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  • ViewModel Views relation/link/syncroniztion

    - by mehran
    Third try to describing problem: Try 1: Sunchronizing view model and view Try2: WPF ViewModel not active presenter Try3: I have some class for view models: public class Node : INotifyPropertyChanged { Guid NodeId { get; set; } public string Name { get; set; } } public class Connection: INotifyPropertyChanged { public Node StartNode { get; set; } public Node EndNode { get; set; } } public class SettingsPackModel { public List<Node> Nodes { get; private set; } public List<Connection> Connections { get; private set; } } I also have some templates to displays these models: <DataTemplate DataType="{x:Type vm:Node}">…</DataTemplate> <DataTemplate DataType="{x:Type vm:Connection}"> <my:ConnectionElment StartNodeElment="???" EndNodeElment="???"> </my:ConnectionElment> <DataTemplate> But the problem is that DataTemplate for Connection need reference ot two element of type UIElement , how can I pass these two, how can I fill ??? in above expression?

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  • The Immerman-Szelepcsenyi Theorem

    - by Daniel Lorch
    In the Immerman-Szelepcsenyi Theorem, two algorithms are specified that use non-determinisim. There is a rather lengthy algorithm using "inductive counting", which determines the number of reachable configurations for a given non-deterministic turing machine. The algorithm looks like this: Let m_{i+1}=0 For all configurations C Let b=0, r=0 For all configurations D Guess a path from I to D in at most i steps If found Let r=r+1 If D=C or D goes to C in 1 step Let b=1 If r<m_i halt and reject Let m_{i+1}=m_{i+1}+b I is the starting configuration. m_i is the number of configurations reachable from the starting configuration in i steps. This algorithm only calculates the "next step", i.e. m_i+1 from m_i. This seems pretty reasonable, but since we have nondeterminisim, why don't we just write: Let m_i = 0 For all configurations C Guess a path from I to C in at most i steps If found m_i = m_i + 1 What is wrong with this algorithm? I am using nondeterminism to guess a path from I to C, and I verify reachability I am iterating through the list of ALL configurations, so I am sure to not miss any configuration I respect space bounds I can generate a certificate (the list of reachable configs) I believe I have a misunderstanding of the "power" of non-determinisim, but I can't figure out where to look next. I am stuck on this for quite a while and I would really appreciate any help.

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  • Can't wrap my head around appengine data store persistence

    - by aloo
    Hi, I've run into the "can't operate on multiple entity groups in a single transaction." problem when using APPENGINE FOR JAVA w/ JDO with the following code: PersistenceManager pm = PMF.get().getPersistenceManager(); Query q = pm.newQuery("SELECT this FROM " + TypeA.class.getName() + " WHERE userId == userIdParam "); q.declareParameters("String userIdParam"); List<TypeA> poos = (List<TypeA>) q.execute(userIdParam); for (TypeA a : allTypeAs) { a.setSomeField(someValue); } pm.close(); } The problem it seems is that I can't operate on a multiple entities at the same time b/c they arent in the same entity group while in a transaction. Even though it doesn't seem like I'm in a transaction, appengine generates one because I have the following set in my jdoconfig.xml: <property name="datanucleus.appengine.autoCreateDatastoreTxns" value="true"/> Fine. So far I think I understand. BUT - if I replace TypeA in the above code, with TypeB - I don't get the error. I don't believe there is anything different between type a and type b - they both have the same key structure. They do have different fields but that shouldn't matter, right? My question is - what could possible be different between TypeA and TypeB that they give this different behavior? And consequently what do you I fundamentally misunderstand that this behavior could even exist.... Thanks.

