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  • Functional Adaptation

    - by Charles Courchaine
    In real life and OO programming we’re often faced with using adapters, DVI to VGA, 1/4” to 1/8” audio connections, 110V to 220V, wrapping an incompatible interface with a new one, and so on.  Where the adapter pattern is generally considered for interfaces and classes a similar technique can be applied to method signatures.  To be fair, this adaptation is generally used to reduce the number of parameters but I’m sure there are other clever possibilities to be had.  As Jan questioned in the last post, how can we use a common method to execute an action if the action has a differing number of parameters, going back to the greeting example it was suggested having an AddName method that takes a first and last name as parameters.  This is exactly what we’ll address in this post. Let’s set the stage with some review and some code changes.  First, our method that handles the setup/tear-down infrastructure for our WCF service: 1: private static TResult ExecuteGreetingFunc<TResult>(Func<IGreeting, TResult> theGreetingFunc) 2: { 3: IGreeting aGreetingService = null; 4: try 5: { 6: aGreetingService = GetGreetingChannel(); 7: return theGreetingFunc(aGreetingService); 8: } 9: finally 10: { 11: CloseWCFChannel((IChannel)aGreetingService); 12: } 13: } Our original AddName method: 1: private static string AddName(string theName) 2: { 3: return ExecuteGreetingFunc<string>(theGreetingService => theGreetingService.AddName(theName)); 4: } Our new AddName method: 1: private static int AddName(string firstName, string lastName) 2: { 3: return ExecuteGreetingFunc<int>(theGreetingService => theGreetingService.AddName(firstName, lastName)); 4: } Let’s change the AddName method, just a little bit more for this example and have it take the greeting service as a parameter. 1: private static int AddName(IGreeting greetingService, string firstName, string lastName) 2: { 3: return greetingService.AddName(firstName, lastName); 4: } The new signature of AddName using the Func delegate is now Func<IGreeting, string, string, int>, which can’t be used with ExecuteGreetingFunc as is because it expects Func<IGreeting, TResult>.  Somehow we have to eliminate the two string parameters before we can use this with our existing method.  This is where we need to adapt AddName to match what ExecuteGreetingFunc expects, and we’ll do so in the following progression. 1: Func<IGreeting, string, string, int> -> Func<IGreeting, string, int> 2: Func<IGreeting, string, int> -> Func<IGreeting, int>   For the first step, we’ll create a method using the lambda syntax that will “eliminate” the last name parameter: 1: string lastNameToAdd = "Smith"; 2: //Func<IGreeting, string, string, int> -> Func<IGreeting, string, int> 3: Func<IGreeting, string, int> addName = (greetingService, firstName) => AddName(greetingService, firstName, lastNameToAdd); The new addName method gets us one step close to the signature we need.  Let’s say we’re going to call this in a loop to add several names, we’ll take the final step from Func<IGreeting, string, int> -> Func<IGreeting, int> in line as a lambda passed to ExecuteGreetingFunc like so: 1: List<string> firstNames = new List<string>() { "Bob", "John" }; 2: int aID; 3: foreach (string firstName in firstNames) 4: { 5: //Func<IGreeting, string, int> -> Func<IGreeting, int> 6: aID = ExecuteGreetingFunc<int>(greetingService => addName(greetingService, firstName)); 7: Console.WriteLine(GetGreeting(aID)); 8: } If for some reason you needed to break out the lambda on line 6 you could replace it with 1: aID = ExecuteGreetingFunc<int>(ApplyAddName(addName, firstName)); and use this method: 1: private static Func<IGreeting, int> ApplyAddName(Func<IGreeting, string, int> addName, string lastName) 2: { 3: return greetingService => addName(greetingService, lastName); 4: } Splitting out a lambda into its own method is useful both in this style of coding as well as LINQ queries to improve the debugging experience.  It is not strictly necessary to break apart the steps & functions as was shown above; the lambda in line 6 (of the foreach example) could include both the last name and first name instead of being composed of two functions.  The process demonstrated above is one of partially applying functions, this could have also been done with Currying (also see Dustin Campbell’s excellent post on Currying for the canonical curried add example).  Matthew Podwysocki also has some good posts explaining both Currying and partial application and a follow up post that further clarifies the difference between Currying and partial application.  In either technique the ultimate goal is to reduce the number of parameters passed to a function.  Currying makes it a single parameter passed at each step, where partial application allows one to use multiple parameters at a time as we’ve done here.  This technique isn’t for everyone or every problem, but can be extremely handy when you need to adapt a call to something you don’t control.

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  • Should functions of a C library always expect a string's length?

    - by Benjamin Kloster
    I'm currently working on a library written in C. Many functions of this library expect a string as char* or const char* in their arguments. I started out with those functions always expecting the string's length as a size_t so that null-termination wasn't required. However, when writing tests, this resulted in frequent use of strlen(), like so: const char* string = "Ugh, strlen is tedious"; libFunction(string, strlen(string)); Trusting the user to pass properly terminated strings would lead to less safe, but more concise and (in my opinion) readable code: libFunction("I hope there's a null-terminator there!"); So, what's the sensible practice here? Make the API more complicated to use, but force the user to think of their input, or document the requirement for a null-terminated string and trust the caller?

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  • Parsing a Directory of files - Check for a String

    - by i.h4d35
    This is my first post here so kindly pardon any mistakes that I have. I'm still learning to find my way around Stack Exchange. I am trying to write a Java program that tries to scan a Directory full of either .txt,.rtf or.doc files(and none other). The aim is to search all the files in the directory, and find out if a particular string exists in the file. If it does, it returns the string and the filename that it found the string in. The aim of this program is, it is a project for school wherein the program scans the personal folders of call center employees to check if they have stored any CC/DC nos and if yes, report the folder name - to reduce CC fraud. The search function was fairly straight forward and works when I individually specify the filename. However, the searching the directory and passing the files to the search function has me stumped. I've posted my code so far, if you guys could look thru it and give me some feedback/suggestions, I'd really appreciate it. Thanks in advance import java.io.*; import java.util.*; public class parse2{ void traverse(String directory) throws FileNotFoundException { File dir = new File(directory); if (dir.isDirectory()) { String[] children = dir.list(); for (int i=0; i<children.length; i++) { //System.out.println("\n" + children[i]); reader(children[i]); } } } void reader(String loc) throws FileNotFoundException { FileReader fr = new FileReader(loc); BufferedReader br = new BufferedReader(fr); Scanner sc = new Scanner(br); char[] chkArray; int chk=1; char ch; while(sc.hasNext()) { String chkStr = sc.next(); chkArray = chkStr.toCharArray(); if ((chkArray[0]=='4')&&(chkStr.length()>13)) { for(int i=0;i<chkArray.length;i++) { ch=chkArray[i]; if((ch=='0')||(ch=='1')||(ch=='2')||(ch=='3')||(ch=='4')||(ch=='5')||(ch=='6')||(ch=='7')||(ch=='8')||(ch=='9')) { chk=0; continue; } else { chk=1; break; } } if(chk==0) System.out.println("\n"+ chkStr); } else if((chkArray[0]=='5')&&(chkStr.length()>13)) { for(int i=0;i<chkArray.length;i++) { ch=chkArray[i]; if((ch=='0')||(ch=='1')||(ch=='2')||(ch=='3')||(ch=='4')||(ch=='5')||(ch=='6')||(ch=='7')||(ch=='8')||(ch=='9')) { chk=0; continue; } else { chk=1; break; } } if(chk==0) System.out.println("\n"+ chkStr); } else if((chkArray[0]=='6')&&(chkStr.length()>13)) { for(int i=0;i<chkArray.length;i++) { ch=chkArray[i]; if((ch=='0')||(ch=='1')||(ch=='2')||(ch=='3')||(ch=='4')||(ch=='5')||(ch=='6')||(ch=='7')||(ch=='8')||(ch=='9')) { chk=0; continue; } else { chk=1; break; } } if(chk==0) System.out.println("\n"+ chkStr); } } } public static void main(String args[]) throws FileNotFoundException { parse2 P = new parse2(); P.traverse("C:/Documents and Settings/h4d35/Desktop/javatest/chk"); } }

