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  • asp.net mvc default model binding problem

    - by csetzkorn
    I have some problems with ASP.NET MVC’s default model binder. The View contains HTML like this: <input name="SubDTO[0].Id" value="1" type="checkbox"> <input name="SubDTO[1].Id" value="2" type="checkbox"> This is my simplified ‘model’: public class SubDTO { public virtual string Id { get; set; } } public class DTO { public List<SubDTO> SubDTOs { get; set; } public DTO() { SubDTOs = new List< SubDTO>(); } } All this works fine if the user selects at least the first checkbox (SubDTO[0].Id). The controller ‘receives’ a nicely initialised/bound DTO. However, if the first check box is not selected but only, for example, SubDTO[1].Id the object SubDTOs is null. Can someone please explain this ‘strange’ behaviour and how to overcome it? Thanks. Best wishes, Christian

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  • Change background colour of individual elements on the fly

    - by John
    Hi, Is there a way in CSS or JQuery where I can dynamically change the background of li tags so they get slightly lighter for each element until it gets to white. For example say I had a list of 10 li elements. The first would have a red (#ff0000) background, the next one would then be a lighter shade of red, and so on and so on until we got to the last one which would have a background of white (#FFFFFF) The list can be any length and i just want the background colour to go from one colour e.g. red to another colour e.g. white. My site uses JQuery so if I have to use that I don't mind. Thanks

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  • WPF Datagrid items binding problem

    - by gencay
    I get a problem while displaying a List in WPF-Datagrid. When I do this line ... DocumentList dt = new DocumentList(fileWordList, fileUriType, fileUri, cosineSimilarityRatio, diceSimilarityRatio, extendedJaccardSimilarityRatio); documentList.Add(dt); ... dataGrid1.Items.Add(dt); ... It creates an empty row into dataGrid1 and no text is shown there. my xaml implementation is this: <GroupBox Canvas.Left="-0.003" Canvas.Top="0" Header="Display Results" Height="427.5" Name="groupBox2" Width="645.56"> <toolkit:DataGrid Canvas.Left="137.5" Canvas.Top="240" Height="392" Name="dgrDocumentList" Width="627" ItemsSource="{Binding DocumentList }"> <toolkit:DataGrid.Columns> <toolkit:DataGridTextColumn Header="Type" Binding="{Binding type}" IsReadOnly="True"> </toolkit:DataGridTextColumn> <toolkit:DataGridHyperlinkColumn Header="Uri" Binding="{Binding path}" IsReadOnly="True"> </toolkit:DataGridHyperlinkColumn> <toolkit:DataGridTextColumn Header="Cosine" Binding="{Binding cos}" IsReadOnly="True"> </toolkit:DataGridTextColumn> <toolkit:DataGridTextColumn Header="Dice" Binding="{Binding dice}" IsReadOnly="True"> </toolkit:DataGridTextColumn> <toolkit:DataGridTextColumn Header="Jaccard" Binding="{Binding jaccard}" IsReadOnly="True"> </toolkit:DataGridTextColumn> </toolkit:DataGrid.Columns> </toolkit:DataGrid> </GroupBox> and my DocumentList class class DocumentList { public List<WordList> wordList; public string type; public string path; public double cos; public double dice; public double jaccard; //public static string title; public DocumentList(List<WordList> wordListt, string typee, string pathh, double sm11, double sm22, double sm33) { type = typee; wordList = wordListt; path = pathh; cos = sm11; dice = sm22; jaccard = sm33; } I would like to do that: When i add a new element into documentList instance, would like to see the results on data grid. Thank you in advance.

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  • C# SQL Parameter Errors in Loops

