should do so. If not, it should use function evaluations only. Some methods require more accurate line-searches than others. Those are just some examples. The original version instatiates several of the combinations by means of virtual functions. Some traits are selected by setting mode bits. Yuck. It would be trivial to define the traits with #define's and the member functions with #ifdef's and macros. But that's so twenty years ago. It bugs me that I cannot figure out a whiz-bang modern way. If there were only one trait that varied, I could use the curiously recurring template pattern. But I see no way to extend that to arbitrary combinations of traits. I tried doing it using boost::enable_if, etc.. The specialized state info was easy. I managed to get the functions done, but only by resorting to non-friend external functions that have the this-pointer as a parameter. I never even figured out how to make the functions friends, much less member functions. Perhaps tag-dispatch is the key. I haven't gotten very deeply into that. Surely it's possible, right? If so, what is best practice?

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  • How and why do I set up a C# build machine?

    - by mmr
    Hi all, I'm working with a small (4 person) development team on a C# project. I've proposed setting up a build machine which will do nightly builds and tests of the project, because I understand that this is a Good Thing. Trouble is, we don't have a whole lot of budget here, so I have to justify the expense to the powers that be. So I want to know: What kind of tools/licenses will I need? Right now, we use Visual Studio and Smart Assembly to build, and Perforce for source control. Will I need something else, or is there an equivalent of a cron job for running automated scripts? What, exactly, will this get me, other than an indication of a broken build? Should I set up test projects in this solution (sln file) that will be run by these scripts, so I can have particular functions tested? We have, at the moment, two such tests, because we haven't had the time (or frankly, the experience) to make good unit tests. What kind of hardware will I need for this? Once a build has been finished and tested, is it a common practice to put that build up on an ftp site or have some other way for internal access? The idea is that this machine makes the build, and we all go to it, but can make debug builds if we have to. How often should we make this kind of build? How is space managed? If we make nightly builds, should we keep around all the old builds, or start to ditch them after about a week or so? Is there anything else I'm not seeing here? I realize that this is a very large topic, and I'm just starting out. I couldn't find a duplicate of this question here, and if there's a book out there I should just get, please let me know. EDIT: I finally got it to work! Hudson is completely fantastic, and FxCop is showing that some features we thought were implemented were actually incomplete. We also had to change the installer type from Old-And-Busted vdproj to New Hotness WiX. Basically, for those who are paying attention, if you can run your build from the command line, then you can put it into hudson. Making the build run from the command line via MSBuild is a useful exercise in itself, because it forces your tools to be current.

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  • Idiomatic use of auto_ptr to transfer ownership to a container

    - by heycam
    I'm refreshing my C++ knowledge after not having used it in anger for a number of years. In writing some code to implement some data structure for practice, I wanted to make sure that my code was exception safe. So I've tried to use std::auto_ptrs in what I think is an appropriate way. Simplifying somewhat, this is what I have: class Tree { public: ~Tree() { /* delete all Node*s in the tree */ } void insert(const string& to_insert); ... private: struct Node { ... vector<Node*> m_children; }; Node* m_root; }; template<T> void push_back(vector<T*>& v, auto_ptr<T> x) { v.push_back(x.get()); x.release(); } void Tree::insert(const string& to_insert) { Node* n = ...; // find where to insert the new node ... push_back(n->m_children, auto_ptr<Node>(new Node(to_insert)); ... } So I'm wrapping the function that would put the pointer into the container, vector::push_back, and relying on the by-value auto_ptr argument to ensure that the Node* is deleted if the vector resize fails. Is this an idiomatic use of auto_ptr to save a bit of boilerplate in my Tree::insert? Any improvements you can suggest? Otherwise I'd have to have something like: Node* n = ...; // find where to insert the new node auto_ptr<Node> new_node(new Node(to_insert)); n->m_children.push_back(new_node.get()); new_node.release(); which kind of clutters up what would have been a single line of code if I wasn't worrying about exception safety and a memory leak. (Actually I was wondering if I could post my whole code sample (about 300 lines) and ask people to critique it for idiomatic C++ usage in general, but I'm not sure whether that kind of question is appropriate on stackoverflow.)

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  • how to filter data from xml file for displaying only selected as nodes in treeview

    - by michale
    I have an xml file named "books.xml" provided in the link "http://msdn.microsoft.com/en-us/library/windows/desktop/ms762271(v=vs.85).aspx". What my requirement was to disaplay only the <title> from xml information as nodes in tree view. But when i did the following coding its displaying all the values as nodes like "catalog" as rootnode, book as parent node for all then author,title,genre etc as nodes but i want only root node catalogue and title as nodes not even book. Can any body guide me what modification i need to do in the exisitng logic for displaying title as nodes OpenFileDialog dlg = new OpenFileDialog(); dlg.Title = "Open XML document"; dlg.Filter = "XML Files (*.xml)|*.xml"; dlg.FileName = Application.StartupPath + "\\..\\..\\Sample.xml"; if (dlg.ShowDialog() == DialogResult.OK) { try { //Just a good practice -- change the cursor to a //wait cursor while the nodes populate this.Cursor = Cursors.WaitCursor; //First, we'll load the Xml document XmlDocument xDoc = new XmlDocument(); xDoc.Load(dlg.FileName); //Now, clear out the treeview, //and add the first (root) node treeView1.Nodes.Clear(); treeView1.Nodes.Add(new TreeNode(xDoc.DocumentElement.Name)); TreeNode tNode = new TreeNode(); tNode = (TreeNode)treeView1.Nodes[0]; //We make a call to addTreeNode, //where we'll add all of our nodes addTreeNode(xDoc.DocumentElement, tNode); //Expand the treeview to show all nodes treeView1.ExpandAll(); } catch (XmlException xExc) //Exception is thrown is there is an error in the Xml { MessageBox.Show(xExc.Message); } catch (Exception ex) //General exception { MessageBox.Show(ex.Message); } finally { this.Cursor = Cursors.Default; //Change the cursor back } }} //This function is called recursively until all nodes are loaded private void addTreeNode(XmlNode xmlNode, TreeNode treeNode) { XmlNode xNode; TreeNode tNode; XmlNodeList xNodeList; if (xmlNode.HasChildNodes) //The current node has children { xNodeList = xmlNode.ChildNodes; for (int x = 0; x <= xNodeList.Count - 1; x++) //Loop through the child nodes { xNode = xmlNode.ChildNodes[x]; treeNode.Nodes.Add(new TreeNode(xNode.Name)); tNode = treeNode.Nodes[x]; addTreeNode(xNode, tNode); } } else //No children, so add the outer xml (trimming off whitespace) treeNode.Text = xmlNode.OuterXml.Trim(); }