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  • How to map an IDictionary<String, CustomCollectionType> in NHibernate

    - by devonlazarus
    Very close to what I'm trying to do but not quite the answer I think I'm looking for: How to map IDictionary<string, Entity> in Fluent NHibernate I'm trying to implement an IDictionary<String, IList<MyEntity>>and map this collection to the database using NHibernate. I do understand that you cannot map collections of collections directly in NHibernate, but I do need the functionality of accessing an ordered list of elements by key. I've implemented IUserCollectionType for my IList<MyEntity> so that I can use IDictionary<String, MyCustomCollectionType> but am struggling with how to get the map to work as I'd like. Details This is the database I'm trying to model: ------------------------ -------------------- | EntityAttributes | | Entities | ------------------------ ------------------ -------------------- | EntityAttributeId PK | | Attributes | | EntityId PK | <- | EntityId FK | ------------------ | DateCreated | | AttributeId FK | -> | AttributeId PK | -------------------- | AttributeValue | | AttributeName | ------------------------ ------------------ Here are my domain classes: public class Entity { public virtual Int32 Id { get; private set; } public virtual DateTime DateCreated { get; private set; } ... } public class EavEntity : Entity { public virtual IDictionary<String, EavEntityAttributeList> Attributes { get; protected set; } ... } public class EavAttribute : Entity { public virtual String Name { get; set; } ... } public class EavEntityAttribute : Entity { public virtual EavEntity EavEntity { get; private set; } public virtual EavAttribute EavAttribute { get; private set; } public virtual Object AttributeValue { get; set; } ... } public class EavEntityAttributeList : List<EavEntityAttribute> { } I've also implemented the NH-specific custom collection classes IUserCollectionType and PersistentList And here is my mapping so far: <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" ...> <class xmlns="urn:nhibernate-mapping-2.2" name="EavEntity" table="Entities"> <id name="Id" type="System.Int32"> <column name="EntityId" /> <generator class="identity" /> </id> ... <map cascade="all-delete-orphan" collection-type="EavEntityAttributeListType" name="EntityAttributes"> <key> <column name="EntityId" /> </key> <index type="System.String"> <column name="Name" /> </index> <one-to-many class="EavEntityAttributeList" /> </map> </class> </hibernate-mapping> I know the <map> tag is partially correct, but I'm not sure how to get NH to utilize my IUserCollectionType to persist the model to the database. What I'd like to see (and this isn't right, I know) is something like: <map cascade="all-delete-orphan" collection-type="EavEntityAttributeListType" name="EntityAttributes"> <key> <column name="EntityId" /> </key> <index type="System.String"> <column name="Name" /> </index> <list> <index column="DisplayOrder"> <one-to-many class="EntityAttributes"> </list> </map> Does anyone have any suggestions on how to properly map that IDictionary<String, EavEntityAttributeList> collection? I am using Fluent NH so I'll take examples using that library, but I'm hand mappings are just as helpful here.

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  • Trying to convert string to datetime

    - by user1596472
    I am trying to restrict a user from entering a new record if the date requested already exits. I was trying to do a count to see if the table that the record would be placed in already has that date 1 or not 0. I have a calendar extender attached to a text box which has the date. I keep getting either a: String was not recognized as a valid DateTime. or Unable to cast object of type 'System.Web.UI.WebControls.TextBox' to type 'System.IConvertible'. depending on the different things I have tried. Here is my code. TextBox startd = (TextBox)(DetailsView1.FindControl("TextBox5")); TextBox endd = (TextBox)(DetailsView1.FindControl("TextBox7")); DropDownList lvtype = (DropDownList)(DetailsView1.FindControl("DropDownList6")); DateTime scheduledDate = DateTime.ParseExact(startd.Text, "dd/MM/yyyy", null); DateTime endDate = DateTime.ParseExact(endd.Text, "dd/MM/yyyy", null); DateTime newstartDate = Convert.ToDateTime(startd.Text); DateTime newendDate = Convert.ToDateTime(endd.Text); //foreach (DataRow row in sd.Tables[0].Rows) DateTime dt = newstartDate; while (dt <= newendDate) { //for retreiving from table Decimal sd = SelectCountDate(dt, lvtype.SelectedValue, countDate); String ndt = Convert.ToDateTime(dt).ToShortDateString(); // //start = string.CompareOrdinal(scheduledDate, ndt); // // end = string.CompareOrdinal(endDate, ndt); //trying to make say when leavetpe is greater than count 1 then throw error. if (sd > 0) { Response.Write("<script>alert('Date Already Requested');</script>"); } dt.AddDays(1); } ^^^ This version throws the: "String was not recognized as valid date type" error But if i replace the string with either of these : /*-----------------------Original------------------------------------ string scheduledDate = Convert.ToDateTime(endd).ToShortDateString(); string endDate = Convert.ToDateTime(endd).ToShortDateString(); -------------------------------------------------------------------*/ /*----------10-30--------------------------------------- DateTime scheduledDate = DateTime.Parse(startd.Text); DateTime endDate = DateTime.Parse(endd.Text); ------------------------------------------------------*/ I get the "Unable to cast object of type 'System.Web.UI.WebControls.TextBox' to type 'System.IConvertible'." error. I am just trying to stop a user from entering a record date that already exits. <InsertItemTemplate> <asp:TextBox ID="TextBox5" runat="server" Height="19px" Text='<%# Bind("lstdate", "{0:MM/dd/yyyy}") %>' Width="67px"></asp:TextBox> <asp:CalendarExtender ID="TextBox5_CalendarExtender" runat="server" Enabled="True" TargetControlID="TextBox5"> </asp:CalendarExtender> <asp:RequiredFieldValidator ID="RequiredFieldValidator2" runat="server" ControlToValidate="TextBox5" ErrorMessage="*Leave Date Required" ForeColor="Red"></asp:RequiredFieldValidator> <br /> <asp:CompareValidator ID="CompareValidator18" runat="server" ControlToCompare="TextBox7" ControlToValidate="TextBox5" ErrorMessage="Leave date cannot be after start date" ForeColor="Red" Operator="LessThanEqual" ToolTip="Must choose start date before end date"></asp:CompareValidator> </InsertItemTemplate>

