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• How to prevent multiple registrations?

  - by GG.

  I develop a political survey website where anyone can vote once. Obviously I have to prevent multiple registrations for the survey remains relevant. Already I force every user to login with their Google, Facebook or Twitter account. But they can authenticate 3 times if they have an account on each, or authenticate with multiple accounts of the same platform (I have 3 accounts on Google). So I thought also store the IP address, but they can still go through a proxy... I thought also keep the HTTP User Agent with PHP's get_browser(), although they can still change browsers. I can extract the OS with a regex, to change OS is less easier than browsers. And there is also geolocation, for example with the Google Map API. So to summarize, several ideas: 1 / SSO Authentication (I keep the email) 2 / IP Address 3 / HTTP User Agent 4 / Geolocation with an API Have you any other ideas that I did not think? How to embed these tests? Execute in what order? Have you already deploy this kind of solution?

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• Examples of monoids/semigroups in programming

  - by jkff

  It is well-known that monoids are stunningly ubiquitous in programing. They are so ubiquitous and so useful that I, as a 'hobby project', am working on a system that is completely based on their properties (distributed data aggregation). To make the system useful I need useful monoids :) I already know of these: Numeric or matrix sum Numeric or matrix product Minimum or maximum under a total order with a top or bottom element (more generally, join or meet in a bounded lattice, or even more generally, product or coproduct in a category) Set union Map union where conflicting values are joined using a monoid Intersection of subsets of a finite set (or just set intersection if we speak about semigroups) Intersection of maps with a bounded key domain (same here) Merge of sorted sequences, perhaps with joining key-equal values in a different monoid/semigroup Bounded merge of sorted lists (same as above, but we take the top N of the result) Cartesian product of two monoids or semigroups List concatenation Endomorphism composition. Now, let us define a quasi-property of an operation as a property that holds up to an equivalence relation. For example, list concatenation is quasi-commutative if we consider lists of equal length or with identical contents up to permutation to be equivalent. Here are some quasi-monoids and quasi-commutative monoids and semigroups: Any (a+b = a or b, if we consider all elements of the carrier set to be equivalent) Any satisfying predicate (a+b = the one of a and b that is non-null and satisfies some predicate P, if none does then null; if we consider all elements satisfying P equivalent) Bounded mixture of random samples (xs+ys = a random sample of size N from the concatenation of xs and ys; if we consider any two samples with the same distribution as the whole dataset to be equivalent) Bounded mixture of weighted random samples Which others do exist?

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• Custom QAbstractGraphicsShapeItem very slow in Qt Jambi

  - by Mene

  I try to implement an own QAbstractGraphicsShapeItem in Qt Jambi (4.5) but as soon as I implement a custom class (rather than use e.g. QGraphicsEllipseItem) the rendering speed drops by about on order of magnitude. If looked in the original Code of QGraphicsEllipseItem and it seems to do basicly the same. class Circle extends QAbstractGraphicsShapeItem { final private QRectF rect = new QRectF(); public final void setRect(double x, double y, double w, double h) { QRectF newRect = new QRectF(x, y, w, h); if (!newRect.equals(rect)) { prepareGeometryChange(); this.rect.setX(x); this.rect.setY(y); this.rect.setWidth(w); this.rect.setHeight(h); this.update(rect); } } @Override public final QRectF boundingRect() { return rect; } QPainterPath shape; @Override public final QPainterPath shape() { if (shape == null) { QPainterPath path = new QPainterPath(); path.addEllipse(rect); QPainterPathStroker stroker = new QPainterPathStroker(); QPen pen = this.pen(); stroker.setCapStyle(pen.capStyle()); stroker.setWidth(pen.widthF()); shape = stroker.createStroke(path); } return shape; } @Override public final void paint(QPainter painter, QStyleOptionGraphicsItem option, QWidget widget) { painter.setPen(this.pen()); painter.setBrush(this.brush()); painter.drawEllipse(this.rect); } } I need to render a lot of objects and they are mostly moving, so speed is essential. Anyone knows how to speed this up? I underestand that Java might be slower then the nativ code in the library. But the code in the paint method seems not to be the problem, since commenting it out doesn't change the speed notably.

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• How do I tell gcc to relax its restrictions on typecasting when calling a C function from C++?