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  • Using MySQL to generate daily sales reports with filled gaps, grouped by currency

    - by Shane O'Grady
    I'm trying to create what I think is a relatively basic report for an online store, using MySQL 5.1.45 The store can receive payment in multiple currencies. I have created some sample tables with data and am trying to generate a straightforward tabular result set grouped by date and currency so that I can graph these figures. I want to see each currency that is available per date, with a 0 in the result if there were no sales in that currency for that day. If I can get that to work I want to do the same but also grouped by product id. In the sample data I have provided there are only 3 currencies and 2 product ids, but in practice there can be any number of each. I can correctly group by date, but then when I add a grouping by currency my query does not return what I want. I based my work off this article. My reporting query, grouped only by date: SELECT calendar.datefield AS date, IFNULL(SUM(orders.order_value),0) AS total_value FROM orders RIGHT JOIN calendar ON (DATE(orders.order_date) = calendar.datefield) WHERE (calendar.datefield BETWEEN (SELECT MIN(DATE(order_date)) FROM orders) AND (SELECT MAX(DATE(order_date)) FROM orders)) GROUP BY date Now grouped by date and currency: SELECT calendar.datefield AS date, orders.currency_id, IFNULL(SUM(orders.order_value),0) AS total_value FROM orders RIGHT JOIN calendar ON (DATE(orders.order_date) = calendar.datefield) WHERE (calendar.datefield BETWEEN (SELECT MIN(DATE(order_date)) FROM orders) AND (SELECT MAX(DATE(order_date)) FROM orders)) GROUP BY date, orders.currency_id The results I am getting (grouped by date and currency): +------------+-------------+-------------+ | date | currency_id | total_value | +------------+-------------+-------------+ | 2009-08-15 | 3 | 81.94 | | 2009-08-15 | 45 | 25.00 | | 2009-08-15 | 49 | 122.60 | | 2009-08-16 | NULL | 0.00 | | 2009-08-17 | 45 | 25.00 | | 2009-08-17 | 49 | 122.60 | | 2009-08-18 | 3 | 81.94 | | 2009-08-18 | 49 | 245.20 | +------------+-------------+-------------+ The results I want: +------------+-------------+-------------+ | date | currency_id | total_value | +------------+-------------+-------------+ | 2009-08-15 | 3 | 81.94 | | 2009-08-15 | 45 | 25.00 | | 2009-08-15 | 49 | 122.60 | | 2009-08-16 | 3 | 0.00 | | 2009-08-16 | 45 | 0.00 | | 2009-08-16 | 49 | 0.00 | | 2009-08-17 | 3 | 0.00 | | 2009-08-17 | 45 | 25.00 | | 2009-08-17 | 49 | 122.60 | | 2009-08-18 | 3 | 81.94 | | 2009-08-18 | 45 | 0.00 | | 2009-08-18 | 49 | 245.20 | +------------+-------------+-------------+ The schema and data I am using in my tests: CREATE TABLE orders ( id INT PRIMARY KEY AUTO_INCREMENT, order_date DATETIME, order_id INT, product_id INT, currency_id INT, order_value DECIMAL(9,2), customer_id INT ); INSERT INTO orders (order_date, order_id, product_id, currency_id, order_value, customer_id) VALUES ('2009-08-15 10:20:20', '123', '1', '45', '12.50', '322'), ('2009-08-15 12:30:20', '124', '1', '49', '122.60', '400'), ('2009-08-15 13:41:20', '125', '1', '3', '40.97', '324'), ('2009-08-15 10:20:20', '126', '2', '45', '12.50', '345'), ('2009-08-15 13:41:20', '131', '2', '3', '40.97', '756'), ('2009-08-17 10:20:20', '3234', '1', '45', '12.50', '1322'), ('2009-08-17 10:20:20', '4642', '2', '45', '12.50', '1345'), ('2009-08-17 12:30:20', '23', '2', '49', '122.60', '3142'), ('2009-08-18 12:30:20', '2131', '1', '49', '122.60', '4700'), ('2009-08-18 13:41:20', '4568', '1', '3', '40.97', '3274'), ('2009-08-18 12:30:20', '956', '2', '49', '122.60', '3542'), ('2009-08-18 13:41:20', '443', '2', '3', '40.97', '7556'); CREATE TABLE currency ( id INT PRIMARY KEY, name VARCHAR(255) ); INSERT INTO currency (id, name) VALUES (3, 'Euro'), (45, 'US Dollar'), (49, 'CA Dollar'); CREATE TABLE calendar (datefield DATE); DELIMITER | CREATE PROCEDURE fill_calendar(start_date DATE, end_date DATE) BEGIN DECLARE crt_date DATE; SET crt_date=start_date; WHILE crt_date < end_date DO INSERT INTO calendar VALUES(crt_date); SET crt_date = ADDDATE(crt_date, INTERVAL 1 DAY); END WHILE; END | DELIMITER ; CALL fill_calendar('2008-01-01', '2011-12-31');

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  • Best practices regarding equals: to overload or not to overload?