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  • Convert Decimal to ASCII

    - by Dan Snyder
    I'm having difficulty using reinterpret_cast. Before I show you my code I'll let you know what I'm trying to do. I'm trying to get a filename from a vector full of data being used by a MIPS I processor I designed. Basically what I do is compile a binary from a test program for my processor, dump all the hex's from the binary into a vector in my c++ program, convert all of those hex's to decimal integers and store them in a DataMemory vector which is the data memory unit for my processor. I also have instruction memory. So When my processor runs a SYSCALL instruction such as "Open File" my C++ operating system emulator receives a pointer to the beginning of the filename in my data memory. So keep in mind that data memory is full of ints, strings, globals, locals, all sorts of stuff. When I'm told where the filename starts I do the following: Convert the whole decimal integer element that is being pointed to to its ASCII character representation, and then search from left to right to see if the string terminates, if not then just load each character consecutively into a "filename" string. Do this until termination of the string in memory and then store filename in a table. My difficulty is generating filename from my memory. Here is an example of what I'm trying to do: C++ Syntax (Toggle Plain Text) 1.Index Vector NewVector ASCII filename 2.0 240faef0 128123792 'abc7' 'a' 3.0 240faef0 128123792 'abc7' 'ab' 4.0 240faef0 128123792 'abc7' 'abc' 5.0 240faef0 128123792 'abc7' 'abc7' 6.1 1234567a 243225 'k2s0' 'abc7k' 7.1 1234567a 243225 'k2s0' 'abc7k2' 8.1 1234567a 243225 'k2s0' 'abc7k2s' 9. //EXIT LOOP// 10.1 1234567a 243225 'k2s0' 'abc7k2s' Index Vector NewVector ASCII filename 0 240faef0 128123792 'abc7' 'a' 0 240faef0 128123792 'abc7' 'ab' 0 240faef0 128123792 'abc7' 'abc' 0 240faef0 128123792 'abc7' 'abc7' 1 1234567a 243225 'k2s0' 'abc7k' 1 1234567a 243225 'k2s0' 'abc7k2' 1 1234567a 243225 'k2s0' 'abc7k2s' //EXIT LOOP// 1 1234567a 243225 'k2s0' 'abc7k2s' Here is the code that I've written so far to get filename (I'm just applying this to element 1000 of my DataMemory vector to test functionality. 1000 is arbitrary.): C++ Syntax (Toggle Plain Text) 1.int i = 0; 2.int step = 1000;//top->a0; 3.string filename; 4.char *temp = reinterpret_cast<char*>( DataMemory[1000] );//convert to char 5.cout << "a0:" << top->a0 << endl;//pointer supplied 6.cout << "Data:" << DataMemory[top->a0] << endl;//my vector at pointed to location 7.cout << "Data(1000):" << DataMemory[1000] << endl;//the element I'm testing 8.cout << "Characters:" << &temp << endl;//my temporary char array 9. 10.while(&temp[i]!=0) 11.{ 12. filename+=temp[i];//add most recent non-terminated character to string 13. i++; 14. if(i==4)//when 4 chatacters have been added.. 15. { 16. i=0; 17. step+=1;//restart loop at the next element in DataMemory 18. temp = reinterpret_cast<char*>( DataMemory[step] ); 19. } 20. } 21. cout << "Filename:" << filename << endl; int i = 0; int step = 1000;//top-a0; string filename; char *temp = reinterpret_cast( DataMemory[1000] );//convert to char cout << "a0:" << top-a0 << endl;//pointer supplied cout << "Data:" << DataMemory[top-a0] << endl;//my vector at pointed to location cout << "Data(1000):" << DataMemory[1000] << endl;//the element I'm testing cout << "Characters:" << &temp << endl;//my temporary char array while(&temp[i]!=0) { filename+=temp[i];//add most recent non-terminated character to string i++; if(i==3)//when 4 chatacters have been added.. { i=0; step+=1;//restart loop at the next element in DataMemory temp = reinterpret_cast( DataMemory[step] ); } } cout << "Filename:" << filename << endl; So the issue is that when I do the conversion of my decimal element to a char array I assume that 8 hex #'s will give me 4 characters. Why isn't this this case? Here is my output: C++ Syntax (Toggle Plain Text) 1.a0:0 2.Data:0 3.Data(1000):4428576 4.Characters:0x7fff5fbff128 5.Segmentation fault