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  • Retrieve OpenId FullName from Google

    - by user294711
    I'm using DotNetOpenAuth lib to work with Google(only) OpenId. And I'm retrieving Email without any problem. But I can't get FullName, it is always null. request.AddExtension(new ClaimsRequest { Email = DemandLevel.Require, FullName = DemandLevel.Require }); ClaimsResponse claimsResponse = relyingPartyResponse.GetExtension<ClaimsResponse>(); if (claimsResponse != null) { var email = claimsResponse.Email; var fullName = claimsResponse.FullName; } I googled this problem and found that: Glad you got it working. Google will not give a full name or nickname for their users. They ONLY give email address, and (I think, but perhaps only on a white list) the timezone. It's not a matter of figuring out how to rig your RP so that it works. Google just won't do it yet. – Andrew Arnott Sep 8 at 14:22 stackoverflow.com/questions/1387438/retrieve-openid-user-information-claims-across-providers But it was in Sep 2009, maybe something was changed from that moment... I've found that in http://code.google.com/apis/accounts/docs/OpenID.html: openid.ax.required -- (required) Specifies the attribute being requested. Valid values include: "country", "email", "firstname", "language", "lastname". To request multiple attributes, set this parameter to a comma-delimited list of attributes. So, my question is how can I get FullName (FirstName, LastName) from Google OpenId?

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  • Deep copy objects from different namespaces

    - by Wasim
    Hi all, I have the following situation: I have class User with the follwing properies : public class User { string user name ; List <Contact> contacts ; List <BookMark> book marks; . . . } I have the same class in a different namespace , with some different properties . BWT , it's the same situation of it's classes (Contact) and (BookMark). I need to make a deep copy of the same properties from the two classes . Actually , I arrive to this situation by having an Entity Framework edmx file . I created the first database (SQL server 2008) from this model . And copied he same edmx file to another project and created the database with SQL CE db. Now I get the first data model objects by WCF service and need to persist them in the local database in my application . The objects are the same but there are some changs because of the modeling issue with a different databse. Do you have any workarround about this assue. Thanks in advance ...

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  • Saving owned/child objects in Hibernate

    - by maxdj
    I'm having a hard time wrapping my head around the way hibernate objects work. Here's a little chunk of what my model looks like: JobOpening: @ManyToMany(fetch=FetchType.EAGER,cascade=CascadeType.ALL) @JoinTable( name="jobOpening_questionSet", joinColumns=@JoinColumn(name="jobOpenings_id"), inverseJoinColumns=@JoinColumn(name="questionSets_id") ) @IndexColumn(name="question_sets_idx",base=0,nullable=false) public List<QuestionSet> getQuestionSets() { return questionSets; } QuestionSet: @ManyToMany(mappedBy="questionSets",fetch=FetchType.EAGER) public Set<JobOpening> getJobOpenings() { return jobOpenings; } @OneToMany(cascade=CascadeType.ALL,fetch=FetchType.EAGER) @IndexColumn(name="questions_idx",base=0) @JoinColumn(name="questionset_id",nullable=false) public List<FormQuestion> getQuestions() { return questions; } FormQuestion: @ManyToOne @JoinColumn(name="questionset_id", insertable=false, updatable=false, nullable=false) @OnDelete(action=OnDeleteAction.CASCADE) public QuestionSet getQuestionSet() { return questionSet; } Now how would I go about, say, modifying a question in the question set, or changing which jobs a questionset is associated with? For example, to edit a question in a questionset, I imagine I should be able to just get the question via its id, change some values, and merge() it back in, but this doesn't work. I'm using Hibernate from Spring (appfuse), usually as detached objects.

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  • Silverlight datagrid fails to display data.

    - by Jekke
    I have a datagrid defined in my project's XAML: <data:DataGrid IsReadOnly="True" Grid.Row="1" Grid.Column="1" x:Name="gridOfferings" Margin="10,10,10,10" AutoGenerateColumns="False"> <data:DataGrid.Columns> <data:DataGridTextColumn Binding="{Binding Trader}" DisplayIndex="0" Header="Trader" Width="Auto" FontSize="11"/> <data:DataGridTextColumn Binding="{Binding Product}" DisplayIndex="1" Header="Product" Width="Auto" FontSize="11"/> </data:DataGrid.Columns> </data:DataGrid> I bind it to a List< of custom objects: public MainPage() { InitializeComponent(); _Rows = new List<OfferingRowData>(); _Rows.Add(new OfferingRowData() { Trader = "Kameilya Loenstein", Product = "American Consolidated AAA", Price = 24.95, OfferingMade = DateTime.Now }); _Rows.Add(new OfferingRowData() { Trader = "Bill Foobar", Product = "IBM Mid-Atlantic Exotic", Price = 204.90, OfferingMade = DateTime.Now.AddMinutes(-3) }); gridOfferings.ItemsSource = _Rows; } When it shows up on the page, the column headers appear, but none of the data does. What am I doing wrong?