    - by polygenelubricants
    Consider the following snippet: import java.util.*; public class EqualsOverload { public static void main(String[] args) { class Thing { final int x; Thing(int x) { this.x = x; } public int hashCode() { return x; } public boolean equals(Thing other) { return this.x == other.x; } } List<Thing> myThings = Arrays.asList(new Thing(42)); System.out.println(myThings.contains(new Thing(42))); // prints "false" } } Note that contains returns false!!! We seems to have lost our things!! The bug, of course, is the fact that we've accidentally overloaded, instead of overridden, Object.equals(Object). If we had written class Thing as follows instead, then contains returns true as expected. class Thing { final int x; Thing(int x) { this.x = x; } public int hashCode() { return x; } @Override public boolean equals(Object o) { return (o instanceof Thing) && (this.x == ((Thing) o).x); } } Effective Java 2nd Edition, Item 36: Consistently use the Override annotation, uses essentially the same argument to recommend that @Override should be used consistently. This advice is good, of course, for if we had tried to declare @Override equals(Thing other) in the first snippet, our friendly little compiler would immediately point out our silly little mistake, since it's an overload, not an override. What the book doesn't specifically cover, however, is whether overloading equals is a good idea to begin with. Essentially, there are 3 situations: Overload only, no override -- ALMOST CERTAINLY WRONG! This is essentially the first snippet above Override only (no overload) -- one way to fix This is essentially the second snippet above Overload and override combo -- another way to fix The 3rd situation is illustrated by the following snippet: class Thing { final int x; Thing(int x) { this.x = x; } public int hashCode() { return x; } public boolean equals(Thing other) { return this.x == other.x; } @Override public boolean equals(Object o) { return (o instanceof Thing) && (this.equals((Thing) o)); } } Here, even though we now have 2 equals method, there is still one equality logic, and it's located in the overload. The @Override simply delegates to the overload. So the questions are: What are the pros and cons of "override only" vs "overload & override combo"? Is there a justification for overloading equals, or is this almost certainly a bad practice?

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  • Recommendations for a C++ polymorphic, seekable, binary I/O interface

    - by Trevor Robinson
    I've been using std::istream and ostream as a polymorphic interface for random-access binary I/O in C++, but it seems suboptimal in numerous ways: 64-bit seeks are non-portable and error-prone due to streampos/streamoff limitations; currently using boost/iostreams/positioning.hpp as a workaround, but it requires vigilance Missing operations such as truncating or extending a file (ala POSIX ftruncate) Inconsistency between concrete implementations; e.g. stringstream has independent get/put positions whereas filestream does not Inconsistency between platform implementations; e.g. behavior of seeking pass the end of a file or usage of failbit/badbit on errors Don't need all the formatting facilities of stream or possibly even the buffering of streambuf streambuf error reporting (i.e. exceptions vs. returning an error indicator) is supposedly implementation-dependent in practice I like the simplified interface provided by the Boost.Iostreams Device concept, but it's provided as function templates rather than a polymorphic class. (There is a device class, but it's not polymorphic and is just an implementation helper class not necessarily used by the supplied device implementations.) I'm primarily using large disk files, but I really want polymorphism so I can easily substitute alternate implementations (e.g. use stringstream instead of fstream for unit tests) without all the complexity and compile-time coupling of deep template instantiation. Does anyone have any recommendations of a standard approach to this? It seems like a common situation, so I don't want to invent my own interfaces unnecessarily. As an example, something like java.nio.FileChannel seems ideal. My best solution so far is to put a thin polymorphic layer on top of Boost.Iostreams devices. For example: class my_istream { public: virtual std::streampos seek(stream_offset off, std::ios_base::seekdir way) = 0; virtual std::streamsize read(char* s, std::streamsize n) = 0; virtual void close() = 0; }; template <class T> class boost_istream : public my_istream { public: boost_istream(const T& device) : m_device(device) { } virtual std::streampos seek(stream_offset off, std::ios_base::seekdir way) { return boost::iostreams::seek(m_device, off, way); } virtual std::streamsize read(char* s, std::streamsize n) { return boost::iostreams::read(m_device, s, n); } virtual void close() { boost::iostreams::close(m_device); } private: T m_device; };

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  • How to get started with testing(jMock)

    - by London
    Hello, I'm trying to learn how to write tests. I'm also learning Java, I was told I should learn/use/practice jMock, I've found some articles online that help to certain extend like : http://www.theserverside.com/news/1365050/Using-JMock-in-Test-Driven-Development http://jeantessier.com/SoftwareEngineering/Mocking.html#jMock And most articles I found was about test driven development, write tests first then write code to make the test pass. I'm not looking for that at the moment, I'm trying to write tests for already existing code with jMock. The official documentation is vague to say the least and just too hard for me. Does anybody have better way to learn this. Good books/links/tutorials would help me a lot. thank you EDIT - more concrete question : http://jeantessier.com/SoftwareEngineering/Mocking.html#jMock - from this article Tried this to mock this simple class : import java.util.Map; public class Cache { private Map<Integer, String> underlyingStorage; public Cache(Map<Integer, String> underlyingStorage) { this.underlyingStorage = underlyingStorage; } public String get(int key) { return underlyingStorage.get(key); } public void add(int key, String value) { underlyingStorage.put(key, value); } public void remove(int key) { underlyingStorage.remove(key); } public int size() { return underlyingStorage.size(); } public void clear() { underlyingStorage.clear(); } } Here is how I tried to create a test/mock : public class CacheTest extends TestCase { private Mockery context; private Map mockMap; private Cache cache; @Override @Before public void setUp() { context = new Mockery() { { setImposteriser(ClassImposteriser.INSTANCE); } }; mockMap = context.mock(Map.class); cache = new Cache(mockMap); } public void testCache() { context.checking(new Expectations() {{ atLeast(1).of(mockMap).size(); will(returnValue(int.class)); }}); } } It passes the test and basically does nothing, what I wanted is to create a map and check its size, and you know work some variations try to get a grip on this. Understand better trough examples, what else could I test here or any other exercises would help me a lot. tnx