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  • JNI String Corruption

    - by Chris Dennett
    Hi everyone, I'm getting weird string corruption across JNI calls which is causing problems on the the Java side. Every so often, I'll get a corrupted string in the passed array, which sometimes has existing parts of the original non-corrupted string. The C++ code is supposed to set the first index of the array to the address, it's a nasty hack to get around method call limitations. Additionally, the application is multi-threaded. remoteaddress[0]: 10.1.1.2:49153 remoteaddress[0]: 10.1.4.2:49153 remoteaddress[0]: 10.1.6.2:49153 remoteaddress[0]: 10.1.2.2:49153 remoteaddress[0]: 10.1.9.2:49153 remoteaddress[0]: {garbage here} java.lang.NullPointerException at kokuks.KKSAddress.<init>(KKSAddress.java:139) at kokuks.KKSAddress.createAddress(KKSAddress.java:48) at kokuks.KKSSocket._recvFrom(KKSSocket.java:963) at kokuks.scheduler.RecvOperation$1.execute(RecvOperation.java:144) at kokuks.scheduler.RecvOperation$1.execute(RecvOperation.java:1) at kokuks.KKSEvent.run(KKSEvent.java:58) at kokuks.KokuKS.handleJNIEventExpiry(KokuKS.java:872) at kokuks.KokuKS.handleJNIEventExpiry_fjni(KokuKS.java:880) at kokuks.KokuKS.runSimulator_jni(Native Method) at kokuks.KokuKS$1.run(KokuKS.java:773) at java.lang.Thread.run(Thread.java:717) remoteaddress[0]: 10.1.7.2:49153 The null pointer exception comes from trying to use the corrupt string. In C++, the address prints to standard out normally, but doing this reduces the rate of errors, from what I can see. The C++ code (if it helps): /* * Class: kokuks_KKSSocket * Method: recvFrom_jni * Signature: (Ljava/lang/String;[Ljava/lang/String;Ljava/nio/ByteBuffer;IIJ)I */ JNIEXPORT jint JNICALL Java_kokuks_KKSSocket_recvFrom_1jni (JNIEnv *env, jobject obj, jstring sockpath, jobjectArray addrarr, jobject buf, jint position, jint limit, jlong flags) { if (addrarr && env->GetArrayLength(addrarr) > 0) { env->SetObjectArrayElement(addrarr, 0, NULL); } jboolean iscopy; const char* cstr = env->GetStringUTFChars(sockpath, &iscopy); std::string spath = std::string(cstr); env->ReleaseStringUTFChars(sockpath, cstr); // release me! if (KKS_DEBUG) { std::cout << "[kks-c~" << spath << "] " << __PRETTY_FUNCTION__ << std::endl; } ns3::Ptr<ns3::Socket> socket = ns3::Names::Find<ns3::Socket>(spath); if (!socket) { std::cout << "[kks-c~" << spath << "] " << __PRETTY_FUNCTION__ << " socket not found for path!!" << std::endl; return -1; // not found } if (!addrarr) { std::cout << "[kks-c~" << spath << "] " << __PRETTY_FUNCTION__ << " array to set sender is null" << std::endl; return -1; } jsize arrsize = env->GetArrayLength(addrarr); if (arrsize < 1) { std::cout << "[kks-c~" << spath << "] " << __PRETTY_FUNCTION__ << " array too small to set sender!" << std::endl; return -1; } uint8_t* bufaddr = (uint8_t*)env->GetDirectBufferAddress(buf); long bufcap = env->GetDirectBufferCapacity(buf); uint8_t* realbufaddr = bufaddr + position; uint32_t remaining = limit - position; if (KKS_DEBUG) { std::cout << "[kks-c~" << spath << "] " << __PRETTY_FUNCTION__ << " bufaddr: " << bufaddr << ", cap: " << bufcap << std::endl; } ns3::Address aaddr; uint32_t mflags = flags; int ret = socket->RecvFrom(realbufaddr, remaining, mflags, aaddr); if (ret > 0) { if (KKS_DEBUG) std::cout << "[kks-c~" << spath << "] " << __PRETTY_FUNCTION__ << " addr: " << aaddr << std::endl; ns3::InetSocketAddress insa = ns3::InetSocketAddress::ConvertFrom(aaddr); std::stringstream ss; insa.GetIpv4().Print(ss); ss << ":" << insa.GetPort() << std::ends; if (KKS_DEBUG) std::cout << "[kks-c~" << spath << "] " << __PRETTY_FUNCTION__ << " addr: " << ss.str() << std::endl; jsize index = 0; const char *cstr = ss.str().c_str(); jstring jaddr = env->NewStringUTF(cstr); if (jaddr == NULL) std::cout << "[kks-c~" << spath << "] " << __PRETTY_FUNCTION__ << " jaddr is null!!" << std::endl; //jaddr = (jstring)env->NewGlobalRef(jaddr); env->SetObjectArrayElement(addrarr, index, jaddr); //if (env->ExceptionOccurred()) { // env->ExceptionDescribe(); //} } jint jret = ret; return jret; } The Java code (if it helps): /** * Pass an array of size 1 into remote address, and this will be set with * the sender of the packet (hax). This emulates C++ references. * * @param remoteaddress * @param buf * @param flags * @return */ public int _recvFrom(final KKSAddress remoteaddress[], ByteBuffer buf, long flags) { if (!kks.isCurrentlyThreadSafe()) throw new RuntimeException( "Not currently thread safe for ns-3 functions!" ); //lock.lock(); try { if (!buf.isDirect()) return -6; // not direct!! final String[] remoteAddrStr = new String[1]; int ret = 0; ret = recvFrom_jni( path.toPortableString(), remoteAddrStr, buf, buf.position(), buf.limit(), flags ); if (ret > 0) { System.out.println("remoteaddress[0]: " + remoteAddrStr[0]); remoteaddress[0] = KKSAddress.createAddress(remoteAddrStr[0]); buf.position(buf.position() + ret); } return ret; } finally { errNo = _getErrNo(); //lock.unlock(); } } public int recvFrom(KKSAddress[] fromaddress, final ByteBuffer bytes, long flags, long timeoutMS) { if (KokuKS.DEBUG_MODE) printMessage("public synchronized int recvFrom(KKSAddress[] fromaddress, final ByteBuffer bytes, long flags, long timeoutMS)"); if (kks.isCurrentlyThreadSafe()) { return _recvFrom(fromaddress, bytes, flags); // avoid event } fromaddress[0] = null; RecvOperation ro = new RecvOperation( kks, this, flags, true, bytes, timeoutMS ); ro.start(); fromaddress[0] = ro.getFrom(); return ro.getRetCode(); }

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  • Accessing different connection strings at runtime in ASP.NET MVC 1

    - by Neil T.
    I'm trying to implement integration testing in my ASP.NET MVC 1.0 solution. The technologies in use are LINQ-to-SQL, NUnit and WatiN. I recently discovered a pattern that will allow me to create a testing version of the database on the fly without modifying the development version of the database. I needed this behavior in order to run my user interface tests in WatiN that may modify the database. The plan is to modify the connection string in the Web.config file, and pass that new connection string to the DataContext constructor. This way, I don't have to add routes or modify my URLs in order to perform the integration testing. I've set up the project so that the test setup can modify the connection string to point to the test database when the tests are running. The connection string is stored in web.config. The problem I'm having is that when I try to run the tests, I get a NullReferenceException when trying to access the HTTPContext. From everything that I have read so far, the HTTPContext is only available within the context of a controller. Here is the code for the property that is supposed to give me the reference to the Web.config file: private System.Configuration.Configuration WebConfig { get { ExeConfigurationFileMap fileMap = new ExeConfigurationFileMap(); // NullReferenceException occurs on this line. fileMap.ExeConfigFilename = HttpContext.Current.Server.MapPath("~\\web.config"); System.Configuration.Configuration config = ConfigurationManager.OpenMappedExeConfiguration(fileMap, ConfigurationUserLevel.None); return config; } } Is there something that I am missing in order to make this work? Is there a better way to accomplish what I'm trying to achieve? UPDATE: I decided to abandon the modification of Web.config in lieu of a "request-scoped DataContext" pattern that I found here. From the looks of it, I believe it should give me the results I'm looking for. However, during the TextFixtureSetUp, I try to create a new copy of the database for testing purposes, and it fails silently. When I get to the tests, the repository still uses the production database connection string to load data.