    - by jakesankey
    Please help me out with this. I have this small application to load txt files into a sql db and it works fine with sqlite. When I ported to SQL I started getting 'parameter already declared' errors.. If anyone can help me reorganize this code, it would be great! I need to get the parameter definitions outside of the loops or something.. using System; using System.Data; using System.Data.SQLite; using System.IO; using System.Text.RegularExpressions; using System.Threading; using System.Collections.Generic; using System.Linq; using System.Data.SqlClient; namespace JohnDeereCMMDataParser { internal class Program { public static List<string> GetImportedFileList() { List<string> ImportedFiles = new List<string>(); using (SqlConnection connect = new SqlConnection(@"Server=FRXSQLDEV;Database=RX_CMMData;Integrated Security=YES")) { connect.Open(); using (SqlCommand fmd = connect.CreateCommand()) { fmd.CommandText = @"SELECT FileName FROM Import;"; fmd.CommandType = CommandType.Text; SqlDataReader r = fmd.ExecuteReader(); while (r.Read()) { ImportedFiles.Add(Convert.ToString(r["FileName"])); } } } return ImportedFiles; } private static void Main(string[] args) { using (SqlConnection con = new SqlConnection(@"Server=FRXSQLDEV;Database=RX_CMMData;Integrated Security=YES")) { con.Open(); using (SqlCommand insertCommand = con.CreateCommand()) { Console.WriteLine("Connecting to SQL server..."); SqlCommand cmdd = con.CreateCommand(); string[] files = Directory.GetFiles(@"C:\Documents and Settings\js91162\Desktop\", "R.txt*", SearchOption.AllDirectories); insertCommand.Parameters.Add(new SqlParameter("@FeatType", DbType.String)); insertCommand.Parameters.Add(new SqlParameter("@FeatName", DbType.String)); insertCommand.Parameters.Add(new SqlParameter("@Value", DbType.String)); insertCommand.Parameters.Add(new SqlParameter("@Actual", DbType.Decimal)); insertCommand.Parameters.Add(new SqlParameter("@Nominal", DbType.Decimal)); insertCommand.Parameters.Add(new SqlParameter("@Dev", DbType.Decimal)); insertCommand.Parameters.Add(new SqlParameter("@TolMin", DbType.Decimal)); insertCommand.Parameters.Add(new SqlParameter("@TolPlus", DbType.Decimal)); insertCommand.Parameters.Add(new SqlParameter("@OutOfTol", DbType.Decimal)); List<string> ImportedFiles = GetImportedFileList(); foreach (string file in files.Except(ImportedFiles)) { var FileNameExt1 = Path.GetFileName(file); cmdd.Parameters.Add(new SqlParameter("@FileExt", FileNameExt1)); cmdd.CommandText = @" IF (EXISTS (SELECT * FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA = 'RX_CMMData' AND TABLE_NAME = 'Import')) BEGIN SELECT COUNT(*) FROM Import WHERE FileName = @FileExt; END"; int count = Convert.ToInt32(cmdd.ExecuteScalar()); con.Close(); con.Open(); if (count == 0) { Console.WriteLine("Parsing CMM data for SQL database... Please wait."); insertCommand.CommandText = @" INSERT INTO Import (FeatType, FeatName, Value, Actual, Nominal, Dev, TolMin, TolPlus, OutOfTol, PartNumber, CMMNumber, Date, FileName) VALUES (@FeatType, @FeatName, @Value, @Actual, @Nominal, @Dev, @TolMin, @TolPlus, @OutOfTol, @PartNumber, @CMMNumber, @Date, @FileName);"; string FileNameExt = Path.GetFullPath(file); string RNumber = Path.GetFileNameWithoutExtension(file); string RNumberE = RNumber.Split('_')[0]; string RNumberD = RNumber.Split('_')[1]; string RNumberDate = RNumber.Split('_')[2]; DateTime dateTime = DateTime.ParseExact(RNumberDate, "yyyyMMdd", Thread.CurrentThread.CurrentCulture); string cmmDate = dateTime.ToString("dd-MMM-yyyy"); string[] lines = File.ReadAllLines(file); bool parse = false; foreach (string tmpLine in lines) { string line = tmpLine.Trim(); if (!parse && line.StartsWith("Feat. Type,")) { parse = true; continue; } if (!parse || string.IsNullOrEmpty(line)) { continue; } Console.WriteLine(tmpLine); foreach (SqlParameter parameter in insertCommand.Parameters) { parameter.Value = null; } string[] values = line.Split(new[] { ',' }); for (int i = 0; i < values.Length - 1; i++) { SqlParameter param = insertCommand.Parameters[i]; if (param.DbType == DbType.Decimal) { decimal value; param.Value = decimal.TryParse(values[i], out value) ? value : 0; } else { param.Value = values[i]; } } } insertCommand.Parameters.Add(new SqlParameter("@PartNumber", RNumberE)); insertCommand.Parameters.Add(new SqlParameter("@CMMNumber", RNumberD)); insertCommand.Parameters.Add(new SqlParameter("@Date", cmmDate)); insertCommand.Parameters.Add(new SqlParameter("@FileName", FileNameExt)); // insertCommand.ExecuteNonQuery(); } } Console.WriteLine("CMM data successfully imported to SQL database..."); } con.Close(); } } } } FYI - the PartNumber, CMMNumber, Date, etc at the bottom are pulled from the file name and I need it in the table next to each respective record.