  - by Daryl Spitzer

  I'm trying to use Cmockery to mock C functions called from C++ code. Because the SUT is in C++, my tests need to be in C++. When I use the Cmockery expect_string() macro like this: expect_string(mock_function, url, "Foo"); I get: my_tests.cpp: In function ‘void test_some_stuff(void**)’: my_tests.cpp:72: error: invalid conversion from ‘void*’ to ‘const char*’ my_tests.cpp:72: error: initializing argument 5 of ‘void _expect_string(const char*, const char*, const char*, int, const char*, int)’ I see in cmockery.h that expect_string is defined: #define expect_string(function, parameter, string) \ expect_string_count(function, parameter, string, 1) #define expect_string_count(function, parameter, string, count) \ _expect_string(#function, #parameter, __FILE__, __LINE__, (void*)string, \ count) And here's the prototype for _expect_string (from cmockery.h): void _expect_string( const char* const function, const char* const parameter, const char* const file, const int line, const char* string, const int count); I believe the problem is that I'm compiling C code as C++, so the C++ compiler is objecting to (void*)string in the expect_string_count macro being passed as the const char* string parameter to the _expect_string() function. I've already used extern "C" around the cmockery.h include in my_tests.cpp like this: extern "C" { #include <cmockery.h> } ...in order to get around name-mangling problems. (See "How do I compile and link C++ code with compiled C code?") Is there a command-line option or some other means of telling g++ how to relax its restrictions on typecasting from my test's C++ code to the C function in cmockery.c? This is the command I'm currently using to build my_tests.cpp: g++ -m32 -I ../cmockery-0.1.2 -c my_tests.cpp -o $(obj_dir)/my_tests.o

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• MySQL GIS and Spatial Extensions - how to map regions and query against them

  - by chibineku

  I am trying to make a smartphone app which will return a list of users within a certain proximity, say 100m. It's easy to get the coordinates of my BlackBerry and write them to a database, but in order to return a list of other users within 100m, I need to pull every other record from the database and compare the distance between the two points, checking to see if it's within range, before outputting that user's information. This is going to be time consuming if there are many users involved. So I would like to map areas (countries, cities, I'm not yet sure of the resolution I'll need) so that I can first target a smaller subset of all users. This will save on processing time. I have read the basics of GIS and spatial querying on the mysql website but to be honest the query is over my head and I hate copying and pasting code without understanding it. Plus it only checks for proximity - I want to first check if a coordinate falls within a certain area. Does anyone have any experience of such matters and feel like giving me some pointers? Resources such as any preexisting databases of points describing countries as polygons would be really helpful too. Many thanks to anyone who takes the time :)

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• Set the selected item for a combobox in a datagrid

  - by JingJingTao

  I am using a datagrid which has many combobox fields in it, when I click the datagrid combobox the selected item or highlighted value is the last item in the list, but I would like it to highlight the first(top) item in the list. I know for just a combobox, all I need to do is change the combobox.selecteditem or combobox.selectedindex, but I'm not sure what to do in this case. I have binded the combobox to a table in the database and used a datatable to store the combobox values and then I add a row to the datatable, I think the reason the last item in the combobox is highlighted is because I added a row to the datatable. Thank you for your help. String strGetTypes = "SELECT holidaycodeVARCHAR4Pk, codedescVARCHAR45 FROM holidaytype ORDER BY holidaycodeVARCHAR4Pk Desc"; DataTable dtHolidayType = new DataTable(); MySqlDataAdapter dbaElements = new MySqlDataAdapter(strGetTypes, ShareSqlSettings.dbConnect); dbaElements.Fill(dtHolidayType); DataGridViewComboBoxCell cboxDays = new DataGridViewComboBoxCell(); cboxDays.DataSource = dtHolidayType; cboxDays.DisplayMember = "codedescVARCHAR45"; cboxDays.ValueMember = "holidaycodeVARCHAR4Pk"; //Blank row dtHolidayType.Rows.Add(1); // gridDailyEmp.Rows[j].Cells[day] = cboxDays;

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• Conversion failed: SqlParameter and DateTime