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  • Implementing a logging library in .NET with a database as the storage medium

    - by Dave
    I'm just starting to work on a logging library that everyone can use to keep track of any sort of system information while the user is running our application. The simplest example so far is to track Info, Warnings, and Errors. I want all plugins to be able to use this feature, but since each developer might have a different idea of what's important to report, I want to keep this as generic as possible. In the C++ world, I would normally use something like a stl::pair<string,string> to act as a key value pair structure, and have a stl::list of these to act as a "row" in the log. The log cache would then be a list<list<pair<string,string>>> (ugh!). This way, the developers can use a const string key like INFO, WARNING, ERROR to have a consistent naming for a column in the database (for SELECTing specific types of information). I'd like the database to be able to deal with any number of distinct column names. For example, John might have an INFO row with a column called USER, and Bill might have an INFO row with a column called FILENAME. I want the log viewer to be able to display all information, and if one report doesn't have a value for INFO / FILENAME, those fields should just appear blank. So one option is to use List<List<KeyValuePair<String,String>>, and the another is to have the log library consumer somehow "register" its schema, and then have the database do an ALTER TABLE to handle this situation. Yet another idea is to have a table that's just for key value pairs, with a foreign key that maps the key value pairs back to the original log entry. I obviously don't want logging to bog down the system, so I only lock the log cache to make a copy of the data (and remove the already-copied data), then a background thread will dump the information to the database. My specific questions regarding this are: Do you see any performance issues? In other words, have you ever tried something like this and found that certain things just don't work well in practice? Is there a more .NETish way to implement the key value pairs, other than List<List<KeyValuePair<String,String>>>? Even if there is a way to do #2 better, is the ALTER TABLE idea I proposed above a Bad Thing? Would you recommend multiple databases over a single one? I don't yet have an idea of how frequently the log would get written to, but we ideally would like to have lots of low level information. Perhaps there should be a DB with a fixed schema only for the low level stuff, and then another DB that's more flexible for reporting information back to users.

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  • Objective-c design advice for use of different data sources, swapping between test and live

    - by user200341
    I'm in the process of designing an application that is part of a larger piece of work, depending on other people to build an API that the app can make use of to retrieve data. While I was thinking about how to setup this project and design the architecture around it, something occurred to me, and I'm sure many people have been in similar situations. Since my work is depending on other people to complete their tasks, and a test server, this slows work down at my end. So the question is: What's the best practice for creating test repositories and classes, implementing them, and not having to depend on altering several places in the code to swap between the test classes and the actual repositories / proper api calls. Contemplate the following scenario: GetDataFromApiCommand *getDataCommand = [[GetDataFromApiCommand alloc]init]; getDataCommand.delegate = self; [getDataCommand getData]; Once the data is available via the API, "GetDataFromApiCommand" could use the actual API, but until then a set of mock data could be returned upon the call of [getDataCommand getData] There might be multiple instances of this, in various places in the code, so replacing all of them wherever they are, is a slow and painful process which inevitably leads to one or two being overlooked. In strongly typed languages we could use dependency injection and just alter one place. In objective-c a factory pattern could be implemented, but is that the best route to go for this? GetDataFromApiCommand *getDataCommand = [GetDataFromApiCommandFactory buildGetDataFromApiCommand]; getDataCommand.delegate = self; [getDataCommand getData]; What is the best practices to achieve this result? Since this would be most useful, even if you have the actual API available, to run tests, or work off-line, the ApiCommands would not necessarily have to be replaced permanently, but the option to select "Do I want to use TestApiCommand or ApiCommand". It is more interesting to have the option to switch between: All commands are test and All command use the live API, rather than selecting them one by one, however that would also be useful to do for testing one or two actual API commands, mixing them with test data. EDIT The way I have chosen to go with this is to use the factory pattern. I set up the factory as follows: @implementation ApiCommandFactory + (ApiCommand *)newApiCommand { // return [[ApiCommand alloc]init]; return [[ApiCommandMock alloc]init]; } @end And anywhere I want to use the ApiCommand class: GetDataFromApiCommand *getDataCommand = [ApiCommandFactory newApiCommand]; When the actual API call is required, the comments can be removed and the mock can be commented out. Using new in the message name implies that who ever uses the factory to get an object, is responsible for releasing it (since we want to avoid autorelease on the iPhone). If additional parameters are required, the factory needs to take these into consideration i.e: [ApiCommandFactory newSecondApiCommand:@"param1"]; This will work quite well with repositories as well.

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  • Should I add try/catch around when casting on an attribute of JSP implicit object?