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  • Changing text depending on rounded total from database

    - by NeonBlue Bliss
    On a website I have a number of small PHP scripts to automate changes to the text of the site, depending on a figure that's calculated from a MySQL database. The site is for a fundraising group, and the text in question on the home page gives the total amount raised. The amount raised is pulled from the database and rounded to the nearest thousand. This is the PHP I use to round the figure and find the last three digits of the total: $query4 = mysql_query("SELECT SUM(amountraised) AS full_total FROM fundraisingtotal;"); $result4 = mysql_fetch_array($query4); $fulltotal = $result4["full_total"]; $num = $fulltotal + 30000; $ftotalr = round($num,-3); $roundnum = round($num); $string = $roundnum; $length = strlen($string); $characters = 3; $start = $length - $characters; $string = substr($string , $start ,$characters); $figure = $string; (£30,000 is the amount that had been raised by the previous fundraising team from when the project first started, which is why I've added 30000 to $fulltotal for the $num variable) Currently the text reads: the bookstall and other fundraising events have raised more than &pound;<? echo number_format($ftotalr); ?> I've just realised though that because the PHP is rounding to the nearest thousand, if the total's for example £39,200 and it's rounded to £40,000, to say it's more than £40,000 is incorrect, and in that case I'd need it to say 'almost £40,000' or something similar. I obviously need to replace the 'more than' with a variable. Obviously I need to test whether the last three digits of the total are nearer to 0 or 1000, so that if the total was for example £39,2000, the text would read 'just over', if it was between £39,250 and £39,400 something like 'over', between £39,400 and £39,700 something like 'well over', and between £39,700 and £39,999, 'almost.' I've managed to get the last three digits of the total as a variable, and I think I need some sort of an if/else/elseif code block (not sure if that would be the right approach, or whether to use case/break), and obviously I'm going to have to check whether the figure meets each of the criteria, but I can't figure out how to do that. Could anyone suggest what would be the best way to do this please?

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  • C++ Exam Question

    - by Carlucho
    I just took an exam where i was asked the following: Write the function body of each of the methods GenStrLen, InsertChar and StrReverse for the given code bellow. You must take into consideration the following; How strings are constructed in C++ The string must not overflow Insertion of character increases its length by 1 An empty string is indicated by StrLen = 0 class Strings { private: char str[80]; int StrLen; public: // Constructor Strings() { StrLen=0; }; // A function for returning the length of the string 'str' int GetStrLen(void) { }; // A function to inser a character 'ch' at the end of the string 'str' void InsertChar(char ch) { }; // A function to reverse the content of the string 'str' void StrReverse(void) { }; }; The answer I gave was something like this (see bellow). My one of problem is that used many extra variables and that makes me believe am not doing it the best possible way, and the other thing is that is not working.... class Strings { private: char str[80]; int StrLen; int index; // *** Had to add this *** public: Strings(){ StrLen=0; } int GetStrLen(void){ for (int i=0 ; str[i]!='\0' ; i++) index++; return index; // *** Here am getting a weird value, something like 1829584505306 *** } void InsertChar(char ch){ str[index] = ch; // *** Not sure if this is correct cuz I was not given int index *** } void StrRevrse(void){ GetStrLen(); char revStr[index+1]; for (int i=0 ; str[i]!='\0' ; i++){ for (int r=index ; r>0 ; r--) revStr[r] = str[i]; } } }; I would appreciate if anyone could explain me toughly what is the best way to have answered the question and why. Also how come my professor closes each class function like " }; " i thought that was only used for ending classes and constructors only. Thanks a lot for your help.

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  • Marshalling non-Blittable Structs from C# to C++

    - by Greggo
    I'm in the process of rewriting an overengineered and unmaintainable chunk of my company's library code that interfaces between C# and C++. I've started looking into P/Invoke, but it seems like there's not much in the way of accessible help. We're passing a struct that contains various parameters and settings down to unmanaged codes, so we're defining identical structs. We don't need to change any of those parameters on the C++ side, but we do need to access them after the P/Invoked function has returned. My questions are: What is the best way to pass strings? Some are short (device id's which can be set by us), and some are file paths (which may contain Asian characters) Should I pass an IntPtr to the C# struct or should I just let the Marshaller take care of it by putting the struct type in the function signature? Should I be worried about any non-pointer datatypes like bools or enums (in other, related structs)? We have the treat warnings as errors flag set in C++ so we can't use the Microsoft extension for enums to force a datatype. Is P/Invoke actually the way to go? There was some Microsoft documentation about Implicit P/Invoke that said it was more type-safe and performant. For reference, here is one of the pairs of structs I've written so far: C++ /** Struct used for marshalling Scan parameters from managed to unmanaged code. */ struct ScanParameters { LPSTR deviceID; LPSTR spdClock; LPSTR spdStartTrigger; double spinRpm; double startRadius; double endRadius; double trackSpacing; UINT64 numTracks; UINT32 nominalSampleCount; double gainLimit; double sampleRate; double scanHeight; LPWSTR qmoPath; //includes filename LPWSTR qzpPath; //includes filename }; C# /// <summary> /// Struct used for marshalling scan parameters between managed and unmanaged code. /// </summary> [StructLayout(LayoutKind.Sequential)] public struct ScanParameters { [MarshalAs(UnmanagedType.LPStr)] public string deviceID; [MarshalAs(UnmanagedType.LPStr)] public string spdClock; [MarshalAs(UnmanagedType.LPStr)] public string spdStartTrigger; public Double spinRpm; public Double startRadius; public Double endRadius; public Double trackSpacing; public UInt64 numTracks; public UInt32 nominalSampleCount; public Double gainLimit; public Double sampleRate; public Double scanHeight; [MarshalAs(UnmanagedType.LPWStr)] public string qmoPath; [MarshalAs(UnmanagedType.LPWStr)] public string qzpPath; }

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  • [C++] std::tring manipulation: whitespace, "newline escapes '\'" and comments #