  - by Tim

  I'm changing old,vulnerable sqlcommands with SqlParameters but get a SqlException: System.Data.SqlClient.SqlException {"Conversion failed when converting datetime from character string."} on sqlCommand.ExecuteScalar() Dim sqlString As String = _ "SELECT TOP 1 " & _ "fiSL " & _ "FROM " & _ "tabData AS D " & _ "WHERE " & _ "D.SSN_Number = '@SSN_Number' " & _ "AND D.fiProductType = 1 " & _ "AND D.Repair_Completion_Date > '@Repair_Completion_Date' " & _ "ORDER BY " & _ "D.Repair_Completion_Date ASC" Dim obj As Object Dim sqlCommand As SqlCommand Try sqlCommand = New SqlCommand(sqlString, Common.MyDB.SqlConn_RM2) sqlCommand.CommandTimeout = 120 sqlCommand.Parameters.AddWithValue("@SSN_Number", myClaim.SSNNumber) sqlCommand.Parameters.AddWithValue("@Repair_Completion_Date", myClaim.RepairCompletionDate) If Common.MyDB.SqlConn_RM2.State <> System.Data.ConnectionState.Open Then Common.MyDB.SqlConn_RM2.Open() obj = sqlCommand.ExecuteScalar() Catch ex As Exception Dim debug As String = ex.ToString Finally Common.MyDB.SqlConn_RM2.Close() End Try myClaim.RepairCompletionDate is a SQLDateTime. Do i have to remove the quotes in the sqlString to compare Date columns? But then i dont get a exception but incorrect results.

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• How to prevent parallel builds per build configuration across multiple Build Agents

  - by vanslly

  I have many build configurations in TeamCity, each servicing a large project. In the past if a build is kicked off the Build Agent could be busy for up to 20min! In order to improve throughput I installed a second Build Agent on the same machine such that if a build run is kicked off by say Build Agent 1 and it is busy for 20min and someone from another project makes a change then Build Agent 2 can do the build for the other project without needing to wait on the current build run to finish. All was well until two successive check-ins resulted in both Build Agents running a build for a single build configuration in parallel. Since some resources are shared, IIS directories & databases, I don't want a single build configuration to run on both Build Agents in parallel. How can I ensure a build isn't triggered if a build is currently running for that build configuration on a different build agent? One way seems to involve environmental variables and ensuring a 50/50 split by Build Agent in terms of build configuration compatibility, but that seems a little clunky.

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• Using sqldatareader in asp.net

  - by Phil

  I have this code to get data; s = "select documents.filename, documents.description, documents.filesize from documents, contentdocuments, content where contentdocuments.contentid = content.id and content.id = @contentid and contentdocuments.documentsid = documents.id ORDER BY documents.description" x = New SqlCommand(s, c) x.Parameters.Add("@contentid", SqlDbType.Int) x.Parameters("@contentid").Value = contentid c.Open() r = x.ExecuteReader If r.Read Then DownloadsRepeater.DataSource = r DownloadsRepeater.DataBind() **imagepath = "<img src='images/'" & getimage(r("filename")) & " border='0'** align='absmiddle'" End If c.Close() r.Close() The problem is on the line; imagepath = "<img src='images/'" & getimage(r("filename")) & " The error is; Invalid attempt to read when no data is present. How can I check to make sure data is present and get rid of this error? I thought the 'if r.read' did this? Thanks :EDIT: Function getimage(ByVal strin As String) As String If strin > "" Then dotpos = InStrRev(strin, ".") ext = Right(strin, Len(strin) - dotpos) getimage = ext & ".gif" End If Return getimage End Function

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• Mysql Server Optimization

  - by Ish Kumar

  Hi Geeks, We are having serious MySQL(InnoDB) performance issues at a moment when we do: (10-20) insertions on TABLE1 (10-20) updates on TABLE2 Note: Both above operations happens within fraction of a second. And this occurs every few (10-15) minutes. And all online users (approx 400-600) doing read operation on join of TABLE1 & TABLE2 every 1 second. Here is our mysql configuration info: http://docs.google.com/View?id=dfrswh7c_117fmgcmb44 Issues: Lot queries wait and expire later (saw it from phpmyadmin / processes). My poor MySQL server crashes sometimes Questions Q1: Any suggestions to optimize at MySQL level? Q2: I thinking to use persistent connections at application level, is it right? Info Added Later: Database Engine: InnoDB TABLE1 : 400,000 rows (inserting 8,000 daily) & TABLE2: 8,000 rows 1 second query: SELECT b.id, b.user_id, b.description, b.debit, b.created, b.price, u.username, u.email, u.mobile FROM TABLE1 b, TABLE2 u WHERE b.credit = 0 AND b.user_id = u.id AND b.auction_id = "12345" ORDER BY b.id DESC LIMIT 10; // there are few more but they are not so critical. Indexing is good, we are using them wisely. In above query all id's are indexed And TABLE1 has frequent insertions and TABLE2 has frequent updates.