    - by Michael Mao
    Hi all: Basically what I mean is like this: List<String[]> routes = (List<String[]>)application.getAttribute("routes"); For the above code, it tries to get an attribute named "routes" from the JSP implicit object - application. But as everyone knows, after this line of code, routes may very well contains a null - which means this application hasn't got an attribute named "routes". Is this "casting on null" good programming practice in Java or not? Basically I try to avoid exceptions such as java.io.InvalidCastException I reckon things like this are more as "heritage" of Java 1.4 when generic types were not introduced to this language. So I guess everything stored in application attributes as Objects (Similar to traditional ArrayList). And when you do "downcast", there might be invalid casts. What would you do in this case? Update: Just found that although in the implicit object application I did store a List of String arrays, when I do this : List<double[]> routes = (List<double[]>)application.getAttribute("routes"); It doesn't produce any error... And I felt not comfortable already... And even with this code: out.print(routes.get(0)); It does print out something strange : [Ljava.lang.String;@18b352f Am I printing a "pointer to String"? I can finally get an exception like this: out.print(routes.get(0)[1]); with error : java.lang.ClassCastException: [Ljava.lang.String; Because it was me to add the application attribute, I know which type should it be cast to. I feel this is not "good enough", what if I forget the exact type? I know there are still some cases where this sort of thing would happen, such as in JSP/Servlet when you do casting on session attributes. Is there a better way to do this? Before you say:"OMG, why you don't use Servlets???", I should justify my reason as this: - because my uni sucks, its server can only work with Servlets generated by JSP, and I don't really want to learn how to fix issues like that. look at my previous question on this , and this is uni homework, so I've got no other choice, forget all about war, WEB-INF,etc, but "code everything directly into JSP" - because the professors do that too. :)

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  • What would you suggest as a high school first language?

    - by ldigas
    Edit by OA: After reading some answers I'll just update the question a little. At first I put it a little bluntly, but some of those gave me some good arguments which have to be taken into consideration while making a stand on this one. (these are mostly picked up from comments and answers below). A few things to take into account: to many pupils this is a first programming language - at this stage most of them have trouble grasping a difference between data types, variable passing, ... and whatnot, less alone pointers and similar 'low level stuff' :) they will all have to pass this to get into next grade (well, big majority of them anyway) not all of them have computers at home, not all of them are willing to learn this, less alone interested in - so the concepts have to be taught on a finite time scale in school hours (as well as practice on computers) free literature is a bonus - the teacher will make some scripts and handaways, but still ... I wouldn't like to bear the parents with the burden of buying expensive literature (also, english is not a native language here ... and although they are all learning it, their ability to read it fluently is somewhat questionable) somebody gave an argument - "a language which does not get in the way of ideas" - good one accessibility on different platforms in not expecially important at this point - although most of the suggested ones are available on win as well as linux - not many macs in this part of europe (their prices are sky high for anything but specialised usage) I will check what are the licencing issues on ms express editions about using it massively in high schools for purposes like this - if someone has any info about this, please, do not be shy with it :) A friend of mine, informatics teacher - in EU it comes as something as junior cs teacher, in a local high school asked me what I thought about what should be the first language pupils should be taught? It is a technical school (a little more oriented towards mathematics than the gymnasium, but not computer oriented totally). So I'm asking you - what do you think should be the first language pupils are exposed to in highschool? They have been teaching Pascal so far, but she's not sure that's a good course. She thought about switching to C (which I resented; considering not all pupils have interests in programming, to start with, and should be taught something higher level since they are just gripping the idea of a loop and such ... for a start), I suggested python or ruby (preferably py since it handles all paradigms). What is your opinion on this one? I looked, but didn't find a similar question on SO, so if there is one, please just point me towards it. Edit: The assumption is that none of the pupils have been exposed to any programming in junior school. See also: What is the best way to teach young kids some basic programming concepts? Best ways to teach a beginner to program How and when do you teach a kid to code What is the easiest language to start with? High School Programming

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  • Calculating rotation and translation matrices between two odometry positions for monocular linear triangulation

    - by user1298891
    Recently I've been trying to implement a system to identify and triangulate the 3D position of an object in a robotic system. The general outline of the process goes as follows: Identify the object using SURF matching, from a set of "training" images to the actual live feed from the camera Move/rotate the robot a certain amount Identify the object using SURF again in this new view Now I have: a set of corresponding 2D points (same object from the two different views), two odometry locations (position + orientation), and camera intrinsics (focal length, principal point, etc.) since it's been calibrated beforehand, so I should be able to create the 2 projection matrices and triangulate using a basic linear triangulation method as in Hartley & Zissermann's book Multiple View Geometry, pg. 312. Solve the AX = 0 equation for each of the corresponding 2D points, then take the average In practice, the triangulation only works when there's almost no change in rotation; if the robot even rotates a slight bit while moving (due to e.g. wheel slippage) then the estimate is way off. This also applies for simulation. Since I can only post two hyperlinks, here's a link to a page with images from the simulation (on the map, the red square is simulated robot position and orientation, and the yellow square is estimated position of the object using linear triangulation.) So you can see that the estimate is thrown way off even by a little rotation, as in Position 2 on that page (that was 15 degrees; if I rotate it any more then the estimate is completely off the map), even in a simulated environment where a perfect calibration matrix is known. In a real environment when I actually move around with the robot, it's worse. There aren't any problems with obtaining point correspondences, nor with actually solving the AX = 0 equation once I compute the A matrix, so I figure it probably has to do with how I'm setting up the two camera projection matrices, specifically how I'm calculating the translation and rotation matrices from the position/orientation info I have relative to the world frame. How I'm doing that right now is: Rotation matrix is composed by creating a 1x3 matrix [0, (change in orientation angle), 0] and then converting that to a 3x3 one using OpenCV's Rodrigues function Translation matrix is composed by rotating the two points (start angle) degrees and then subtracting the final position from the initial position, in order to get the robot's straight and lateral movement relative to its starting orientation Which results in the first projection matrix being K [I | 0] and the second being K [R | T], with R and T calculated as described above. Is there anything I'm doing really wrong here? Or could it possibly be some other problem? Any help would be greatly appreciated.

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  • Is it ok to dynamic cast "this" as a return value?

