design - Volatile polymorphism (?) in gnu C++ -

-

i have raw binary dump of assembler split blocks (code, data, ignored, images etc). have walker increments position via virtual ++ operator. if it's in data block, moves 32 bytes, code number of bytes in instruction, ignored moves size of block etc. when reaches end of block, needs "transform" walker type of next block while keeping data, data pointer, block lookup etc.

there ways using switch statements, array of objects pointing same base etc wondering if there's better way? somehow transform derived object different object same physical base class?

can transform derived object different derived object same physical base class?

no, far less of issue you'd expect. if have derived1 first; on stack, makes no sense try change first derived2. however, there's no real polymorphism happening. polymorphism works magic when have base* second; points @ derived object. , 99% of time, that's going allocated on heap. can create new derived2 copies shared data *second, , make second point @ new derived2, , delete original pointee. obviously, use smart pointers.

so, apply this, "walker" class (which should iterator, think), contain std::unique_ptr<implementationbase> impl; points thing tells how advance.

however, virtual indirection comes @ performance penalty, , requires heap allocation unless confusing tricks. it's slower switch, takes more memory switch, takes more code switch, it's more confusing switch.... use switch.


Comments

Post a Comment

Popular posts from this blog

c++ - No viable overloaded operator for references a map -

-
i trying use map can make tag names reference number. when try , use it, in code error (6 in total every time reference map): src/main.cpp:25:45: error: no viable overloaded operator[] type 'std::map<std::string, std::string>' const char* idcs = node.child_value(tagmap[3]); this code: #include "pugi/pugixml.hpp" #include <iostream> #include <string> #include <map> int main() { pugi::xml_document doca, docb; std::map<std::string, pugi::xml_node> mapa, mapb; std::map<std::string, std::string> tagmap {{"1", "data"}, {"2", "entry"}, {"3", "id"}, {"4", "content"}}; if (!doca.load_file("a.xml") || !docb.load_file("b.xml")) { std::cout << "can't find input files"; return 1; } (auto& node: doca.child(tagmap[1]).children(tagmap[2])) { co
Read more

java - Custom OutputStreamAppender not run: LOGBACK: No context given for <MYAPPENDER> -

-
i wish write custom appender on basis of outputstreamappender . wrote following class package tests; import java.io.ioexception; import java.io.outputstream; import ch.qos.logback.core.outputstreamappender; public class myappender<e> extends outputstreamappender<e> { public myappender() { system.out.println("myappender created"); setoutputstream(new outputstream() { @override public void write(int b) throws ioexception { throw new unsupportedoperationexception(); } }); } } then wrote following runner: package tests; import org.slf4j.loggerfactory; import ch.qos.logback.classic.logger; public class runner { private static final logger log = (logger) loggerfactory.getlogger(runner.class); public static void main(string[] args) { //log.addappender(new myappender<iloggingevent>()); log.info("hello world"); } } finall
Read more

java - Cannot secure connection using TLS -

-
i'm trying establish secure socket connection between java client applet (built jdk 1.7.0_75-b13) , vc++ server application. as test vehicle, used vc++ client/server sample found in msdn forums, modified use schannel , able establish socket using cipher suite tls_rsa_with_aes_128_cbc_sha. works of tls 1.0/1.1/1.2. when try opening socket java applet same server application, connection rejected server reporting following: tls 1.0 acceptsecuritycontext failed: 0x80090327 tls 1.1 acceptsecuritycontext failed: 0x80090331 tls 1.2 acceptsecuritycontext failed: 0x80090331 this java code used create socket: debugprint("setting secure connection"); sslsocketfactory sslsocketfactory = (sslsocketfactory) sslsocketfactory.getdefault(); sslsocket sslsocket = (sslsocket) sslsocketfactory.createsocket("127.0.0.1", socketnumber); debugprint("starting handshake"); sslsocket.settcpnodelay(true); sslsocket.setsolinger(false, 0); sslsocket.s
Read more