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  • unique items from an observableArray of object properties

    - by Joe
    I'm trying to extract unique properties from a knockout.js observableArray of objects, to populate a drop menu. Being new to knockout, I'm really struggling with this! I want to iterate over a contacts list, and populate a drop menu with a unique value from each person object within the observableArray. So in my code example below, I wish to populate my drop menu with a list of people 'type' - family, friend etc. Looking on Google, I found a similar function, but it does not return any values, even if I console.log the results? //dummy data more rows in actual code... var people = [ { name: "Contact 1", address: "1, a street, a town, a city, AB12 3CD", tel: "0123456789", email: "[email protected]", type: "family" }, { name: "Contact 2", address: "1, a street, a town, a city, AB12 3CD", tel: "0123456789", email: "[email protected]", type: "friend" } ]; function ContactsViewModel(people) { var self = this; self.contacts = ko.observableArray(people); self.uniqueSelect = ko.dependentObservable(function() { return( ko.utils.arrayGetDistinctValues(self.contacts().type).sort()); }, self); }; ko.applyBindings(new ContactsViewModel()); And HTML template <p>Show me: <select data-bind="options: ContactsViewModel.uniqueSelect"></select></p> Any help appreciated, as a noob I'm lost! Thanks

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  • PostgreSQL, Foreign Keys, Insert speed & Django

    - by Miles
    A few days ago, I ran into an unexpected performance problem with a pretty standard Django setup. For an upcoming feature, we have to regenerate a table hourly, containing about 100k rows of data, 9M on the disk, 10M indexes according to pgAdmin. The problem is that inserting them by whatever method literally takes ages, up to 3 minutes of 100% disk busy time. That's not something you want on a production site. It doesn't matter if the inserts were in a transaction, issued via plain insert, multi-row insert, COPY FROM or even INSERT INTO t1 SELECT * FROM t2. After noticing this isn't Django's fault, I followed a trial and error route, and hey, the problem disappeared after dropping all foreign keys! Instead of 3 minutes, the INSERT INTO SELECT FROM took less than a second to execute, which isn't too surprising for a table <= 20M on the disk. What is weird is that PostgreSQL manages to slow down inserts by 180x just by using 3 foreign keys. Oh, disk activity was pure writing, as everything is cached in RAM; only writes go to the disks. It looks like PostgreSQL is working very hard to touch every row in the referred tables, as 3MB/sec * 180s is way more data than the 20MB this new table takes on disk. No WAL for the 180s case, I was testing in psql directly, in Django, add ~50% overhead for WAL logging. Tried @commit_on_success, same slowness, I had even implemented multi row insert and COPY FROM with psycopg2. That's another weird thing, how can 10M worth of inserts generate 10x 16M log segments? Table layout: id serial primary, a bunch of int32, 3 foreign keys to small table, 198 rows, 16k on disk large table, 1.2M rows, 59 data + 89 index MB on disk large table, 2.2M rows, 198 + 210MB So, am I doomed to either drop the foreign keys manually or use the table in a very un-Django way by defining saving bla_id x3 and skip using models.ForeignKey? I'd love to hear about some magical antidote / pg setting to fix this.