    - by Panayiotis Karabassis
    This is more of a design question. I have a template class, and I want to add extra methods to it depending on the template type. To practice the DRY principle, I have come up with this pattern (definitions intentionally omitted): template <class T> class BaseVector: public boost::array<T, 3> { protected: BaseVector<T>(const T x, const T y, const T z); public: bool operator == (const Vector<T> &other) const; Vector<T> operator + (const Vector<T> &other) const; Vector<T> operator - (const Vector<T> &other) const; Vector<T> &operator += (const Vector<T> &other) { (*this)[0] += other[0]; (*this)[1] += other[1]; (*this)[2] += other[2]; return *dynamic_cast<Vector<T> * const>(this); } } template <class T> class Vector : public BaseVector<T> { public: Vector<T>(const T x, const T y, const T z) : BaseVector<T>(x, y, z) { } }; template <> class Vector<double> : public BaseVector<double> { public: Vector<double>(const double x, const double y, const double z); Vector<double>(const Vector<int> &other); double norm() const; }; I intend BaseVector to be nothing more than an implementation detail. This works, but I am concerned about operator+=. My question is: is the dynamic cast of the this pointer a code smell? Is there a better way to achieve what I am trying to do (avoid code duplication, and unnecessary casts in the user code)? Or am I safe since, the BaseVector constructor is private?

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  • Is this a legitimate implementation of a 'remember me' function for my web app?

    - by user246114
    Hi, I'm trying to add a "remember me" feature to my web app to let a user stay logged in between browser restarts. I think I got the bulk of it. I'm using google app engine for the backend which lets me use java servlets. Here is some pseudo-code to demo: public class MyServlet { public void handleRequest() { if (getThreadLocalRequest().getSession().getAttribute("user") != null) { // User already has session running for them. } else { // No session, but check if they chose 'remember me' during // their initial login, if so we can have them 'auto log in' // now. Cookie[] cookies = getThreadLocalRequest().getCookies(); if (cookies.find("rememberMePlz").exists()) { // The value of this cookie is the cookie id, which is a // unique string that is in no way based upon the user's // name/email/id, and is hard to randomly generate. String cookieid = cookies.find("rememberMePlz").value(); // Get the user object associated with this cookie id from // the data store, would probably be a two-step process like: // // select * from cookies where cookieid = 'cookieid'; // select * from users where userid = 'userid fetched from above select'; User user = DataStore.getUserByCookieId(cookieid); if (user != null) { // Start session for them. getThreadLocalRequest().getSession() .setAttribute("user", user); } else { // Either couldn't find a matching cookie with the // supplied id, or maybe we expired the cookie on // our side or blocked it. } } } } } // On first login, if user wanted us to remember them, we'd generate // an instance of this object for them in the data store. We send the // cookieid value down to the client and they persist it on their side // in the "rememberMePlz" cookie. public class CookieLong { private String mCookieId; private String mUserId; private long mExpirationDate; } Alright, this all makes sense. The only frightening thing is what happens if someone finds out the value of the cookie? A malicious individual could set that cookie in their browser and access my site, and essentially be logged in as the user associated with it! On the same note, I guess this is why the cookie ids must be difficult to randomly generate, because a malicious user doesn't have to steal someone's cookie - they could just randomly assign cookie values and start logging in as whichever user happens to be associated with that cookie, if any, right? Scary stuff, I feel like I should at least include the username in the client cookie such that when it presents itself to the server, I won't auto-login unless the username+cookieid match in the DataStore. Any comments would be great, I'm new to this and trying to figure out a best practice. I'm not writing a site which contains any sensitive personal information, but I'd like to minimize any potential for abuse all the same, Thanks

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  • Slow MySQL query....only sometimes

    - by Shane N
    I have a query that's used in a reporting system of ours that sometimes runs quicker than a second, and other times takes 1 to 10 minutes to run. Here's the entry from the slow query log: # Query_time: 543 Lock_time: 0 Rows_sent: 0 Rows_examined: 124948974 use statsdb; SELECT count(distinct Visits.visitorid) as 'uniques' FROM Visits,Visitors WHERE Visits.visitorid=Visitors.visitorid and candidateid in (32) and visittime>=1275721200 and visittime<=1275807599 and (omit=0 or omit>=1275807599) AND Visitors.segmentid=9 AND Visits.visitorid NOT IN (SELECT Visits.visitorid FROM Visits,Visitors WHERE Visits.visitorid=Visitors.visitorid and candidateid in (32) and visittime<1275721200 and (omit=0 or omit>=1275807599) AND Visitors.segmentid=9); It's basically counting unique visitors, and it's doing that by counting the visitors for today and then substracting those that have been here before. If you know of a better way to do this, let me know. I just don't understand why sometimes it can be so quick, and other times takes so long - even with the same exact query under the same server load. Here's the EXPLAIN on this query. As you can see it's using the indexes I've set up: id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY Visits range visittime_visitorid,visitorid visittime_visitorid 4 NULL 82500 Using where; Using index 1 PRIMARY Visitors eq_ref PRIMARY,cand_visitor_omit PRIMARY 8 statsdb.Visits.visitorid 1 Using where 2 DEPENDENT SUBQUERY Visits ref visittime_visitorid,visitorid visitorid 8 func 1 Using where 2 DEPENDENT SUBQUERY Visitors eq_ref PRIMARY,cand_visitor_omit PRIMARY 8 statsdb.Visits.visitorid 1 Using where I tried to optimize the query a few weeks ago and came up with a variation that consistently took about 2 seconds, but in practice it ended up taking more time since 90% of the time the old query returned much quicker. Two seconds per query is too long because we are calling the query up to 50 times per page load, with different time periods. Could the quick behavior be due to the query being saved in the query cache? I tried running 'RESET QUERY CACHE' and 'FLUSH TABLES' between my benchmark tests and I was still getting quick results most of the time. Note: last night while running the query I got an error: Unable to save result set. My initial research shows that may be due to a corrupt table that needs repair. Could this be the reason for the behavior I'm seeing? In case you want server info: Accessing via PHP 4.4.4 MySQL 4.1.22 All tables are InnoDB We run optimize table on all tables weekly The sum of both the tables used in the query is 500 MB MySQL config: key_buffer = 350M max_allowed_packet = 16M thread_stack = 128K sort_buffer = 14M read_buffer = 1M bulk_insert_buffer_size = 400M set-variable = max_connections=150 query_cache_limit = 1048576 query_cache_size = 50777216 query_cache_type = 1 tmp_table_size = 203554432 table_cache = 120 thread_cache_size = 4 wait_timeout = 28800 skip-external-locking innodb_file_per_table innodb_buffer_pool_size = 3512M innodb_log_file_size=100M innodb_log_buffer_size=4M