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• return sql query in xml format in python

  - by Ramy

  When I first started working at the company that i work at now, I created a java application that would run batches of jasper-reports. In order to determine which parameters to use for each report in the set of reports, I run a sql query (on sqlserver). I wrote the application to take an xml file with a set of parameters for each report to be generated in the set. so, my process has become, effectively, three steps: run the sql query and return the results in XML format (using 'for XML auto') run the results of the sql query through an XSLT transformation so the xml is formatted in such a way that is friendly with the java application i wrote. run the java application with that final xml file As you can imagine, what I'd like to do is accomplish these steps in python, but i'm not quite sure how to get started. I know how to run an SQL query in Python. I see plenty of documentation about how to write your own xml document with Python. I even see documentation for xsl transformations in python. the big question is how to get the results of the sql query in XML through python. Any and all pointers would be very valuable. Thanks, _Ramy

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• How to TDD Asynchronous Events?

  - by Padu Merloti

  The fundamental question is how do I create a unit test that needs to call a method, wait for an event to happen on the tested class and then call another method (the one that we actually want to test)? Here's the scenario if you have time to read further: I'm developing an application that has to control a piece of hardware. In order to avoid dependency from hardware availability, when I create my object I specify that we are running in test mode. When that happens, the class that is being tested creates the appropriate driver hierarchy (in this case a thin mock layer of hardware drivers). Imagine that the class in question is an Elevator and I want to test the method that gives me the floor number that the elevator is. Here is how my fictitious test looks like right now: [TestMethod] public void TestGetCurrentFloor() { var elevator = new Elevator(Elevator.Environment.Offline); elevator.ElevatorArrivedOnFloor += TestElevatorArrived; elevator.GoToFloor(5); //Here's where I'm getting lost... I could block //until TestElevatorArrived gives me a signal, but //I'm not sure it's the best way int floor = elevator.GetCurrentFloor(); Assert.AreEqual(floor, 5); } Edit: Thanks for all the answers. This is how I ended up implementing it: [TestMethod] public void TestGetCurrentFloor() { var elevator = new Elevator(Elevator.Environment.Offline); elevator.ElevatorArrivedOnFloor += (s, e) => { Monitor.Pulse(this); }; lock (this) { elevator.GoToFloor(5); if (!Monitor.Wait(this, Timeout)) Assert.Fail("Elevator did not reach destination in time"); int floor = elevator.GetCurrentFloor(); Assert.AreEqual(floor, 5); } }

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• R:how to get grep to return the match, rather than the whole string

  - by Mike Dewar

  Hi, I have what is probably a really dumb grep in R question. Apologies, because this seems like it should be so easy - I'm obviously just missing something. I have a vector of strings, let's call it alice. Some of alice is printed out below: T.8EFF.SP.OT1.D5.VSVOVA#4 T.8EFF.SP.OT1.D6.LISOVA#1 T.8EFF.SP.OT1.D6.LISOVA#2 T.8EFF.SP.OT1.D6.LISOVA#3 T.8EFF.SP.OT1.D6.VSVOVA#4 T.8EFF.SP.OT1.D8.VSVOVA#3 T.8EFF.SP.OT1.D8.VSVOVA#4 T.8MEM.SP#1 T.8MEM.SP#3 T.8MEM.SP.OT1.D106.VSVOVA#2 T.8MEM.SP.OT1.D45.LISOVA#1 T.8MEM.SP.OT1.D45.LISOVA#3 I'd like grep to give me the number after the D that appears in some of these strings, conditional on the string containing "LIS" and an empty string or something otherwise. I was hoping that grep would return me the value of a capturing group rather than the whole string. Here's my R-flavoured regexp: pattern <- (?<=\\.D)([0-9]+)(?=.LIS) nothing too complicated. But in order to get what I'm after, rather than just using grep(pattern, alice, value = TRUE, perl = TRUE) I'm doing the following, which seems bad: reg.out <- regexpr( "(?<=\\.D)[0-9]+(?=.LIS)", alice, perl=TRUE ) substr(alice,reg.out,reg.out + attr(reg.out,"match.length")-1) Looking at it now it doesn't seem too ugly, but the amount of messing about it's taken to get this utterly trivial thing working has been embarrassing. Anyone any pointers about how to go about this properly? Bonus marks for pointing me to a webpage that explains the difference between whatever I access with $,@ and attr.