    - by rubenvb
    Kind of looking for affirmation here. I have some hand-written code, which I'm not shy to say I'm proud of, which reads a file, removes leading whitespace, processes newline escapes '\' and removes comments starting with #. It also removes all empty lines (also whitespace-only ones). Any thoughts/recommendations? I could probably replace some std::cout's with std::runtime_errors... but that's not a priority here :) const int RecipeReader::readRecipe() { ifstream is_recipe(s_buffer.c_str()); if (!is_recipe) cout << "unable to open file" << endl; while (getline(is_recipe, s_buffer)) { // whitespace+comment removeLeadingWhitespace(s_buffer); processComment(s_buffer); // newline escapes + append all subsequent lines with '\' processNewlineEscapes(s_buffer, is_recipe); // store the real text line if (!s_buffer.empty()) v_s_recipe.push_back(s_buffer); s_buffer.clear(); } is_recipe.close(); return 0; } void RecipeReader::processNewlineEscapes(string &s_string, ifstream &is_stream) { string s_temp; size_t sz_index = s_string.find_first_of("\\"); while (sz_index <= s_string.length()) { if (getline(is_stream,s_temp)) { removeLeadingWhitespace(s_temp); processComment(s_temp); s_string = s_string.substr(0,sz_index-1) + " " + s_temp; } else cout << "Error: newline escape '\' found at EOF" << endl; sz_index = s_string.find_first_of("\\"); } } void RecipeReader::processComment(string &s_string) { size_t sz_index = s_string.find_first_of("#"); s_string = s_string.substr(0,sz_index); } void RecipeReader::removeLeadingWhitespace(string &s_string) { const size_t sz_length = s_string.size(); size_t sz_index = s_string.find_first_not_of(" \t"); if (sz_index <= sz_length) s_string = s_string.substr(sz_index); else if ((sz_index > sz_length) && (sz_length != 0)) // "empty" lines with only whitespace s_string.clear(); } Some extra info: std::string s_buffer is a class data member, so is std::vector v_s_recipe. Any comment is welcome :)

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  • Java looping through array - Optimization

    - by oudouz
    I've got some Java code that runs quite the expected way, but it's taking some amount of time -some seconds- even if the job is just looping through an array. The input file is a Fasta file as shown in the image below. The file I'm using is 2.9Mo, and there are some other Fasta file that can take up to 20Mo. And in the code im trying to loop through it by bunches of threes, e.g: AGC TTT TCA ... etc The code has no functional sens for now but what I want is to append each Amino Acid to it's equivalent bunch of Bases. Example : AGC - Ser / CUG Leu / ... etc So what's wrong with the code ? and Is there any way to do it better ? Any optimization ? Looping through the whole String is taking some time, maybe just seconds, but need to find a better way to do it. import java.io.BufferedReader; import java.io.File; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.IOException; public class fasta { public static void main(String[] args) throws IOException { File fastaFile; FileReader fastaReader; BufferedReader fastaBuffer = null; StringBuilder fastaString = new StringBuilder(); try { fastaFile = new File("res/NC_017108.fna"); fastaReader = new FileReader(fastaFile); fastaBuffer = new BufferedReader(fastaReader); String fastaDescription = fastaBuffer.readLine(); String line = fastaBuffer.readLine(); while (line != null) { fastaString.append(line); line = fastaBuffer.readLine(); } System.out.println(fastaDescription); System.out.println(); String currentFastaAcid; for (int i = 0; i < fastaString.length(); i+=3) { currentFastaAcid = fastaString.toString().substring(i, i + 3); System.out.println(currentFastaAcid); } } catch (NullPointerException e) { System.out.println(e.getMessage()); } catch (FileNotFoundException e) { System.out.println(e.getMessage()); } catch (IOException e) { System.out.println(e.getMessage()); } finally { fastaBuffer.close(); } } }

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  • Searching strings C

    - by Skittles
    First time posting here so I'm sorry if I mess up. I need to search a string and return any strings containing the search data with the search data highlighted. If my string is Hi my name is and I searched name it would produce Hi my NAME is This is a quick code I wrote that works but it only works once. If I try and search again it seg faults. I was hoping someone could hint me at a better way to write this because this code is disgusting! void search(char * srcStr, int n){ int cnt = 0, pnt,i = 0; char tmpText[500]; char tmpName[500]; char *ptr, *ptr2, *ptrLast; int num; while(*(node->text+cnt) != '\0'){ //finds length of string cnt++; } for(pnt = 0; pnt < cnt; pnt++){ //copies node->text into a tmp string tmpText[pnt] = *(node->text+pnt); } tmpText[pnt+1] = '\0'; //prints up to first occurrence of srcStr ptr = strcasestr(tmpText, srcStr); for(num = 0; num < ptr-tmpText; num++){ printf("%c",tmpText[num]); } //prints first occurrence of srcStr in capitals for(num = 0; num < n; num++){ printf("%c",toupper(tmpText[ptr-tmpText+num])); } ptr2 = strcasestr((ptr+n),srcStr); for(num = (ptr-tmpText+n); num < (ptr2-tmpText); num++){ printf("%c",tmpText[num]); } while((ptr = strcasestr((ptr+n), srcStr)) != NULL){ ptr2 = strcasestr((ptr+n),srcStr); for(num = (ptr-tmpText+n); num < (ptr2-tmpText); num++){ printf("%c",tmpText[num]); } for(num = 0; num < n; num++){ printf("%c",toupper(tmpText[ptr-tmpText+num])); } ptrLast = ptr; } //prints remaining string after last occurrence for(num = (ptrLast-tmpText+n); num < cnt; num++){ printf("%c",tmpText[num]); } }

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  • Find files containing a string on the whole filesystem

    - by Fabio
    I need to find all the instances of a given string in the whole filesystem, because I don't remember in which configuration files, script or any other programs I put it and I need to update that string with a new one. I tried with the following command `grep -nr 'needle' / --exclude-dir=.svn | mail [email protected] -s 'References on xxx' If I run this command on a small directory it gives me the output I need in the form /path1/:nn:line containing needle /path2/:nn:line containing needle where /path1 is the full path of the file, nn is the row containing the needle and last field is the content of the line. However when I run the command on the root directory the grep process hang after a while. I run this script about 8 hours ago and even on a small filesystem (less than 5GB) it doesn't end and if I run top or ps the process seems sleeping root 24909 0.0 0.1 3772 1520 pts/1 S+ Feb10 0:15 grep -nr needle / --exclude-dir=.svn Why it doesn't end? Is there any better way to do this (it's a one time job, I don't need to execute this more than once) Thanks.

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  • IIS Url Rewrite Capturing query string and escaping characters

    - by LiamB
    We are just adding some redirects for an old site to a new one in IIS7 using the URL Rewrite 'plugin'. The old site's URL are all based on the query string, we'd usually do explicit rewrites like below. But this wont work in the case of the query string. <rule name="Redirect-1" patternSyntax="Wildcard" stopProcessing="true"> <match url="index.php?option=m_content&view=article&id=15&Itemid=16" /> <action type="Redirect" url="http://newurl/some-page" /> </rule> So using the 2 URL's above how can we do a 301 redirect?