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  • Live search results as you type... am I going about this the right way? jQuery + PHP

    - by dallen
    This is my first time building a tool like this, so please bare with me. I'm doing this to learn more about jQuery and AJAX. Basically, I have a search input and a hidden div. When you start typing in the search input, the hidden div becomes visible and results are brought in. In this case, I'm searching for client names. It all works fine, however I think my code could be better but I'm not sure exactly where to begin. Each keyup requests a PHP script which accesses a table in a database to find a like string. But in my PHP script, I'm echo'ing some JS/jQuery which I'm not sure is good practice. Below is my code. Am I going about this the right way or am I totally off base? Any suggestions for improvement? Javascript $("#search").keyup(function() { $("#search_results").show("fast"); $.ajax ({ type: "POST", url: "http://localhost:8888/index.php/welcome/search/" + $("#search").val(), success: function(html) { $("#search_results").html(html); } }); }); PHP function search($search_string = false) { if ($search_string) { $this->db->like('name', $search_string); $query = $this->db->get('clients'); if ($query->num_rows() == 0) { echo "No client exists."; } else { foreach ($query->result() as $row) { echo '<script>'; echo ' $("#client_results_'.$row->id.'").hide(); $("#'.$row->id.'").toggle(function() { $.ajax ({ type: "POST", url: "http://localhost:8888/index.php/welcome/search_client_ads/" + '.$row->id.', success: function(html) { $("#client_results_'.$row->id.'").html(html).show("fast"); } }); }, function() { $("#client_results_'.$row->id.'").hide("fast").html(""); });'; echo '</script>'; echo '<p><span id="'.$row->id.'">'.$row->name.'</span></p>'; echo '<div id="client_results_'.$row->id.'"></div>'; } } } else { echo ''; } } function search_client_ads($client_id) { $query = $this->db->get_where('online_ads', array('client' => $client_id)); if ($query->num_rows() == 0) { echo "No ads exist."; } else { foreach ($query->result() as $row) { echo $row->id; } } }

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  • .Net Remote Log Querying

    - by jlafay
    I have a Win Service that I'm working on that consists of the service, WF Service (using WorkflowServiceHost), a Workflow (WorkflowApplication) that queries/processes data from a SQL Server DB, and a Comm Marshall class that handles data flow between the service and the WF. The WF does a lot of heavy data processing and the original app (early VB6) logged all the processing and displayed the results on the screen of the host machine. Critical events will be committed to eventlog because I strongly believe that should be common practice because admins naturally will look there and because it already has support for remote viewing. The workflow will also need to write logging events as it processes and iterates according to our business logic. Such as: records queried, records returned, processed records, etc. The data is very critical and we need to log actions as they occur. The logs are currently kept as text files on disk and I think that is ok. Ideally I would like to record log events in XML so it's easier to query and because it is less costly than a DB, especially since our DB servers do a lot of heavy processing anyways. Since we are replacing essentially a VB6 application with a robust windows service (taking advantage of WF 4.0), it has been requested that a remote client also be created. It receives callbacks from the service after subscribing to it and being added to a collection of subscribers. Basic statistics and summaries are updated client side after receiving basic monitoring data of what is going on with the service. We would like to also provide a way to provide details when we need to examine what is going on further because this is a long running data processing service and issues need to be addressed immediately. What is the best way to implement some type of query from the client that is sent to the service and returned to the client? Would it be efficient to implement another method to expose on the service and then have that pass that off to some querying class/object to examine the XML files by whichever specification and then return it to the client? That's the main concern. I don't want the service to processing to bottleneck much while this occurs. It seems that WF already auto-magically threads well for the most part but I want to make sure this is the right way to go about it. Any suggestions/recommendations on how to architect and implement a small log querying framework for a remote service would be awesome.

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  • c++ class member functions instatiated by traits

    - by Jive Dadson
    I am reluctant to say I can't figure this out, but I can't figure this out. I've googled and searched stackoverflow, and come up empty. The abstract, and possibly overly vague form of the question is, how can I use the traits-pattern to instantiate non-virtual member functions? The question came up while modernizing a set of multivariate function optimizers that I wrote more than 10 years ago. The optimizers all operate by selecting a straight-line path through the parameter space away from the current best point (the "update"), then finding a better point on that line (the "line search"), then testing for the "done" condition, and if not done, iterating. There are different methods for doing the update, the line-search, and conceivably for the done test, and other things. Mix and match. Different update formulae require different state-variable data. For example, the LMQN update requires a vector, and the BFGS update requires a matrix. If evaluating gradients is cheap, the line-search should do so. If not, it should use function evaluations only. Some methods require more accurate line-searches than others. Those are just some examples. The original version instantiates several of the combinations by means of virtual functions. Some traits are selected by setting mode bits that are tested at runtime. Yuck. It would be trivial to define the traits with #define's and the member functions with #ifdef's and macros. But that's so twenty years ago. It bugs me that I cannot figure out a whiz-bang modern way. If there were only one trait that varied, I could use the curiously recurring template pattern. But I see no way to extend that to arbitrary combinations of traits. I tried doing it using boost::enable_if, etc.. The specialized state info was easy. I managed to get the functions done, but only by resorting to non-friend external functions that have the this-pointer as a parameter. I never even figured out how to make the functions friends, much less member functions. The compiler (vc++ 2008) always complained that things didn't match. I would yell, "SFINAE, you moron!" but the moron is probably me. Perhaps tag-dispatch is the key. I haven't gotten very deeply into that. Surely it's possible, right? If so, what is best practice?