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• Password Cracking in 2010 and Beyond

  - by mttr

  I have looked a bit into cryptography and related matters during the last couple of days and am pretty confused by now. I have a question about password strength and am hoping that someone can clear up my confusion by sharing how they think through the following questions. I am becoming obsessed about these things, but need to spend my time otherwise :-) Let's assume we have an eight-digit password that consists of upper and lower-case alphabetic characters, numbers and common symbols. This means we have 8^96 ~= 7.2 quadrillion different possible passwords. As I understand there are at least two approaches to breaking this password. One is to try a brute-force attack where we try to guess each possible combination of characters. How many passwords can modern processors (in 2010, Core i7 Extreme for eg) guess per second (how many instructions does a single password guess take and why)? My guess would be that it takes a modern processor in the order of years to break such a password. Another approach would consist of obtaining a hash of my password as stored by operating systems and then search for collisions. Depending on the type of hash used, we might get the password a lot quicker than by the bruteforce attack. A number of questions about this: Is the assertion in the above sentence correct? How do I think about the time it takes to find collisions for MD4, MD5, etc. hashes? Where does my Snow Leopard store my password hash and what hashing algorithm does it use? And finally, regardless of the strength of file encryption using AES-128/256, the weak link is still my en/decryption password used. Even if breaking the ciphered text would take longer than the lifetime of the universe, a brute-force attack on my de/encryption password (guess password, then try to decrypt file, try next password...), might succeed a lot earlier than the end of the universe. Is that correct? I would be very grateful, if people could have mercy on me and help me think through these probably simple questions, so that I can get back to work.

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• How to create refresh statements for TableAdapter objects in Visual Studio?

  - by Mark Wilkins

  I am working on developing an ADO.NET data provider and an associated DDEX provider. I am unable to convince the Visual Studio TableAdapater Configuration Wizard to generate SQL statements to refresh the data table after inserts and updates. It generates the insert and delete statements but will not produce the select statements to do the refresh. The functionality referred to can be accessed by dropping a table from the Server Explorer (inside Visual Studio) onto a DataSet (e.g., DataSet1.xsd). It creates a TableAdapter object and configures SELECT, UPDATE, DELETE, and INSERT statements. If you right click on the TableAdapter object, the context menu has a “Configure” option that starts the “TableAdapter Configuration Wizard”. The first dialog of that wizard has an Advanced Options button, which leads to an option titled “Refresh the data table”. When used with SQL Server tables, that option causes a statement of the form “select field1, field2, …” to be added on to the end of the commands for the TableAdapter’s InsertCommand and UpdateCommand. Do you have any idea what type property or interface might need to be exposed from the DDEX provider (or maybe the ADO.NET data provider) in order to make Visual Studio add those refresh statements to the update/insert commands? The MSDN documentation for the Advanced SQL Generation Options Dialog Box has a note stating, “Refreshing the data table is only supported on databases that support batching of SQL statements.” This seems to imply that a .NET data provider might need to expose some property indicating such behavior is supported. But I cannot find it. Any ideas?

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• Using bitwise operators on > 32 bit integers

  - by dqhendricks

  I am using bitwise operations in order to represent many access control flags within one integer. ADMIN_ACCESS = 1; EDIT_ACCOUNT_ACCESS = 2; EDIT_ORDER_ACCESS = 4; var myAccess = 3; // ie: ( ADMIN_ACCESS | EDIT_ACCOUNT_ACCESS ) if ( myAccess & EDIT_ACCOUNT_ACCESS ) { // check for correct access // allow for editing of account } Most of this is occurring on the PHP side of my project. There is one piece however where Javascript is used to join several access flags using | when saving someone's access level. This works fine to a point. I have found that once an integer (flag) gets too large ( 32bit), it no longer works correctly with bitwise operators in Javascript. For instance: alert( 4294967296 | 1 ); // equals 1, but should equal 4294967297 I am trying to find a workaround for this so that I do not have to limit my number of access control flags to 32. Each access control flag is two times the previous control flag so that each control flag will not interfere with other control flags. dec(4) = bin(100) dec(8) = bin(1000) dec(16) = bin(10000) I have noticed that when adding two of these flags together with a simple +, it seems to come out with the same answer as a bitwise or operation, but am having trouble wrapping my head around whether this is a simple substitution, or if there might be problems with doing this. Can anyone comment on the validity of this workaround? Example: (4294967296 | 262144 | 524288) == (4294967296 + 262144 + 524288)

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• Is It Incorrect to Make Domain Objects Aware of The Data Access Layer?