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  • Timeout error occurred trying to start MySQL Daemon. CentOS 5

    - by epema
    I ran into troubles with MySQL on my CentOS. I had some problems and backed up my database and removed mysql with all dependencies. After that I ran reinstalled: yum groupinstall "MySQL Database" Installed without errors. Running the mysql daemon: service mysqld start Timeout error occurred trying to start MySQL Daemon. Starting MySQL: [FAILED] I also ran # /usr/bin/mysql_install_db --user=mysql Installing MySQL system tables... 120112 1:49:44 [ERROR] Error message file '/usr/share/mysql/english/errmsg.sys' had only 480 error messages, but it should contain at least 481 error messages. Check that the above file is the right version for this program! 120112 1:49:44 [ERROR] Aborting Installation of system tables failed! Examine the logs in /var/lib/mysql for more information. You can try to start the mysqld daemon with: /usr/libexec/mysqld --skip-grant & and use the command line tool /usr/bin/mysql to connect to the mysql database and look at the grant tables: shell> /usr/bin/mysql -u root mysql mysql> show tables Try 'mysqld --help' if you have problems with paths. Using --log gives you a log in /var/lib/mysql that may be helpful. The latest information about MySQL is available on the web at http://www.mysql.com Please consult the MySQL manual section: 'Problems running mysql_install_db', and the manual section that describes problems on your OS. Another information source is the MySQL email archive. Please check all of the above before mailing us! And if you do mail us, you MUST use the /usr/bin/mysqlbug script! Checking the logs: less /var/log/mysqld.log Log file is empty. I don't even know how to debug it and not sure what to do. Any recommendations? Thank you

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  • How to write a Criteria Query when there's an <any> association

    - by Bevan
    I'm having some trouble constructing the correct Criteria to do a particular query - after an afternoon of consultation with Professor Google, I'm hoping that someone can point me in the right direction. I have two entities of interest: OutputTsDef and NamedAttribute What I'm trying to do is to find all OutputTsDef that have a particular NamedAttribute value. I can write a detached Criteria to find all NamedAttributes that have a given name and value: var attributesCriteria = DetachedCriteria.For<INamedAttribute>() .Add(Expression.Eq("Name", "some name")) .Add(Expression.Eq("Value", "some value")); How do I inject this in to a query for OutputTsDef to restrict the results? var criteria = nHibernateSession.CreateCriteria(typeof(IOutputTsDefEntity)); // What do I write here? var results = criteria.List(); NamedAttribute looks like this - note the use of [Any] as we can have NamedAttributes on many kinds of entity. [AttributeIdentifier("DbKey", Name = "Id.Column", Value = "NamedAttributeID")] [Class(Table = "NamedAttributes")] public class NamedAttribute : BusinessEntity, INamedAttribute { [Any(0, Name = "Entity", MetaType = "System.String", IdType = "System.Int32")] [MetaValue(1, Class = "Sample.OutputTsDef, Sample.Entities", Value = "OTD")] [MetaValue(2, Class = "Sample.OutputTimeSeriesAttributesEntity, Sample.Entities", Value = "OTA")] [Column(3, Name = "OwnerType")] [Column(4, Name = "OwnerKey")] public virtual IBusinessEntity Entity { get; set; } [Property(Column = "Name")] public virtual string Name { get; set; } [Property(Column = "Value")] public virtual string Value { get; set; } ... omitted ... } In regular SQL, I'd just include an extra "where" clause like this: where OutputTsDefId in ( select distinct OwnerKey from NamedAttributes where Name = ? and Value = ? and OwnerType = 'OTD' ) What am I missing? (Question also posted to the NHUsers mailing list - I'll copy any useful information from there, here.)

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  • find the children in jquery

    - by armin etemadi
    i have a tree structure,there is an unordered list(ul) in that tree.i have li items in it,and in that li items it could be a span or an ul list. this is one part of my codes : <li id="main_li"> <div class="first_division"></div> <span>products</span> <ul style="display: block;"> <li> <div class="division1"></div> <span>products_cat_1</span> <ul style="display: none;"> <li> <span>products_cat_1_milk</span> </li> </ul> </li> <li> <span>products_yoghurt</span> </li> <li> <span>products_butter</span> </li> </ul> </li> i want to access li elements in ul tag where the parent li id is "main_li",i want to get it done by clicking on the span within li. how can i do this with jquery?

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  • Web application architecture, and application servers?

