Implementing Interfaces

[knudmt]

Hi there, total C++ newb.

so I have a header file that is set up like so:

namespace whatever{
  
   classA
   {
      public:
          virtual void classAMethod();
   }

   classB
   {
      public:
           virtual void classBMethod();
   }

   classC
   {
      public:
            classC(classA* arg1, classB* arg2);
            virtual void classCMethod();
      private:
            classB* classBvariable;
            classA* classAVariable
   }
}

I have a cpp file that implemented this garbage

namespace whatever{

   classC::classC(classA* arg1, classB* arg2) : arg1(arg1), arg2(arg2)
   {

   }

   classB* classB::classBMethod()
   {
       NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
                    
                    request = (NSMutableURLRequest)classAVariable; // problem here. compiler error: use of undeclared identifier 'classAVariable'

   }
}

There are some other methods that are not shown here. But the idea is that I have a method that creates a HTTP Request and returns pointer to classAVariable
Then classAVariable is used by another method to complete the Web Request. I know that some of this is abstract and convoluted. but I inherited these interfaces, not really happy about the set up.

So really the classAVariable is a global variable that I would like to share throughout classA, classB, and classC.

Normally my domain is C#. Can someone please point out the error in my ways!

[Zhuge]

Couldn't you pass the classAVariable to the method then? It seems strange to me that you would have several classes that interoperate on a global variable to work properly.

[knudmt]

Hi Zhuge thanks for the reply.

you simply mean:

classB* classB::classBMethod(classA* classAVariable)
{
// do some work :)
}

I thought about that. I'm pretty sure that would work. Is that the best way to implement this? Just curious, pretty much anyone here has more exp than myself in C++

[Zhuge]

Without knowing why you need this variable I can't really give you any more details. Like I said before, it seems odd to have a member that all the classes need in order to work. If, from the method's perspective, its just some random data, then there should be no issue in terms of good/bad practice.

[knudmt]

hopefully this will shed some light

// the https response
                class HttpsResponse
                {
                public:
                    virtual std::string getHeaderValue(std::string key);
                    virtual std::string getContentAsString();
                };
                // base class for httpsRequest
                class HttpsRequest
                {
                public:
                    virtual void setHeaderValue(std::string key, std::string value);
                    virtual HttpsResponse* submit(); //caller takes ownership of result
                };
                // post request inherits from https request
                class HttpsPostRequest : public HttpsRequest
                {
                public:
                    virtual Uploader* UploadStream(); //caller takes ownership of result
                };
                
                class WebCommunication
                {
                public:
                    WebCommunication(HttpsRequest* request, HttpsPostRequest* postRequest);
                    virtual HttpsPostRequest* makeHttpsPostRequest(std::string uri); //caller takes ownership of result
                    virtual HttpsRequest* makeHttpsGetRequest(std::string uri); //caller takes ownership of result
                private:
                    AppleHttpsRequest *appleRequest; // not sure I need these
                    AppleHttpsPostRequest *applePostRequest; // not sure I need these
                };

the .cpp

WebCommunication::WebCommunication(HttpsRequest* request, HttpsPostRequest* postRequest)
                :request(request), 
                PostRequest(postRequest)
                {
                    
                }
                                
                std::string HttpsResponse::getHeaderValue(std::string key)
                {
                    
                    
                }
                
                std::string HttpsResponse::getContentAsString()
                {
                    
                }
                
                void HttpsRequest::setHeaderValue(std::string key, std::string value)
                {
                    
                }
                
                
                
                
                // this just creates an HttpsPostRequest
                HttpsPostRequest* WebCommunication::makeHttpsPostRequest(std::string uri)
                {
                    NSString *urlString = [NSString stringWithFormat:@"%@", uri.c_str()];
                    NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
                    [request setURL:[NSURL URLWithString:urlString]];
                    [request setHTTPMethod:@"POST"];
                    
                    // should set the headers
                    NSString *contentType = [NSString stringWithFormat:@"text/xml"];
                    [request addValue:contentType forHTTPHeaderField:@"Content-Type"];
                    
                    //create the body - will the body be just raw bytes?
                    NSMutableData *postBody = [NSMutableData data];
                    [postBody appendData:[[NSString stringWithFormat:@"<xml>"] dataUsingEncoding:NSUTF8StringEncoding]];
                    [postBody appendData:[[NSString stringWithFormat:@"<yourcode/>"] dataUsingEncoding:NSUTF8StringEncoding]];
                    [postBody appendData:[[NSString stringWithFormat:@"</xml>"] dataUsingEncoding:NSUTF8StringEncoding]];
                    
                    [request setHTTPBody:postBody];
                    
                    postRequest = (HttpsPostRequest*)request;
                    return postRequest;
                }
                
                // Creates Https Get Request
                HttpsRequest* WebCommunication::makeHttpsGetRequest(std::string uri)
                {
                    NSString *urlString = [NSString stringWithFormat:@"%@", uri.c_str()];
                    NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
                    [request setURL:[NSURL URLWithString:urlString]];
                    [request setHTTPMethod:@"GET"];
                    
                    // should set the headers
                    NSString *contentType = [NSString stringWithFormat:@"text/xml"];
                    [request addValue:contentType forHTTPHeaderField:@"Content-Type"];
                    
                    //create the body - will the body be just raw bytes?
                    NSMutableData *postBody = [NSMutableData data];
                    [postBody appendData:[[NSString stringWithFormat:@"<xml>"] dataUsingEncoding:NSUTF8StringEncoding]];
                    [postBody appendData:[[NSString stringWithFormat:@"<yourcode/>"] dataUsingEncoding:NSUTF8StringEncoding]];
                    [postBody appendData:[[NSString stringWithFormat:@"</xml>"] dataUsingEncoding:NSUTF8StringEncoding]];
                    
                    [request setHTTPBody:postBody];
                    
                    //HttpsPostRequest *request = (HttpsPostRequest*)request;
                    request = (HttpsRequest*)request;
                    
                    return appleRequest;

                }
                
                // this would simply submit the request and return the response data
                HttpsResponse* HttpsRequest::submit()
                {
                    
                    NSMutableURLRequest *request = [[[NSMutableURLRequest alloc] init] autorelease];
                    
                    request = (NSMutableURLRequest)request;
                    
                    
                    NSHTTPURLResponse* urlResponse = nil;  
                    NSError *error = [[NSError alloc] init];  
                    NSData *responseData = [NSURLConnection sendSynchronousRequest:request returningResponse:&urlResponse error:&error];  
                    NSString *result = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
                    
                    NSLog(@"Response Code: %d", [urlResponse statusCode]);
                    if ([urlResponse statusCode] >= 200 && [urlResponse statusCode] < 300) {
                        NSLog(@"Response: %@", result);
                    }
                    //here you get the response    
                    
                    // wrap the raw response in AppleHttpsResponse not sure why
                    HttpsResponse *response_data = (HttpsResponse*)urlResponse;
                    
                    return response_data; // will have to cast this back to HttsResponse
                }

I have been looking at this for a few hours. Maybe I'm just implementing this completely incorrectly