4 sintax problems in C#: can you help?

1) how do you invoke a constructor *inside* some other consrtuctor class X{ public X(int i) {...} public X(int j, string s) { X(j); ... } //wont compile } 2) is it possible to define methods with default values à là C++? class X{ public X(int i) {...} public void abc(int j, int k=0, string s="") { ... } /* overloaded forms: public void abc(int j) { ... } public void abc(int j, int k) { ... } public void abc(int j, int k, string s) { ... } */ } 3) how do you run code as soon as a class is loaded? something like: class X{ static { //run as soon as the class is loaded int i=0; ... } public X(int i) {...} } 4) how to force the redefinition of a static method in a derivate class? //>>>>>abstract class to avoid instanciation public abstract class DataStorage { protected static IDbConnection cn; protected static DataStorage db; protected IDataReader dr; protected IDbCommand cmd; //create & ini cn HERE(provide a conn strin here!) //>>>>>abstract to force its redefinition in a derivate class - wont compile bc its static... protected static abstract bool IniciateConnection(); //create & ini dr, cmd, ... //>>>>>abstract to force its redefinition in a derivate class protected abstract void IniciateInstanceObjects(); private DataStorage() { //private to create singleton? IniciateInstanceObjects(); } public static DataStorage GetInstance() { if (cn==null) IniciateConnection(); db=new DataStorage(); return db; } //... } //here are the derivate classes with overriden méthods - static ones wont compile public class DataStorageMSA : DataStorage { protected static override bool IniciateConnection() { //compile error cn = new OleDbConnection(); cn.ConnectionString="Provider=..."; } protected override void IniciateInstanceObjects() { //create & ini dr,cmd,... dr = new OleDbDataReader(); cmd = new OleDbCommand(); } } public class DataStorageSQL : DataStorage { protected static override bool IniciateConnection() { //compile error cn = new SqlConnection(); cn.ConnectionString=""; } protected override void IniciateInstanceObjects() { //create & ini dr,cmd,... dr = new SqlDataReader(); cmd = new SqlCommand(); } } any help will be appreciated!...

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qazzwsxedcrfv21y ago
3) just got this one: :D class X{ static X() { int i=0; ...} //type constructor public X(int i) {...} //instance constructor }
shimtanny21y ago
Hi 1.) : this(...), respectivly : base(...) public class Test { // 1. ctor public Test(int i) : this(i, "default string") { } // 2. ctor public Test(int i, string s) { // Do something with i and s... } } -> Or 2. ctor calls 1. ctor, just swap the calls. 2.) Method default values. public void Test(int i) { // Do something with i... } // Method with default values public void Test() { public Test(6); // default value is 6. } 3.) no idea. 4.) no idea. I think this is not possible. Simon