    - by seanieb
    Hi, I'm building a web application, and I need to use an architecture that allows me to run it on two servers. The application scrapes information from other sites periodically, and on input from the end user. To do this I'm using Php+curl to scrape the information, Php or python to parse it and store the results in a MySQLDB. Then I will use Python to run some algorithms on the data, this will happen both periodically and on input from the end user. I'm going to cache some of the results in the MySQL DB and sometimes if it is specific to the user, skip storing the data and serve it to the user. I'm think of using Php for the website front end on a separate web server, running the Php spider, MySQL DB and python on another server. As you can see I'm fairly clueless. I'm familiar with using Php, MySQL and the basics of Python, but bringing this all together using something more complex than a cron job is new to me. How do go about implementing this? What frame work(s) should I use? Is MVC a good architecture for this? (I'm new to MVC, architectures etc.) Is Cakephp a good solution? If so will I be able to control and monitor the Python code using it?

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  • Using PLINQ to calculate and update values within the enclosure does not work

    - by Keith
    I recently needed to do a running total on a report. Where for each group, I order the rows and then calculate the running total based on the previous rows within the group. Aha! I thought, a perfect use case for PLINQ! However, when I wrote up the code, I got some strange behavior. The values I was modifying showed as being modified when stepping through the debugger, but when they were accessed they were always zero. Sample Code: class Item { public int PortfolioID; public int TAAccountID; public DateTime TradeDate; public decimal Shares; public decimal RunningTotal; } List<Item> itemList = new List<Item> { new Item { PortfolioID = 1, TAAccountID = 1, TradeDate = new DateTime(2010, 5, 1), Shares = 5.335m, }, new Item { PortfolioID = 1, TAAccountID = 1, TradeDate = new DateTime(2010, 5, 2), Shares = -2.335m, }, new Item { PortfolioID = 2, TAAccountID = 1, TradeDate = new DateTime(2010, 5, 1), Shares = 7.335m, }, new Item { PortfolioID = 2, TAAccountID = 1, TradeDate = new DateTime(2010, 5, 2), Shares = -3.335m, }, }; var found = (from i in itemList where i.TAAccountID == 1 select new Item { TAAccountID = i.TAAccountID, PortfolioID = i.PortfolioID, Shares = i.Shares, TradeDate = i.TradeDate, RunningTotal = 0 }); found.AsParallel().ForAll(x => { var prevItems = found.Where(i => i.PortfolioID == x.PortfolioID && i.TAAccountID == x.TAAccountID && i.TradeDate <= x.TradeDate); x.RunningTotal = prevItems.Sum(s => s.Shares); }); foreach (Item i in found) { Console.WriteLine("Running total: {0}", i.RunningTotal); } Console.ReadLine(); If I change the select for found to be .ToArray(), then it works fine and I get calculated reuslts. Any ideas what I am doing wrong?

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  • accordion effect

    - by Veejay
    There are so many 'huge' accordion scripts around and I am confused. Can anyone suggest me a simple code to turn this list into a accordion panel. To start with, only the 'Sports' list will be visible. Then when the user clicks on either Technology or Latest, the Sports will hide and the one clicked will show up and so on.. <ul id="accordion"> <li>Sports</li> <ul> <li><a href="#">Golf</a></li> <li><a href="#">Cricket</a></li> <li><a href="#">Football</a></li> </ul> <li>Technology</li> <ul> <li><a href="#">iPhone</a></li> <li><a href="#">Facebook</a></li> <li><a href="#">Twitter</a></li> </ul> <li>Latest</li> <ul> <li><a href="#">Obama</a></li> <li><a href="#">Iran Election</a></li> <li><a href="#">Health Care</a></li> </ul> </ul>

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  • Advantages/Disadvantages of AIR vs Flex/Web

    - by Lizzan
    Hi all, I'm tasked with writing an application for placing and connecting objects (sort of like a room planner where you can place furniture). I've made a demo using Flash Builder 4 and built it for AIR as a desktop app. Now the client wants the full app, but they and I am unsure whether to continue building it as an AIR app or transform it to a web application using Flex. I tried making a simple conversion of the AIR app to a web app, and most things worked but not all. The things that don't work seem to be simple bugs, though, not complete lack of capability. The capabilities that I'm going to need (except for the modelling) are: Printing of the finished image + a list of the furniture that has been placed A way to save and retrieve finished plans A way to export the list of furniture to Excel format Handling a whole slew of data about the different objects Only the printing has been implemented so far, and seems to work in the web app as well. What advantages/disadvantages are there with the two approaches? Are any of the capabilities I need much worse (or even impossible) to implement in either approach?

