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vectorX*::insert() returning X** const

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Started by nlbs November 14, 2008 12:38 PM

4 comments, last by nlbs 15 years, 5 months ago

nlbs

100

Author

November 14, 2008 12:38 PM


typedef std::map<string, Js::JType*> ElemMap;
ElemMap list;
vector<Js::JType*> clones;
.....
ElemMap::iterator appendClone(const string& key, Js::JType* heapObj){
  return list.insert(make_pair(key, &(*clones.insert(clones.end(), heapObj)) )).first;//Error here in this line
}

The above mentioned line is firing the following error

jobject.h:89: instantiated from here
/usr/include/c++/4.3/bits/stl_pair.h:106: error: cannot convert 'Js::JType** const' to 'Js::JType*' in initialization

I am also including that line of stl_pair.h which means

&(*clones.insert(clones.end(), heapObj))

is returning Js::JType** const Instead of Js::JType*

      template<class _U1, class _U2>
        pair(const pair<_U1, _U2>& __p)
	: first(__p.first),
	  second(__p.second) { }//106

Here is the code for Js::JType::clone()

virtual Js::JType* clone() const {return new Js::JType(*this);}

Sneftel

1,788

November 14, 2008 12:49 PM

Blegggh. That is one ugly-ass line of code. Break it into a few lines for readability's sake. FWIW, though, your problem is that you're explicitly finding the address of the just-inserted vector item, despite the fact that what you probably actually want is the item (a pointer) itself.

nlbs

100

Author

November 14, 2008 09:29 PM

If I break it into some line it would be:

ElemMap::iterator appendClone(const string& key, Js::JType* heapObj){  Js::JType* __tmp = &(*clones.insert(clones.end(), heapObj));  return list.insert(make_pair(key, __tmp )).first;//Error here in this line}

Now how to solve it.

clones.insert(clones.end(), heapObj)

returns an iterator which is dereferenced by * operator and I am again getting the Js::JType* by referencing it. should I call operator->() Instead of doing it in this way ??

Antheus

2,410

November 14, 2008 09:37 PM

ElemMap::iterator appendClone(const string& key, Js::JType* heapObj){  clones.push_back(heapObj);  return list.insert(make_pair(key, heapObj));}

nlbs

100

Author

November 14, 2008 10:00 PM

I think you meant to say return list.insert(make_pair(key, heapObj)).first;
Ya that works . actually I was trying to write terse code in one line. However why my insert() Code is not working ??
according to the manual (If I've not misunderstood something) it should not become const.

nlbs

100

Author

November 14, 2008 10:42 PM

It has been fixed as I am storing Object pointers I need to use

return list.insert(make_pair(key, (*clones.insert(clones.end(), heapObj)) )).first;

It was being double referenced.

vectorX*::insert() returning X** const

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