How to allocate a C++ Object in Gsoap

Question

I have a soap response structure that contains an optional error parameter (I've abbreviated these hopefully it hasn't created syntax errors). Both classes are generated by gsoap.

Response Object

class SOAP_CMAC ns1__LoginResponse : public ns1__Response
{
public:
    class ns1__Error *Error;    /* optional element of type ns1:Error */
    int *SessionID; /* SOAP 1.2 RPC return element (when namespace qualified) */    /* optional element of type xsd:int */
public:
    virtual int soap_type() const { return 127; } /* = unique type id SOAP_TYPE_ns1__LoginResponse */
    virtual void soap_default(struct soap*);
    virtual void soap_serialize(struct soap*) const;
    virtual int soap_put(struct soap*, const char*, const char*) const;
    virtual int soap_out(struct soap*, const char*, int, const char*) const;
    virtual void *soap_get(struct soap*, const char*, const char*);
    virtual void *soap_in(struct soap*, const char*, const char*);
             ns1__LoginResponse() { ns1__LoginResponse::soap_default(NULL); }
    virtual ~ns1__LoginResponse() { }
};

Error Object

class SOAP_CMAC ns1__Error : public xsd__anyType
{
public:
    std::string *Code;  /* optional element of type xsd:string */
    std::string *Description;   /* optional element of type xsd:string */
public:
    virtual int soap_type() const { return 100; } /* = unique type id SOAP_TYPE_ns1__Error */
    virtual void soap_default(struct soap*);
    virtual void soap_serialize(struct soap*) const;
    virtual int soap_put(struct soap*, const char*, const char*) const;
    virtual int soap_out(struct soap*, const char*, int, const char*) const;
    virtual void *soap_get(struct soap*, const char*, const char*);
    virtual void *soap_in(struct soap*, const char*, const char*);
             ns1__Error() { ns1__Error::soap_default(NULL); }
    virtual ~ns1__Error() { }
};

When I detect an error in my service I have to allocate this ns1__Error object.

I have tried using soap_malloc

ns1__Error* err = (ns1__Error*)soap_malloc(soap_context, sizeof(ns1__Error));

but I have realised this is fatally flawed. When gsoap later calls one of the objects methods, it crashes. The objects constructor has not been called.

If I call soap_malloc then use a placement new to call the constructor then it works but I have no place to call the destructor.

void* errmem = soap_malloc(soap_context, sizeof(ns1__Error));
ns1__Error err= new (errmem) ns1__Error();

This does not crash but feels wrong, especially as gsoap made me the class and made it so I have to allocate it myself, yet doesn't seem to give me a mechanism to do just that. It will also leave my object in a potentially wrong state at deallocation time, as the destructor has not been called.

There is (admittedly dated) talk of a soap_new_Class function, but I do not see this in version 2.8.18.

How can I make this allocation, so that the object is allocated, constructed and destructed properly and gsoap can clean it up once it has finished with it?

Answer 1

Gsoap defines an allocation function for every type it creates from your wsdl or header file.

For a type X it will define a function similar to

X* soap_new_X(struct soap* s, int num = -1);

EDIT: It would seem in the question I misunderstood soap_new_Class as meaning a literal function name.

Which returns a num length array of allocated object of type X (seems -1 is a special case which means just allocate a single object). This is included in gsoaps internal registry of objects to be deallocated when you make a call to soap_destroy , after your request has been served.

For my error object it looks like.

inline ns1__Error * soap_new_ns1__Error(struct soap *soap, int n = -1);

There is a second function created

ns1__Error * soap_new_req_ns1__Error(struct soap *soap, int mandatory_param);

This will allocate the object but also allows setting of any mandatory parameters.

These functions prototypes are defined in SoapH.h. I think the name of the file will change depending on the parameters you pass when you generate your code.

To allocate a std::string, which is common in gsoap (or at least my use thereof) there is the function.

inline std::string * soap_new_std__string(struct soap *soap, int n = -1);