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  • Get notified/receive explicit intents when an activity starts

    - by qtips
    Hi, I am developing an application than gets notified when an activity chosen by a user is started. For this to work, the best approach would be to register a broadcastreceiver for ACTION_MAIN explicit intents, which as far as I know doesn't work (because these intents have specific targets). Another, probably less efficient approach, is to use the system ActivityManager and poll on the getRunningTask() which returns a list of all running tasks at the moment. The polling can be done by a background service. By monitoring the changes in this list, I can see whether an activity is running or not, so that my application can get notified. The downside is ofcourse the polling. I have not tried this yet, but I think that this last approach will probably work. Does anyone know of a better approach(es) or suggestions which are less intensive?

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  • LINQ Except operator and object equality

    - by Abhijeet Patel
    Here is an interesting issue I noticed when using the Except Operator: I have list of users from which I want to exclude some users: The list of users is coming from an XML file: The code goes like this: interface IUser { int ID { get; set; } string Name { get; set; } } class User: IUser { #region IUser Members public int ID { get; set; } public string Name { get; set; } #endregion public override string ToString() { return ID + ":" +Name; } public static IEnumerable<IUser> GetMatchingUsers(IEnumerable<IUser> users) { IEnumerable<IUser> localList = new List<User> { new User{ ID=4, Name="James"}, new User{ ID=5, Name="Tom"} }.OfType<IUser>(); var matches = from u in users join lu in localList on u.ID equals lu.ID select u; return matches; } } class Program { static void Main(string[] args) { XDocument doc = XDocument.Load("Users.xml"); IEnumerable<IUser> users = doc.Element("Users").Elements("User").Select (u => new User { ID = (int)u.Attribute("id"), Name = (string)u.Attribute("name") } ).OfType<IUser>(); //still a query, objects have not been materialized var matches = User.GetMatchingUsers(users); var excludes = users.Except(matches); // excludes should contain 6 users but here it contains 8 users } } When I call User.GetMatchingUsers(users) I get 2 matches as expected. The issue is that when I call users.Except(matches) The matching users are not being excluded at all! I am expecting 6 users ut "excludes" contains all 8 users instead. Since all I'm doing in GetMatchingUsers(IEnumerable users) is taking the IEnumerable and just returning the IUsers whose ID's match( 2 IUsers in this case), my understanding is that by default "Except" will use reference equality for comparing the objects to be excluded. Is this not how "Except" behaves? What is even more interesting is that if I materialize the objects using .ToList() and then get the matching users, and call "Except", everything works as expected! Like so: IEnumerable users = doc.Element("Users").Elements("User").Select (u = new User { ID = (int)u.Attribute("id"), Name = (string)u.Attribute("name") } ).OfType().ToList(); //explicity materializing all objects by calling ToList() var matches = User.GetMatchingUsers(users); var excludes = users.Except(matches); // excludes now contains 6 users as expected I don't see why I should need to materialize objects for calling "Except" given that its defined on IEnumerable? Any suggesstions / insights would be much appreciated.

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  • display a confirmation popup on button click based on condition

    - by Raaz
    I have a p:commandButton on click of which I need to add a few values to a list. In my managed bean, I'm validating the value that has to be added, and if it validates to false, I have to display a confirmation popup. This is my code - <p:commandButton id="add" value="Add" type="submit" action="#{bean.doAdd}" ajax="false" update=":List"/> And in the bean, on click of the "Add" button, public String doAdd() throws Exception { if(response != null) { if(keyList.contains(response)) { if(!responseList.contains(response)) { responseList.add(response); } } else { //Have to display confirmation popup. } response = ""; } return response; } I'm using jsf 2.0 and primefaces 3.0. Can someone please tell me how to display the popup from the bean?

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  • Pass in the object a java class is embedded in as a parameter.