  - by Noah Goodrich

  I am currently working on rewriting an application to use Data Mappers that completely abstract the database from the Domain layer. However, I am now wondering which is the better approach to handling relationships between Domain objects: Call the necessary find() method from the related data mapper directly within the domain object Write the relationship logic into the native data mapper (which is what the examples tend to do in PoEAA) and then call the native data mapper function within the domain object. Either it seems to me that in order to preserve the 'Fat Model, Skinny Controller' mantra, the domain objects have to be aware of the data mappers (whether it be their own or that they have access to the other mappers in the system). Additionally it seems that Option 2 unnecessarily complicates the data access layer as it creates table access logic across multiple data mappers instead of confining it to a single data mapper. So, is it incorrect to make the domain objects aware of the related data mappers and to call data mapper functions directly from the domain objects? Update: These are the only two solutions that I can envision to handle the issue of relations between domain objects. Any example showing a better method would be welcome.

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• Do the new NoPIA and Type Equivalence features in C#/.NET 4.0 mean Microsoft.mshtml.dll is no longer

  - by jpierson

  I'm maintaining a WPF based application which contains a WinForms based WebBrowser control that based on the IE web browser control. When we deploy, we have had to also supply Microsoft.mshtml.dll and do some custom configuration stuff for our ClickOnce publishing process as well in order to get things to work. I'm curious that with the new NoPIA and Type Equivalence features and dynamic type capabilities in C# 4.0 can we expect that if we upgrade that we can remove the dependencies on the Microsoft.mshtml.dll assembly? If so this will not only reduce the size of our deployment quite a bit but will also simplify our publishing process as well. It is my understanding that we should be able embed the types that normally get automatically generated into extra assemblies for COM types such as the MapPoint Control by Visual Studio. I don't know if this also applies to the Microsoft.mshtml.dll or even how it is done even in the most simple of cases. If somebody could provide an explanation about what the practical impact of these new features are on a project that relies on COM interop and especially the Microsoft.mshtml.dll assembly it would be of great help to me.

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• Random Pairings that don't Repeat

  - by Andrew Robinson

  This little project / problem came out of left field for me. Hoping someone can help me here. I have some rough ideas but I am sure (or at least I hope) a simple, fairly efficient solution exists. Thanks in advance.... pseudo code is fine. I generally work in .NET / C# if that sheds any light on your solution. Given: A pool of n individuals that will be meeting on a regular basis. I need to form pairs that have not previously meet. The pool of individuals will slowly change over time. For the purposes of pairing, (A & B) and (B & A) constitute the same pair. The history of previous pairings is maintained. For the purpose of the problem, assume an even number of individuals. For each meeting (collection of pairs) and individual will only pair up once. Is there an algorithm that will allow us to form these pairs? Ideally something better than just ordering the pairs in a random order, generating pairings and then checking against the history of previous pairings. In general, randomness within the pairing is ok.

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• How can I make this method more Scalalicious