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  • Loading enumerations from database

    - by Mosh
    Hello, I have a problem with mapping .NET enumerations to database tables. Imagine I have a table called Statuses with the following values: StatusID | Name 1 Draft 2 Ready ... ... In the application layer, I can either use a Repository to get all Statuses as an IList object. However, the problem with this approach is that I cannot reference a certain status in my business logic. For example, how can I implement something like this? if (myObject.Status is Ready) do this else if (myObject.Status is Draft) do that... Since the statuses are loaded dynamically, I cannot tell for sure what particular Status object in the List represents the Draft or Ready status. Alternatively, I could just use an enumeration like public enum Statuses { Draft, Ready }; Then I could easily use an enumeration in my business logic. if (myObject.Status == Statuses.Draft) // do something... However, the problem with this approach is that every time the user wants to modify the list of Statuses (adding a new status, or renaming an existing status) the application has to be re-compiled. We cannot load the statuses dynamically from the database. Has anyone else come across a similar situation? Any solutions/patterns? Cheers, Mosh

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  • what are all the Optimize tricks that you know for asp.net code ?

    - by Aristos
    After some time of many code programming on asp.net, I discover the very big speed different between string and StringBuilder. I know that is very common and known but I just mention it for start. The second think that I have found to speed up the code, is to use the const, and not the static, for declare my configuration constants value (especial the strings). With the const, the compiler not create new object, but just place the value, on the point that you have ask it, but with the static declaration, is create a new memory object and keep its on the memory. My third trick, is when I search for string, I use hash values, and not the string itself. For example, if I need a List<string SomeValues, and place inside strings that I need to search them, I prefer to use List<int SomeHashValue, and I use the hash value to locate the strings. My forth thought that I was wandering, is if is better to place big strings in one line, or separate them in different lines with the + symbol to be more easy to read out. I make some tests and see that the compiler make a good job is some split the string, in many lines, using the + symbol. What other tricks/tips do you know and use on your programming to make it run faster, and maybe use less memory. Well I know, that some times, to make something run faster, you need more memory, more cache. My priority is on speed. Because Speed Counts.

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  • Querying datetime.datetime on appengine acts different then dev server help!

    - by Alon Carmel
    Hey, I'm having some trouble with stuff that work locally and dont work on the app engine python environment: Basically, i want to get a program from an epg between ranges of date and time. i know i cannot do two where < so i saw a suggestion to save the dates as list as datetime.datetime which i did. [datetime.datetime(2010, 5, 10, 14, 25), datetime.datetime(2010, 5, 10, 15, 0)] This is ok. but when i try to compare to it: progranon = get_object(Programs2Channel, 'channel_id =', channelobj.key(), 'endstartdate >', programstart_minex, 'endstartdate <', programstart_minex ) This for some reason works locally, but fails to retrieve the data on the app engine. *Im using Google app engine django patch which uses the get_object to retrieve data in transactions. Please help. Here are more details: this is the LIST: [datetime.datetime(2010, 5, 13, 10, 45), datetime.datetime(2010, 5, 13, 11, 30)] #this is the query: programstart = ""+year+"-"+month+"-"+day+" "+hour+":"+minute programstart_minex = datetime.strptime(programstart, "%Y-%m-%d %H:%M") progranon = Programs2Channel.gql('WHERE channel_id = :channelid AND endstartdate > :programstartx AND endstartdate < :programstartx',channelid = channelobj.key(),programstartx=programstart_minex).get()

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  • Doubts about .NET Garbage Collector