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  • Which style is preferable when writing this boolean expression?

    - by Jeppe Stig Nielsen
    I know this question is to some degree a matter of taste. I admit this is not something I don't understand, it's just something I want to hear others' opinion about. I need to write a method that takes two arguments, a boolean and a string. The boolean is in a sense (which will be obvious shortly) redundant, but it is part of a specification that the method must take in both arguments, and must raise an exception with a specific message text if the boolean has the "wrong" value. The bool must be true if and only if the string is not null or empty. So here are some different styles to write (hopefully!) the same thing. Which one do you find is the most readable, and compliant with good coding practice? // option A: Use two if, repeat throw statement and duplication of message string public void SomeMethod(bool useName, string name) { if (useName && string.IsNullOrEmpty(name)) throw new SomeException("..."); if (!useName && !string.IsNullOrEmpty(name)) throw new SomeException("..."); // rest of method } // option B: Long expression but using only && and || public void SomeMethod(bool useName, string name) { if (useName && string.IsNullOrEmpty(name) || !useName && !string.IsNullOrEmpty(name)) throw new SomeException("..."); // rest of method } // option C: With == operator between booleans public void SomeMethod(bool useName, string name) { if (useName == string.IsNullOrEmpty(name)) throw new SomeException("..."); // rest of method } // option D1: With XOR operator public void SomeMethod(bool useName, string name) { if (!(useName ^ string.IsNullOrEmpty(name))) throw new SomeException("..."); // rest of method } // option D2: With XOR operator public void SomeMethod(bool useName, string name) { if (useName ^ !string.IsNullOrEmpty(name)) throw new SomeException("..."); // rest of method } Of course you're welcome to suggest other possibilities too. Message text "..." would be something like "If 'useName' is true a name must be given, and if 'useName' is false no name is allowed".

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  • 2nd Year College - Learning - Microsoft Server Products

    - by Ryan
    As the title says, I just finished my first year of college (majoring in Software Engineering). Fortunately my school likes Microsoft enough, and I can get pretty much anything I want that Microsoft sells. I also can get IBM Websphere and the like for free as well. Earlier this year, I set up an oldish computer (2.6 Pentium D, x64) to run ubuntu server headless. I'm predominately a Java developer, so Apache, Maven, Nexus, Sonar, SVN, etc made it onto the machine. It worked really well for personal and school projects, especially team projects (quick ramp up). Anyways, I started to pick up C# to complement my Java knowledge (don't judge me :P), and am interested in working with some of the associated Microsoft equivalents. The machine currently has the Ubuntu install, as well as Windows 7 Ultimate. I do all of my actual development work off my laptop, also running Windows 7 Ultimate. I was wondering what software you would recommend putting on the machine. I’m not actually serving anything off the machine itself, but in Ubuntu I had it doing integration tests with Hudson on every commit, and profiling my applications, etc, etc. The machine would be running headless, and I would remote into it. Here is what I am currently leaning towards / wondering about: Windows 7 Ultimate vs Windows Server 2008 (R2) (no one is really clear why I should go with one over the other) Windows Team Foundation Sharepoint (Never used it before, kind of meh about it) IBM Websphere or Glassfish (Some Java EE web server) SQL Server 2008 A DVCS In order to better control product conflicts / limit resource use, I’m wondering if I should install things into virtual machines (I can get VmWare or Microsoft Virtualization Products) I also plan on installing everything I had running under Linux (it’s almost entirely Java based development software, so it’ll run on both, only reason I went with ubuntu during the year was because the apache build seemed better). I’m primarily looking to become familiar with enterprise software development tools, as well as get something functional that will help my development process. (IE, I’ll still use project and assign tasks even though I might be the only one to assign tasks to, just to practice doing so). Is there any other software / configuration details I should explore? Opinions on my current list? I primarily use C#, Java, and PHP. I'm familiar with ruby, and python as well. Thanks!

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  • casting doubles to integers in order to gain speed

    - by antirez
    Hello all, in Redis (http://code.google.com/p/redis) there are scores associated to elements, in order to take this elements sorted. This scores are doubles, even if many users actually sort by integers (for instance unix times). When the database is saved we need to write this doubles ok disk. This is what is used currently: snprintf((char*)buf+1,sizeof(buf)-1,"%.17g",val); Additionally infinity and not-a-number conditions are checked in order to also represent this in the final database file. Unfortunately converting a double into the string representation is pretty slow. While we have a function in Redis that converts an integer into a string representation in a much faster way. So my idea was to check if a double could be casted into an integer without lost of data, and then using the function to turn the integer into a string if this is true. For this to provide a good speedup of course the test for integer "equivalence" must be fast. So I used a trick that is probably undefined behavior but that worked very well in practice. Something like that: double x = ... some value ... if (x == (double)((long long)x)) use_the_fast_integer_function((long long)x); else use_the_slow_snprintf(x); In my reasoning the double casting above converts the double into a long, and then back into an integer. If the range fits, and there is no decimal part, the number will survive the conversion and will be exactly the same as the initial number. As I wanted to make sure this will not break things in some system, I joined #c on freenode and I got a lot of insults ;) So I'm now trying here. Is there a standard way to do what I'm trying to do without going outside ANSI C? Otherwise, is the above code supposed to work in all the Posix systems that currently Redis targets? That is, archs where Linux / Mac OS X / *BSD / Solaris are running nowaday? What I can add in order to make the code saner is an explicit check for the range of the double before trying the cast at all. Thank you for any help.

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