  - by Neil Chambers

  I have a function that calculates the left and right node values for some collection of treeNodes given a simple node.id, node.parentId association. It's very simple and works well enough...but, well, I am wondering if there is a more idiomatic approach. Specifically is there a way to track the left/right values without using some externally tracked value but still keep the tasty recursion. /* * A tree node */ case class TreeNode(val id:String, val parentId: String){ var left: Int = 0 var right: Int = 0 } /* * a method to compute the left/right node values */ def walktree(node: TreeNode) = { /* * increment state for the inner function */ var c = 0 /* * A method to set the increment state */ def increment = { c+=1; c } // poo /* * the tasty inner method * treeNodes is a List[TreeNode] */ def walk(node: TreeNode): Unit = { node.left = increment /* * recurse on all direct descendants */ treeNodes filter( _.parentId == node.id) foreach (walk(_)) node.right = increment } walk(node) } walktree(someRootNode) Edit - The list of nodes is taken from a database. Pulling the nodes into a proper tree would take too much time. I am pulling a flat list into memory and all I have is an association via node id's as pertains to parents and children. Adding left/right node values allows me to get a snapshop of all children (and childrens children) with a single SQL query. The calculation needs to run very quickly in order to maintain data integrity should parent-child associations change (which they do very frequently). In addition to using the awesome Scala collections I've also boosted speed by using parallel processing for some pre/post filtering on the tree nodes. I wanted to find a more idiomatic way of tracking the left/right node values. After looking at the answers listed I have settled on this synthesised version: def walktree(node: TreeNode) = { def walk(node: TreeNode, counter: Int): Int = { node.left = counter node.right = treeNodes .filter( _.parentId == node.id) .foldLeft(counter+1) { (counter, curnode) => walk(curnode, counter) + 1 } node.right } walk(node,1) }

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• Moq, a translator and an expression

  - by jeriley

  I'm working with an expression within a moq-ed "Get Service" and ran into a rather annoying issue. In order to get this test to run correctly and the get service to return what it should, there's a translator in between that takes what you've asked for, sends it off and gets what you -really- want. So, thinking this was easy I attempt this ... the fakelist is the TEntity objects (translated, used by the UI) and TEnterpriseObject is the actual persistance. mockGet.Setup(mock => mock.Get(It.IsAny<Expression<Func<TEnterpriseObject, bool>>>())).Returns( (Expression<Func<TEnterpriseObject, bool>> expression) => { var items = new List<TEnterpriseObject>(); var translator = (IEntityTranslator<TEntity, TEnterpriseObject>) ObjectFactory.GetInstance(typeof (IEntityTranslator<TEntity, TEnterpriseObject>)); fakeList.ForEach(fake => items.Add(translator.ToEnterpriseObject(fake))); items = items.Where(expression); var result = new List<TEnterpriseObject>(items); fakeList.Clear(); result.ForEach(item => translator.ToEntity(item)); return items; }); I'm getting the red squigglie under there items.where(expression) -- says it can't be infered from usage (confused between <Func<TEnterpriseObject,bool>> and <Func<TEnterpriseObject,int,bool>>) A far simpler version works great ... mockGet.Setup(mock => mock.Get(It.IsAny<Expression<Func<TEntity, bool>>>())).Returns( (Expression<Func<TEntity, bool>> expression) => fakeList.AsQueryable().Where(expression)); so I'm not sure what I'm missing... ideas?

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• URL "fragment identifier" semantics for HTML documents

  - by Pointy

  I've been working with a new installation of the "MoinMoin" wiki software. As I was playing with it, typing in mostly random test pages, I created a link with a fragment blah blah see also [[SomeStuff#whatever|some other stuff about whatever]] Then I needed to figure out how to create the anchor for that "whatever" fragment identifier. I don't recall having to do that with MediaWiki, so I had to dig around, but finally I found that MoinMoin has an "Anchor" macro: == Whatever == <<Anchor(whatever)>> Looking at the generated HTML, I was surprised to see an empty <span> tag with an "id" value of "whatever". I expected that it'd be an <a> tag with a "name" attribute of "whatever". I dug around and found the source, and there's a comment that says they changed it from an <a> tag in order to avoid some IE problem with <pre> sections. This confused me — not because of the IE thing, but because it looked to me as if their "fix" had left the whole anchor mechanism completely broken. Much to my surprise, however, further testing indicated that it worked fine. I wrote a test page with 300 <span> tags all with "id" values, and I further shocked myself when Firefox behaved exactly as I would have expected it to had I used <a> tags. It also worked when I changed all the <span> tags to <em>. So by this time, you're either as surprised as I was, or else you're thinking "how can somebody that dumb have so many reputation points?" If you're in the second category, is it really the case that I've been typing in HTML for about 15 years now — a lot of HTML — and it's somehow escaped my notice that browsers use the HTML fragment to find any sort of element with a matching "id"? mind status: blown

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• VEMap and a GeoRSS feed(hosted separately)