    - by Leif Andersen
    I'm building an android application, which has a list view, and in the list view, a click listener, containing an onItemClick method. So I have something like this: public class myList extends ListActivity { @Override public void onCreate(Bundle savedInstanceState) { getListView().setOnItemClickListener(new OnItemClickListener() { public void onItemClick(AdapterView<?> parent, View view, int position, long id) { /* Do something*/ } } } Normally, this works fine. However, many times I find myself needing too preform an application using the outer class as a context. thusfar, I've used: parent.getContext(); to do this, but I would like to know, is that a bad idea? I can't really call: super because it's not really a subclass, just an embedded one. So is there any better way, or is that considered cosure? Also, if it is the right way, what should I do if the embedded method doesn't have a parameter to get the outside class? Thank you.

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  • Replicating iPhone Calendar View Lame?

    - by John Wright
    I am building an iPhone app that will need to display info primarily in a calendar view. Users will need to be able to search for entries and view them by day, month or in a list view. It seems like the built-in calendar type interface is ideal for my app. So I could build a similar calendar with 3 buttons at the bottom for list/day/month view as well as a button for today, in short a very similar interface to the built in iPhone calendar with different colors primarily. However, if I replicate it am I a) a lame copycat for replicating the built-in interface or smart for using a well-known iPhone metaphor and b) in danger of having my app rejected?

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  • Excel VBA: can delete validation but not add new one

    - by user1882965
    My code is as follows If Cells(Target.Row, 2) = "" And (Cells(Target.Row, 3) = "" Or Cells(Target.Row, 3) = "") Then Sheets("MySheet").Activate Cells(Target.Row, 3).Activate ActiveCell.Validation.Delete If (Cells(Target.Row, 2) = "Type A") Then ActiveCell.Validation.Add Type:=xlValidateList, AlertStyle:=xlValidAlertStop, Operator:=xlBetween, Formula1:="=AvailableVersions" ElseIf (Cells(Target.Row, 2) = "Type B") Then ActiveCell.Validation.Delete Else ActiveCell.Validation.Add Type:=xlValidateWholeNumber, AlertStyle:=xlValidAlertInformation, Formula1:="0", Formula2:="9999999" End If End If So the issue I am having comes whenever I reach ActiveCell.Validation.Add Run Time Error '1004': Application-defined or object-defined error Not a very helpful error, and also this occurs with both number and list validation type, so I am sure it is not an issue with the list itself which has workbook level scope anyway. It never occurs on ActiveCell.Validation.Delete which I find weird? I have been all over google trying to find a solution, and most suggest that it is caused by running dynamic validation code from a button which hogs focus despite the Activate call, but I am running on sheet change event rather than on button press so I don't think this is my issue - any ideas? I've wasted basically a whole day on this! :(

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  • Scalable Database Tagging Schema

    - by Longpoke
    EDIT: To people building tagging systems. Don't read this. It is not what you are looking for. I asked this when I wasn't aware that RDBMS all have their own optimization methods, just use a simple many to many scheme. I have a posting system that has millions of posts. Each post can have an infinite number of tags associated with it. Users can create tags which have notes, date created, owner, etc. A tag is almost like a post itself, because people can post notes about the tag. Each tag association has an owner and date, so we can see who added the tag and when. My question is how can I implement this? It has to be fast searching posts by tag, or tags by post. Also, users can add tags to posts by typing the name into a field, kind of like the google search bar, it has to fill in the rest of the tag name for you. I have 3 solutions at the moment, but not sure which is the best, or if there is a better way. Note that I'm not showing the layout of notes since it will be trivial once I get a proper solution for tags. Method 1. Linked list tagId in post points to a linked list in tag_assoc, the application must traverse the list until flink=0 post: id, content, ownerId, date, tagId, notesId tag_assoc: id, tagId, ownerId, flink tag: id, name, notesId Method 2. Denormalization tags is simply a VARCHAR or TEXT field containing a tab delimited array of tagId:ownerId. It cannot be a fixed size. post: id, content, ownerId, date, tags, notesId tag: id, name, notesId Method 3. Toxi (from: http://www.pui.ch/phred/archives/2005/04/tags-database-schemas.html, also same thing here: http://stackoverflow.com/questions/20856/how-do-you-recommend-implementing-tags-or-tagging) post: id, content, ownerId, date, notesId tag_assoc: ownerId, tagId, postId tag: id, name, notesId Method 3 raises the question, how fast will it be to iterate through every single row in tag_assoc? Methods 1 and 2 should be fast for returning tags by post, but for posts by tag, another lookup table must be made. The last thing I have to worry about is optimizing searching tags by name, I have not worked that out yet. I made an ASCII diagram here: http://pastebin.com/f1c4e0e53