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  • How to rename everything matching a certain string in a folder

    - by lostiniceland
    Hello Everyone I am running Linux and I have some basic console knowledge but my current problem is quite difficult and I dont know how to achieve this. I want/need to rename everything within a folder that matches a given string. By everything I mean folders/files content within a file content in hidden files Basically I want to refactor a Java-project. Sure, I could use Eclipse to handle the replacing, but this leaves out the folders or resources outside of my workspace. I was thinking of a script that could do the job for me but this seems rather tricky. For instance when it comes to folder-/file-rename I want to replace only the part of the name that matches my string, the rest should remain untouched. Maybe someone already has something like this in his/her script-collection :-) Thanks in advance Marc

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  • How to rename everything matching a certain string in a folder

    - by lostiniceland
    Hello Everyone I am running Linux and I have some basic console knowledge but my current problem is quite difficult and I dont know how to achieve this. I want/need to rename everything within a folder that matches a given string. By everything I mean folders/files content within a file content in hidden files Basically I want to refactor a Java-project. Sure, I could use Eclipse to handle the replacing, but this leaves out the folders or resources outside of my workspace. I was thinking of a script that could do the job for me but this seems rather tricky. For instance when it comes to folder-/file-rename I want to replace only the part of the name that matches my string, the rest should remain untouched. Maybe someone already has something like this in his/her script-collection :-) Thanks in advance Marc

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  • Criteria strings, how many different criteria can be entered to retrieve specific data?

    - by Janet
    For our membership database we are currently using an old DOS program "Arclist". The program is old but the one feature we desperately need in a database program is to be able to enter multiple criteria at one time for more of a "one time" extraction of the data meeting all the various criteria entered in what I call a "criteria string". An example may be extracting only those records with zip codes matching (67893, 54235, 54323, 54201, 54302, 54303, 54301, 67894, 67895). Another set of criteria might be to omit records, not equal to, one type of criteria in one field and also extract records matching criteria in another field. So we would want records "not equal to" in one field, but whose information equals requested information in another field.

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  • Highlight identical strings in vi(m)

    - by Boldewyn
    One feature of Notepad++, which I find really useful and haven't found elsewhere, is the highlighting of other text that is identical to the one currently selected. Is there something similar possible with vi(m)? (Of course, there is. But how do I achieve it?) That is, any of those: If I am in Visual Mode and have text selected: Highlight identical text If I have searched /foo, highlight all instances of foo. If I am at the beginning of a string (series of characters, numbers or underscores), highlight all other matching strings (prefered solution). The last one is similar to the closing parentheses matching and IMHO the most useful. Edit: For my second use case, I found a solution (that is, Google found it...): :set hls However, the others remain.

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  • Automatically send a string when opening a raw connection in putty

    - by MBraedley
    I have a program running on a server that accepts TCP/IP connections on a specified port. When a connection is made, this program waits for the user (i.e. me) to send a string which identifies the type of user. Once the user identifies themselves, the program will start sending data that is relevant to that user type. I want to automate the first step and have putty automatically send the user identification string once the connection is made. I've been through the settings, and can't seem to find anything like "send following commands on connection". Any help would be appreciated.

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  • Command output as string

    - by rik
    I want to get output from command C:\Program Files (x86)\Java\jre7\bin\java.exe" -version as string variable. I tried this way: $out = &"C:\Program Files (x86)\Java\jre7\bin\java.exe" -version but it gives error message: java.exe : java version "1.7.0_05" At line:1 char:9 + $out = & <<<< "C:\Program Files (x86)\Java\jre7\bin\java.exe" -version + CategoryInfo : NotSpecified: (java version "1.7.0_05":String) [], RemoteException + FullyQualifiedErrorId : NativeCommandError Java(TM) SE Runtime Environment (build 1.7.0_05-b05) Java HotSpot(TM) Client VM (build 23.1-b03, mixed mode, sharing) $out variable seems empty. What am I doing wrong?

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  • The Return Of __FILE__ And __LINE__ In .NET 4.5