    - by Smjert
    I've read some docs about the .NET Garbage Collector but i still have some doubts (examples in C#): 1)Does GC.Collect() call a partial or a full collection? 2)Does a partial collection block the execution of the "victim" application? If yes.. then i suppose this is a very "light" things to do since i'm running a game server that uses 2-3GB of memory and i "never" have execution stops (or i can't see them..). 3)I've read about GC roots but still can't understand how exactly they works. Suppose that this is the code (C#): MyClass1: [...] public List<MyClass2> classList = new List<MyClass2>(); [...] Main: main() { MyClass1 a = new MyClass1(); MyClass2 b = new MyClass2(); a.classList.Add(b); b = null; DoSomeLongWork(); } Will b ever be eligible to be garbage collected(before the DoSomeLongWork finishes)? The reference to b that classList contains, can it be considered a root? Or a root is only the first reference to the instance? (i mean, b is the root reference because the instantiation happens there).

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  • populatin jComBobox with data from a db tbl(table) column

    - by mnmyles
    Hi guyz? I have a JComboBox which i have named "venue_JCB" i want to load details from a tbl column on form load at the initcomponets() i have declared the method "accessDBinit() ;" and after the initComponets() i have implemented the accessDBinit(); method as follows: ================================code============================ void accessDBinit() //Get Student List in the List Box { try { sql = "SELECT classLevel FROM class_session ORDER BY classLevel"; java.lang.Class.forName("com.mysql.jdbc.Driver"); Connection con2=DriverManager.getConnection("jdbc:mysql:///coast","root",""); Statement stmt2 = (Statement)con2.createStatement(); boolean hasResults = stmt2.execute(sql); if(hasResults) { ResultSet rs2 = stmt2.getResultSet(); if(rs2!=null) { displayResultsinit(rs2); } db.stmt.close(); } } catch(Exception e) { System.out.println(e+"Error in connection"); } } void displayResultsinit(ResultSet r) throws SQLException { ResultSetMetaData rmeta = r.getMetaData(); int numColumns=rmeta.getColumnCount(); while(r.next()) { for(int i=1;i<=numColumns;++i) { if(i<=numColumns) { venue_JCB.addItem(r.getString(i)); } } } } ====================================end of code=================================== the method works (Populate the combobox) but at the output bar i get the following on form load and also whenever i select a component from the combobox ======= error===== java.lang.NullPointerExceptionError in connection could some one please tell me where i am going wrong with the method? Thanks in advance regards Malachi

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  • Creating a Multiwindowed Cocoa Program - Launching Procedure Suggestions?

    - by Jeffrey Kern
    I'm porting an application I developed in Visual Studio 2008 over to Cocoa. I'm currently doing a 'learn-as-you-go' approach to Cocoa, so I can experiment with different ideas and techniques in smaller, simpler projects and eventually combine them into one big application. My program logic is as follows (in a dumbed-down sense). Items in the list are mandated by my boss. Application is started 1a. Verify CD program is in drive. Verify license. If found and is valid, skip to step 7 Display license agreement. Display serial number prompt. Verify and save serial number. Hide all prior windows. Load main application window Intercept requests and commands from main application window, including making a duplicate main application window Exit program when requested by user What would the best bet be for this type of application? From another question I asked, I found out that I should keep the 'main application' window in a separate XIB file from the rest, because I might need to clone and interact with it. I know that since Cocoa and Objective-C is based off of C, there is a Main method somewhere. But what would you all suggest as a starting place for an application like this?

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  • 500 Worker Threads, what kind of thread pool?