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  • calling a function from another function in python

    - by user1040503
    I have written this function that takes to strings in order to see if they are anagrams: def anagram_check(str_x, str_y): x = string1.replace(" ","") y = string2.replace(" ","") lower1 = x.lower() lower2 = y.lower() sorted1 = sorted(lower1) sorted2 = sorted(lower2) if sorted1 == sorted2: return True else: return False this function works fine, the problem is that now I need to use this function in another function in order to find anagrams in a text file. I want to print a list of tuples with all the anagrams in it. this is what i have done so far def anagrams_finder(words_num): anagrams = [] f = open("words.txt") a = list(f) list1 = ([s.replace('\n', '') for s in a]) list2 = ([i.lower() for i in list1]) list3 = list2[0:words_num] #number of words from text that need to be checked. for i in list3: .... I tried using for loops, while loops, appand.... but nothing seems to work. how can I use the first function in order to help me with the second? Please help...

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  • Mootools 1.2.4 delegation not working in IE8...?

    - by michael
    Hey there everybody-- So I have a listbox next to a form. When the user clicks an option in the select box, I make a request for the related data, returned in a JSON object, which gets put into the form elements. When the form is saved, the request goes thru and the listbox is rebuilt with the updated data. Since it's being rebuilt I'm trying to use delegation on the listbox's parent div for the onchange code. The trouble I'm having is with IE8 (big shock) not firing the delegated event. I have the following HTML: <div id="listwrapper" class="span-10 append-1 last"> <select id="list" name="list" size="20"> <option value="86">Adrian Franklin</option> <option value="16">Adrian McCorvey</option> <option value="196">Virginia Thomas</option> </select> </div> and the following script to go with it: window.addEvent('domready', function() { var jsonreq = new Request.JSON(); $('listwrapper').addEvent('change:relay(select)', function(e) { alert('this doesn't fire in IE8'); e.stop(); var status= $('statuswrapper').empty().addClass('ajax-loading'); jsonreq.options.url = 'de_getformdata.php'; jsonreq.options.method = 'post'; jsonreq.options.data = {'getlist':'<?php echo $getlist ?>','pkey':$('list').value}; jsonreq.onSuccess = function(rObj, rTxt) { status.removeClass('ajax-loading'); for (key in rObj) { status.set('html','You are currently editing '+rObj['cname']); if ($chk($(key))) $(key).value = rObj[key]; } $('lalsoaccomp-yes').set('checked',(($('naccompkey').value > 0)?'true':'false')); $('lalsoaccomp-no').set('checked',(($('naccompkey').value > 0)?'false':'true')); } jsonreq.send(); }); }); (I took out a bit of unrelated stuff). So this all works as expected in firefox, but IE8 refuses to fire the delegated change event on the select element. If I attach the change function directly to the select, then it works just fine. Am I missing something? Does IE8 just not like the :relay? Sidenote: I'm very new to mootools and javascripting, etc, so if there's something that can be improved code-wise, please let me know too.. Thanks!

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  • construct graph from python set type.

    - by Vincent
    The sort question, is the an off the self function to make a graph from a set of python sets? The longer: I have several python set types. They each overlap or some are sub sets of others. I would like to make a graph (as in nodes and edges) with the edges weighted by common intersection of the sets. There are several graphing packages for python. (NetworkX, igraph,...) I am not familiar with the use of any of them. Will any of them make a graph directly from a list of sets ie, MakeGraphfromSets(alistofsets) If not do you know of an example of how to take the list of sets to define the edges. It actually looks like it might be straight forward but an example is always good to have.

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  • IE6 background appears-disappears on scrolling

    - by itarato
    Hi, Given IE6, an UL-LI list and a background image for the UL container. <style> ul {background-image: url(images/bgr.png);} </style> ... <ul> <li>...</li> ... </ul> When I load the page, the background is randomly loaded, some parts are visible, some are not. Moreover, it changes on runtime when I'm scrolling on the page. When I scroll out the UL list and scroll back, different parts of the background will be visible, depends on the speed of scrolling. Do you have any idea? Thanks in advance.

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  • Can the Subversion client (svn) derefence symbolic links as if they were files?