    - by Alois Kraus
    Good things are hard to kill. One of the most useful predefined compiler macros in C/C++ were __FILE__ and __LINE__ which do expand to the compilation units file name and line number where this value is encountered by the compiler. After 4.5 versions of .NET we are on par with C/C++ again. It is of course not a simple compiler expandable macro it is an attribute but it does serve exactly the same purpose. Now we do get CallerLineNumberAttribute  == __LINE__ CallerFilePathAttribute        == __FILE__ CallerMemberNameAttribute  == __FUNCTION__ (MSVC Extension)   The most important one is CallerMemberNameAttribute which is very useful to implement the INotifyPropertyChanged interface without the need to hard code the name of the property anymore. Now you can simply decorate your change method with the new CallerMemberName attribute and you get the property name as string directly inserted by the C# compiler at compile time.   public string UserName { get { return _userName; } set { _userName=value; RaisePropertyChanged(); // no more RaisePropertyChanged(“UserName”)! } } protected void RaisePropertyChanged([CallerMemberName] string member = "") { var copy = PropertyChanged; if(copy != null) { copy(new PropertyChangedEventArgs(this, member)); } } Nice and handy. This was obviously the prime reason to implement this feature in the C# 5.0 compiler. You can repurpose this feature for tracing to get your hands on the method name of your caller along other stuff very fast now. All infos are added during compile time which is much faster than other approaches like walking the stack. The example on MSDN shows the usage of this attribute with an example public static void TraceMessage(string message, [CallerMemberName] string memberName = "", [CallerFilePath] string sourceFilePath = "", [CallerLineNumber] int sourceLineNumber = 0) { Console.WriteLine("Hi {0} {1} {2}({3})", message, memberName, sourceFilePath, sourceLineNumber); }   When I do think of tracing I do usually want to have a API which allows me to Trace method enter and leave Trace messages with a severity like Info, Warning, Error When I do print a trace message it is very useful to print out method and type name as well. So your API must either be able to pass the method and type name as strings or extract it automatically via walking back one Stackframe and fetch the infos from there. The first glaring deficiency is that there is no CallerTypeAttribute yet because the C# compiler team was not satisfied with its performance.   A usable Trace Api might therefore look like   enum TraceTypes { None = 0, EnterLeave = 1 << 0, Info = 1 << 1, Warn = 1 << 2, Error = 1 << 3 } class Tracer : IDisposable { string Type; string Method; public Tracer(string type, string method) { Type = type; Method = method; if (IsEnabled(TraceTypes.EnterLeave,Type, Method)) { } } private bool IsEnabled(TraceTypes traceTypes, string Type, string Method) { // Do checking here if tracing is enabled return false; } public void Info(string fmt, params object[] args) { } public void Warn(string fmt, params object[] args) { } public void Error(string fmt, params object[] args) { } public static void Info(string type, string method, string fmt, params object[] args) { } public static void Warn(string type, string method, string fmt, params object[] args) { } public static void Error(string type, string method, string fmt, params object[] args) { } public void Dispose() { // trace method leave } } This minimal trace API is very fast but hard to maintain since you need to pass in the type and method name as hard coded strings which can change from time to time. But now we have at least CallerMemberName to rid of the explicit method parameter right? Not really. Since any acceptable usable trace Api should have a method signature like Tracexxx(… string fmt, params [] object args) we not able to add additional optional parameters after the args array. If we would put it before the format string we would need to make it optional as well which would mean the compiler would need to figure out what our trace message and arguments are (not likely) or we would need to specify everything explicitly just like before . There are ways around this by providing a myriad of overloads which in the end are routed to the very same method but that is ugly. I am not sure if nobody inside MS agrees that the above API is reasonable to have or (more likely) that the whole talk about you can use this feature for diagnostic purposes was not a core feature at all but a simple byproduct of making the life of INotifyPropertyChanged implementers easier. A way around this would be to allow for variable argument arrays after the params keyword another set of optional arguments which are always filled by the compiler but I do not know if this is an easy one. The thing I am missing much more is the not provided CallerType attribute. But not in the way you would think of. In the API above I did add some filtering based on method and type to stay as fast as possible for types where tracing is not enabled at all. It should be no more expensive than an additional method call and a bool variable check if tracing for this type is enabled at all. The data is tightly bound to the calling type and method and should therefore become part of the static type instance. Since extending the CLR type system for tracing is not something I do expect to happen I have come up with an alternative approach which allows me basically to attach run time data to any existing type object in super fast way. The key to success is the usage of generics.   class Tracer<T> : IDisposable { string Method; public Tracer(string method) { if (TraceData<T>.Instance.Enabled.HasFlag(TraceTypes.EnterLeave)) { } } public void Dispose() { if (TraceData<T>.Instance.Enabled.HasFlag(TraceTypes.EnterLeave)) { } } public static void Info(string fmt, params object[] args) { } /// <summary> /// Every type gets its own instance with a fresh set of variables to describe the /// current filter status. /// </summary> /// <typeparam name="T"></typeparam> internal class TraceData<UsingType> { internal static TraceData<UsingType> Instance = new TraceData<UsingType>(); public bool IsInitialized = false; // flag if we need to reinit the trace data in case of reconfigured trace settings at runtime public TraceTypes Enabled = TraceTypes.None; // Enabled trace levels for this type } } We do not need to pass the type as string or Type object to the trace Api. Instead we define a generic Api that accepts the using type as generic parameter. Then we can create a TraceData static instance which is due to the nature of generics a fresh instance for every new type parameter. My tests on my home machine have shown that this approach is as fast as a simple bool flag check. If you have an application with many types using tracing you do not want to bring the app down by simply enabling tracing for one special rarely used type. The trace filter performance for the types which are not enabled must be therefore the fasted code path. This approach has the nice side effect that if you store the TraceData instances in one global list you can reconfigure tracing at runtime safely by simply setting the IsInitialized flag to false. A similar effect can be achieved with a global static Dictionary<Type,TraceData> object but big hash tables have random memory access semantics which is bad for cache locality and you always need to pay for the lookup which involves hash code generation, equality check and an indexed array access. The generic version is wicked fast and allows you to add more features to your tracing Api with minimal perf overhead. But it is cumbersome to write the generic type argument always explicitly and worse if you do refactor code and move parts of it to other classes it might be that you cannot configure tracing correctly. I would like therefore to decorate my type with an attribute [CallerType] class Tracer<T> : IDisposable to tell the compiler to fill in the generic type argument automatically. class Program { static void Main(string[] args) { using (var t = new Tracer()) // equivalent to new Tracer<Program>() { That would be really useful and super fast since you do not need to pass any type object around but you do have full type infos at hand. This change would be breaking if another non generic type exists in the same namespace where now the generic counterpart would be preferred. But this is an acceptable risk in my opinion since you can today already get conflicts if two generic types of the same name are defined in different namespaces. This would be only a variation of this issue. When you do think about this further you can add more features like to trace the exception in your Dispose method if the method is left with an exception with that little trick I did write some time ago. You can think of tracing as a super fast and configurable switch to write data to an output destination or to execute alternative actions. With such an infrastructure you can e.g. Reconfigure tracing at run time. Take a memory dump when a specific method is left with a specific exception. Throw an exception when a specific trace statement is hit (useful for testing error conditions). Execute a passed delegate which e.g. dumps additional state when enabled. Write data to an in memory ring buffer and dump it when specific events do occur (e.g. method is left with an exception, triggered from outside). Write data to an output device. …. This stuff is really useful to have when your code is in production on a mission critical server and you need to find the root cause of sporadic crashes of your application. It could be a buggy graphics card driver which throws access violations into your application (ok with .NET 4 not anymore except if you enable a compatibility flag) where you would like to have a minidump or you have reached after two weeks of operation a state where you need a full memory dump at a specific point in time in the middle of an transaction. At my older machine I do get with this super fast approach 50 million traces/s when tracing is disabled. When I do know that tracing is enabled for this type I can walk the stack by using StackFrameHelper.GetStackFramesInternal to check further if a specific action or output device is configured for this method which is about 2-3 times faster than the regular StackTrace class. Even with one String.Format I am down to 3 million traces/s so performance is not so important anymore since I do want to do something now. The CallerMemberName feature of the C# 5 compiler is nice but I would have preferred to get direct access to the MethodHandle and not to the stringified version of it. But I really would like to see a CallerType attribute implemented to fill in the generic type argument of the call site to augment the static CLR type data with run time data.

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  • C++ 'using': Should I use it or should I avoid it?

    - by Mehrdad
    I realize there are subtly different semantics for some of these, because of ADL. In general, though: Which one should I prefer (if any), and why? (Or does it depend on the situation (e.g. inline header vs. implementation?) Also: should I prefer ::std:: over std::? using namespace std; pair<string::const_iterator, string::const_iterator> f(const string &s) { return make_pair(s.begin(), s.end()); } or std::pair<std::string::const_iterator, std::string::const_iterator> f(const std::string &s) { return std::make_pair(s.begin(), s.end()); } or using std::pair; using std::string; pair<string::const_iterator, string::const_iterator> f(const string &s) { return make_pair(s.begin(), s.end()); } or std::pair<std::string::const_iterator, std::string::const_iterator> f(const std::string &s) { using std::make_pair; return make_pair(s.begin(), s.end()); } or std::pair<std::string::const_iterator, std::string::const_iterator> f(const std::string &s) { using namespace std; return make_pair(s.begin(), s.end()); } or something else? (This is assuming I don't have C++11 and auto.)

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