This document is created with the unregistered version of CHM2PDF Pilot in Software

Print QR Code 2d barcode in Software This document is created with the unregistered version of CHM2PDF Pilot
This document is created with the unregistered version of CHM2PDF Pilot
Denso QR Bar Code Creator In C#
Using Barcode maker for VS .NET Control to generate, create Denso QR Bar Code image in .NET framework applications.
144 An improvement on controllable handles
QR Code Encoder In .NET
Using Barcode encoder for ASP.NET Control to generate, create QR Code JIS X 0510 image in ASP.NET applications.
Useful as our controllable handle might be, it doesn't quite do all we want For example, suppose we want to use it to reimplement the Str class from 12 As we saw in 1234/219, we implicitly copy a lot of characters to form the new Strs that result from concatenating two existing Str objects By reference-counting the Str class, we might think that we can avoid at least some of these copies:
QR Code 2d Barcode Encoder In .NET Framework
Using Barcode maker for VS .NET Control to generate, create QR image in VS .NET applications.
// does this version work class Str { friend std::istream& operator>>(std::istream&, Str&); public: Str& operator+=(const Str& s) { datamake_unique(); std::copy(sdata->begin(), sdata->end(), std::back_inserter(*data)); return *this; } // interface as before typedef Vec<char>::size_type size_type; // reimplement constructors to create Ptrs Str(): data(new Vec<char>) { } Str(const char* cp): data(new Vec<char>) { std::copy(cp, cp + std::strlen(cp), std::back_inserter(*data)); } Str(size_type n, char c): data(new Vec<char>(n, c)) { } template<class In> Str(In i, In j): data(new Vec<char>) { std::copy(i, j, std::back_inserter(*data)); } // call make_unique as necessary char& operator[](size_type i) { datamake_unique(); return (*data)[i]; } const char& operator[](size_type i) const { return (*data)[i]; } size_type size() const { return data->size(); } private: // store a Ptr to a vector Ptr< Vec<char> > data; }; // as implemented in 1232/216 and 1233/219 std::ostream& operator<<(std::ostream&, const Str&); Str operator+(const Str&, const Str&);
Printing Denso QR Bar Code In Visual Basic .NET
Using Barcode generator for .NET framework Control to generate, create QR Code image in Visual Studio .NET applications.
We have preserved the interface to Str, but we have fundamentally changed the implementation Instead of holding a vector directly in each Str object, we store a Ptr to the vector This design allows multiple Strs to share the same underlying character data The constructors initialize this Ptr by allocating a new vector initialized with the appropriate values The code for the operations that read, but do not change, data are unchanged from our previous version Of course, these operations now operate on a Ptr, so there is an indirection through the pointer stored in the Ptr to get at the underlying characters that make up the Str The interesting operations are the ones that change the Str, such as the input operator, the compound concatenation operator, and the nonconst version of the subscript operator For example, look at the implementation of Str::operator+= It wants to append data to the underlying vector, so it
Barcode Drawer In VB.NET
Using Barcode drawer for Visual Studio .NET Control to generate, create barcode image in VS .NET applications.
This document is created with the unregistered version of CHM2PDF Pilot
Creating Code-128 In C#.NET
Using Barcode generation for .NET framework Control to generate, create Code 128 Code Set B image in Visual Studio .NET applications.
calls datamake_unique() Once it has done so, the Str object has its own copy of the underlying data, which it can modify freely
Creating Code 128A In Java
Using Barcode encoder for Java Control to generate, create Code 128 Code Set B image in Java applications.
1441 Copying types that we can't control
Reading EAN13 In .NET Framework
Using Barcode scanner for .NET Control to read, scan read, scan image in Visual Studio .NET applications.
Unfortunately, the definition of make_unique has a serious problem:
Drawing Bar Code In Java
Using Barcode generation for Java Control to generate, create barcode image in Java applications.
template<class T> void Ptr<T>::make_unique() { if (*refptr != 1) { --*refptr; refptr = new size_t(1); p = p p->clone() : 0; } }
Paint GS1-128 In VS .NET
Using Barcode maker for ASP.NET Control to generate, create UCC.EAN - 128 image in ASP.NET applications.
// here is the problem
Make DataMatrix In Java
Using Barcode encoder for Java Control to generate, create ECC200 image in Java applications.
Look at the call to p->clone Because we are using a Ptr< vector<char> >, this call will try to call the clone function that is a member of vector<char> Unfortunately, no such function exists! Yet the clone function has to be a member of the class to which we are attaching a Ptr, because only in that way can it be a virtual function In other words, making clone a member is critically important to making it possible for Ptr to work across all members of an inheritance hierarchy; yet doing so is impossible, because we can't change the definition of the Vec class That class is designed to implement a subset of the interface to the standard vector class If we add a clone member, we'll no longer have a subset because we'll have added a member that vector does not have What can we do Solutions to tough problems such as this one often involve what we jokingly call the fundamental theorem of software engineering: All problems can be solved by introducing an extra level of indirection The problem is that we are trying to call a member function that does not exist, and we have no way to cause the member function to exist The solution, then, is not to call the member function directly but to define an intermediary global function that we can both call and create We will still call this new function clone
ANSI/AIM Code 39 Creator In VS .NET
Using Barcode drawer for .NET framework Control to generate, create Code 39 Full ASCII image in Visual Studio .NET applications.
template<class T> T* clone(const T* tp) { return tp->clone(); }
Print GS1 - 13 In .NET Framework
Using Barcode drawer for .NET Control to generate, create EAN13 image in .NET applications.
Generate Barcode In Java
Using Barcode generation for Java Control to generate, create bar code image in Java applications.
ANSI/AIM Code 39 Generation In .NET Framework
Using Barcode creation for ASP.NET Control to generate, create Code-39 image in ASP.NET applications.
GTIN - 13 Creation In .NET Framework
Using Barcode encoder for ASP.NET Control to generate, create GTIN - 13 image in ASP.NET applications.
Decode Data Matrix ECC200 In VS .NET
Using Barcode scanner for VS .NET Control to read, scan read, scan image in VS .NET applications.