    - by Ryan B. Lynch
    I have a directory on a Linux system that mostly contains symlinks to files on a different filesystem. I'd like to add the directory to a Subversion repository, dereferencing the symlinks in the process (treating them as the files they point to, rather than links). Generally, I'd like to be able to handle any working-copy operations with this behavior, but the 'svn add' command is where it starts, I think. The SVN client utility doesn't appear to have any options related to symlink dereferencing in the working copy. I didn't find any references to this in the manual (http://svnbook.red-bean.com/en/1.5/index.html), either. I found a poster on the SVN users mailing list who asked the same question but never received an answer, here: http://markmail.org/message/ngchfnzlmm43yj7h (That poster ended up using hard links instead of symlinks. That technique is not an option, in my case, because the real underlying files reside on a separate filesystem.) I'm using Subversion v1.6.1 on Fedora 11. For what it's worth, I know that there are alternative tools/techniques that could help approximate this behavior, but which I have to discard for various reasons. I've already considered [and dust-binned] these possibilities: - a "union" mount, merging all of the the directories containing the real files, with the SVN working-copy directory as the "top" layer in the union; - copying/moving the real files to the same filesystem as the SVN working-copy, and using hardlinks instead of symlinks; - non-SVN version control systems. These were all neat ideas, and I'm sure they are good solutions to other problems, but they won't work given the constraints of this environment and situation.

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  • SQLite Transaction fills a table BEFORE the transaction is commited

    - by user1500403
    Halo I have a code that creates a datatable (in memory) from a select SQL statement. However I realised that this datatable is filling during the procedure rather as a result of the transaction comit statment, it does the job but its slow. WHat amI doing wrong ? Inalready.Clear() 'clears a dictionary Using connection As New SQLite.SQLiteConnection(conectionString) connection.Open() Dim sqliteTran As SQLite.SQLiteTransaction = connection.BeginTransaction() Try oMainQueryR = "SELECT * FROM detailstable Where name= :name AND Breed= :Breed" Dim cmdSQLite As SQLite.SQLiteCommand = connection.CreateCommand() Dim oAdapter As New SQLite.SQLiteDataAdapter(cmdSQLite) With cmdSQLite .CommandType = CommandType.Text .CommandText = oMainQueryR .Parameters.Add(":name", SqlDbType.VarChar) .Parameters.Add(":Breed", SqlDbType.VarChar) End With Dim c As Long = 0 For Each row As DataRow In list.Rows 'this is the list with 500 names If Inalready.ContainsKey(row.Item("name")) Then Else c = c + 1 Form1.TextBox1.Text = " Fill .... " & c Application.DoEvents() Inalready.Add(row.Item("name"), row.Item("Breed")) cmdSQLite.Parameters(":name").Value = row.Item("name") cmdSQLite.Parameters(":Breed").Value = row.Item("Breed") oAdapter.Fill(newdetailstable) End If Next oAdapter.FillSchema(newdetailstable, SchemaType.Source) Dim z = newdetailstable.Rows.Count 'At this point the newdetailstable is already filled up and I havent even comited the transaction ' sqliteTran.Commit() Catch ex As Exception End Try End Using

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  • Python 2.6, 3 abstract base class misunderstanding

    - by Aaron
    I'm not seeing what I expect when I use ABCMeta and abstractmethod. This works fine in python3: from abc import ABCMeta, abstractmethod class Super(metaclass=ABCMeta): @abstractmethod def method(self): pass a = Super() TypeError: Can't instantiate abstract class Super ... And in 2.6: class Super(): __metaclass__ = ABCMeta @abstractmethod def method(self): pass a = Super() TypeError: Can't instantiate abstract class Super ... They both also work fine (I get the expected exception) if I derive Super from object, in addition to ABCMeta. They both "fail" (no exception raised) if I derive Super from list. I want an abstract base class to be a list but abstract, and concrete in sub classes. Am I doing it wrong, or should I not want this in python?

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  • Is this implementation truely tail-recursive?