  - by Alexis Abril

  The scenario is as follows: A WCF web service exists that outputs a valid GeoRSS feed. This lives in its own domain as a number of different applications have access to it. A web page(on a different site) has been created with an instance of a VEMap(Bing/Virtual Earth map object). Now, VEMap can accept an input feed in this format via the following: var layer = new VEShapeLayer(); var veLayerSpec = new VEShapeSourceSpecification(VEDataType.GeoRSS, "someurl", layer); map.ImportShapeLayerData(veLayerSpec, onComplete, true); onComplete is a callback function I'm using to replace the default pin graphic with something custom. The question is in regards to "someurl", which is a path to a local xml file containing the geographic information(georss simple format). I've realized this feed and the map must be hosted in the same domain, so I've created a generic handler that reads the remote feed and returns it in the same format. var veLayerSpec = new VEShapeSourceSpecification(VEDataType.GeoRSS, "/somelocalhandler.ashx", layer); When I do this, I get the VEMap error("z is null"). This is the same error one would receive when trying to access a remote feed. When I copy the feed into a local xml file(ie, "feed.xml") there is no error. The order of operations is currently: remote feed - local handler - VEMap import If I'm over complicating this procedure, let me know! I'm a bit new to the Bing Maps API and might have missed something. Any assistance is appreciated.

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• First run notepad with my.cfg and only then start the service

  - by Viv Coco

  Hi all, I install along with my application: 1) a service that starts and stops my application as needed 2) a conf file that contains actually the user data and that will be shown to the user to modify as needed (I give the user the chance to change it by running notepad.exe with my conf file during installing) The problem is that in my code the service I install starts before the user had the chance to modify the conf file. What I would like is: 1) first the user gets the chance to change the conf file (run notepad.exe with the conf file) 2) only afterward start the service <Component Id="MyService.exe" Guid="GUID"> <File Id="MyService.exe" Source="MyService.exe" Name="MyService.exe" KeyPath="yes" Checksum="yes" /> <ServiceInstall Id='ServiceInstall' DisplayName='MyService' Name='MyService' ErrorControl='normal' Start='auto' Type='ownProcess' Vital='yes'/> <ServiceControl Id='ServiceControl' Name='MyService' Start='install' Stop='both' Remove='uninstall'/> </Component> <Component Id="my.conf" Guid="" NeverOverwrite="yes"> <File Id="my.cfg" Source="my.cfg_template" Name="my.cfg" KeyPath="yes" /> </Component> [...] <Property Id="NOTEPAD">Notepad.exe</Property> <CustomAction Id="LaunchConfFile" Property="NOTEPAD" ExeCommand="[INSTALLDIR]my.cfg" Return="ignore" Impersonate="no" Execute="deferred"/> <!--Run only on installs--> <InstallExecuteSequence> <Custom Action='LaunchConfFile' Before='InstallFinalize'>(NOT Installed) AND (NOT UPGRADINGPRODUCTCODE)</Custom> </InstallExecuteSequence> What am I doing wrong in the above code and how could I change it in order to achieve what I need? (first run notepad with my conf file and then start the service). TIA, Viv

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• Rails ActiveRecord::MultiparameterAssignmentErrors

  - by Neil Middleton

  I have the following code in my model: attr_accessor :expiry_date validates_presence_of :expiry_date, :on => :create, :message => "can't be blank" and the following in my view: <%= date_select :account, :expiry_date, :discard_day => true, :start_year => Time.now.year, :end_year => Time.now.year + 15, :order => [:month, :year] %> However, when I submit my form I get: ActiveRecord::MultiparameterAssignmentErrors in SignupController#create /Users/x/.rvm/gems/ruby-1.8.6-p383/gems/activerecord-2.3.5/lib/active_record/base.rb:3073:in `execute_callstack_for_multiparameter_attributes' /Users/x/.rvm/gems/ruby-1.8.6-p383/gems/activerecord-2.3.5/lib/active_record/base.rb:3028:in `assign_multiparameter_attributes' /Users/x/.rvm/gems/ruby-1.8.6-p383/gems/activerecord-2.3.5/lib/active_record/base.rb:2750:in `attributes=' /Users/x/.rvm/gems/ruby-1.8.6-p383/gems/activerecord-2.3.5/lib/active_record/base.rb:2438:in `initialize' Any ideas as to what the problem might be? I've looked at #93277 with no joy, so am kinda stuck. Adding day to the select does NOT resolve the issue. Any ideas?

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