    - by Submerged
    I am wondering if this is the best way to do this. I have about 500 threads that run indefinitely, but Thread.sleep for a minute when done one cycle of processing. ExecutorService es = Executors.newFixedThreadPool(list.size()+1); for (int i = 0; i < list.size(); i++) { es.execute(coreAppVector.elementAt(i)); //coreAppVector is a vector of extends thread objects } The code that is executing is really simple and basically just this class aThread extends Thread { public void run(){ while(true){ Thread.sleep(ONE_MINUTE); //Lots of computation every minute } } } I do need a separate threads for each running task, so changing the architecture isn't an option. I tried making my threadPool size equal to Runtime.getRuntime().availableProcessors() which attempted to run all 500 threads, but only let 8 (4xhyperthreading) of them execute. The other threads wouldn't surrender and let other threads have their turn. I tried putting in a wait() and notify(), but still no luck. If anyone has a simple example or some tips, I would be grateful! Well, the design is arguably flawed. The threads implement Genetic-Programming or GP, a type of learning algorithm. Each thread analyzes advanced trends makes predictions. If the thread ever completes, the learning is lost. That said, I was hoping that sleep() would allow me to share some of the resources while one thread isn't "learning"

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  • Is there a workaround for Linux mono's refusal to acknowledge that I have resized the columns of my

    - by fantius
    When I resize a column, it does not redraw the data with the updated alignment. I've tried Invalidating, Refreshing, and a few other things. Nothing has worked. Does anyone know a workaround? I have not tried this in mono for Windows. To see what I mean, drop this control on a form, and run it in mono for Linux: using System; using System.Collections.Generic; using System.Text; using System.Windows.Forms; using System.Drawing; class MyListView : ListView { private readonly List<ListViewItem> items_ = new List<ListViewItem>(); public MyListView() { VirtualMode = true; Columns.Add("Col 1"); Columns.Add("Col 2"); Columns.Add("Col 3"); Add(new ListViewItem(new[] { "a", "b", "c" })); Add(new ListViewItem(new[] { "a", "b", "c" })); Add(new ListViewItem(new[] { "a", "b", "c" })); Add(new ListViewItem(new[] { "a", "b", "c" })); Add(new ListViewItem(new[] { "a", "b", "c" })); } protected override void OnRetrieveVirtualItem(RetrieveVirtualItemEventArgs e) { e.Item = items_[e.ItemIndex]; base.OnRetrieveVirtualItem(e); } public void Add(ListViewItem item) { items_.Add(item); VirtualListSize = items_.Count; } protected override void OnDrawColumnHeader(DrawListViewColumnHeaderEventArgs e) { e.DrawText(); base.OnDrawColumnHeader(e); } protected override void OnDrawSubItem(DrawListViewSubItemEventArgs e) { var text = ((ListViewItem.ListViewSubItem)e.SubItem).Text; using (var brush = new SolidBrush(e.SubItem.ForeColor)) { e.Graphics.DrawString(text, Font, brush, e.Bounds); } base.OnDrawSubItem(e); } protected override void OnColumnWidthChanged(ColumnWidthChangedEventArgs e) { base.OnColumnWidthChanged(e); Invalidate(true); // Nope, that didn't work Refresh(); // Nope, that didn't work } }

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  • Which SQL statements to execute with intersection / junction tables

    - by user1455103
    Here a simplified database layout One condo can hold multiple properties (flats, garage boxes, etc) - 1->n relationship One owner can have multiple properties in the same condo and properties can have more than one owner (m->n changed to 1->n with the junction table) One condo can have multiple owners - 1->n Some additional clarification: A owner is a member of a condo. A condo is made of properties belonging to owners BUT a owner is not linked to a property directly (there can be no relation between a property and a owner for a certain time BUT there will ALWAYS be a relation between a owner and a condo). Reason for this: the agent managing the condo will first create a list of owners and a list of properties. It is only later thet he will "link" each property to one or multiple owners (or inversely) I'm quite new to SQL. What SQL statements should I execute to: SELECT, for a specific condo (WHERE condition), the properties and their respective owners (all properties should be listed even if owners are null) SELECT, for a specific condo (WHERE condition), the owners along with their properties (all owners should be listed even if properties are null) UPDATE / DELETE existing owners (I'm uncertain about how to handle the operation for the junction tables. Should I first check if there is an entry in the junction table or not ?) UPDATE / DELETE existing properties (same concern) INSERT new owners (should I use two different SQL statements depending if the owner should be linked to a property or NOT - IF condition ?) INSERT new properties (same question as above) Could you be as clear and generic as possible so that it can be reused ? :-)

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