    - by CFP
    Hello everyone! I've come up with the following code to compute in a tail-recursive way the result of an expression such as 3 4 * 1 + cos 8 * (aka 8*cos(1+(3*4))) The code is in OCaml. I'm using a list refto emulate a stack. type token = Num of float | Fun of (float->float) | Op of (float->float->float);; let pop l = let top = (List.hd !l) in l := List.tl (!l); top;; let push x l = l := (x::!l);; let empty l = (l = []);; let pile = ref [];; let eval data = let stack = ref data in let rec _eval cont = match (pop stack) with | Num(n) -> cont n; | Fun(f) -> _eval (fun x -> cont (f x)); | Op(op) -> _eval (fun x -> cont (op x (_eval (fun y->y)))); in _eval (fun x->x) ;; eval [Fun(fun x -> x**2.); Op(fun x y -> x+.y); Num(1.); Num(3.)];; I've used continuations to ensure tail-recursion, but since my stack implements some sort of a tree, and therefore provides quite a bad interface to what should be handled as a disjoint union type, the call to my function to evaluate the left branch with an identity continuation somehow irks a little. Yet it's working perfectly, but I have the feeling than in calling the _eval (fun y->y) bit, there must be something wrong happening, since it doesn't seem that this call can replace the previous one in the stack structure... Am I misunderstanding something here? I mean, I understand that with only the first call to _eval there wouldn't be any problem optimizing the calls, but here it seems to me that evaluation the _eval (fun y->y) will require to be stacked up, and therefore will fill the stack, possibly leading to an overflow... Thanks!

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  • How to let an average user design a boolean expression graphically

    - by Svein Bringsli
    In our application there's a list of customers, and a list of keywords (among other things). Each customer can have a number of keywords, but it's not mandatory. So for instance, one customer can have the keywords "retail" and "chain", one can have only "contractor" and a third can have none at all. I want to let the user make a selection of customers based on these keywords, but not having to write (retail AND chain) or contractor and not wholesale I would like to make it as user-friendly as possible, and ideally with only "simple" controls, like checkboxes, comboboxes etc. Does anyone have any suggestions on how to design this? Or maybe some examples of applications where there are similar functionality?

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  • What C# data types can be nullable types?

    - by Randy Minder
    Can someone give me a list, or point me to where I can find a list of C# data types that can be a nullable type? For example: I know that Nullable<int> is ok I know that Nullable<byte[]> is not. I'd like to know which types are nullable and which are not. BTW, I know I can test for this at runtime. However, this is for a code generator we're writing, so I don't have an actual type. I just know that a column is "string" or "int32" etc. Thanks.

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  • Datetime comparaison in CAML Query for Sharepoint

    - by Garcia Julien
    Hi, i'm trying to have some item from a sharepoint list, depends on date in a custom column. I've created my query with 2U2 Caml Builder, and that's worked but when I put it in my own code in my webpart, it always return to me all the items od the list. Here is my code: DateTime startDate = new DateTime(Int32.Parse(year), 1, 1); DateTime endDate = new DateTime(Int32.Parse(year), 12, 31); SPQuery q = new SPQuery(); q.Query = "<Query><Where><And><Geq><FieldRef Name='Publicate Date' /><Value IncludeTimeValue='FALSE' Type='DateTime'>" + SPUtility.CreateISO8601DateTimeFromSystemDateTime(startDate) + "</Value></Geq><Leq><FieldRef Name='Publicate_x0020_Date' /><Value IncludeTimeValue='FALSE' Type='DateTime'>" + SPUtility.CreateISO8601DateTimeFromSystemDateTime(endDate) + "</Value></Leq></And></Where></Query>"; SPListItemCollection allItem = library.GetItems(q);

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  • Google App Engine PersistenceManager can process multiple objects ?

    - by Frank
    I have some code like this : PersistenceManager pm=PMF.get().getPersistenceManager(); String query="select from "+PayPal_Message.class.getName()+" where processed == false order by time desc"; List<PayPal_Message> messages=(List<PayPal_Message>)pm.newQuery(query).execute(); if (messages.isEmpty()) { } else { for (PayPal_Message g : messages) { Contact_Info_Entry A_Contact_Entry=Process_PayPal_Message_To_Get_A_License(g.getContent().getValue()); pm=PMF.get().getPersistenceManager(); try { pm.makePersistent(A_Contact_Entry); g.setProcessed(true); pm.makePersistent(g); } catch (Exception e) { Send_Email(Email_From,"[email protected]","Servlet Error Message [ "+time+" ]",new Text(e.toString())); } // finally { pm.close(); } } } pm.close(); I wonder if it's ok to use the pm above to process multiple objects before closing it. Or do I have to get and close pm for processing each object ?

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