Home » Tip Bank » Application Design » User Interface Design

Language: C
Expertise: Intermediate

Dec 29, 2003

Suppose you've got a user interface class with many user options that you need to set/get at the same time. Here's one way to implement this:

class CUI
{
public:
  CUI() : m_bOption(false), m_cOption('\0'), m_iOption(0), m_dOption(0.0)
{}
  //...
  void GetOptions(bool bOption, char cOption, int& riOption, double&
rdOption)
  {
    bOption = m_bOption;
    cOption = m_cOption;
    riOption = m_iOption;
    rdOption = m_dOption;
  }

  void SetOptions(bool bOption, char cOption, int const& riOption, double
const& rdOption)
  {
    m_bOption = bOption;
    m_cOption = cOption;
    m_iOption = riOption;
    m_dOption = rdOption;
  }

private:
  //...
  bool m_bOption;
  char m_cOption;
  int m_iOption;
  double m_dOption;
};

The problem with this implementation is that when the number of options increases, you need to transfer a larger amount of data as arguments to the getter/setter functions. This is not an efficient way to make use of the program's stack. The solution is to create an inner structure containing all the options:

#include <iostream>

using namespace std;

class CUI
{
public:
  struct SOptions
  {
    SOptions() : m_bOption(false), m_cOption('\0'), m_iOption(0),
m_dOption(0.0) {}
    bool m_bOption;
    char m_cOption;
    int m_iOption;
    double m_dOption;
  };

  CUI() {}
  //...
  void GetOptions(SOptions& roOptions)
  {
    roOptions.m_bOption = m_oOptions.m_bOption;
    roOptions.m_cOption = m_oOptions.m_cOption;
    roOptions.m_iOption = m_oOptions.m_iOption;
    roOptions.m_dOption = m_oOptions.m_dOption;
  }

  void SetOptions(SOptions const& roOptions)
  {
    m_oOptions.m_bOption = roOptions.m_bOption;
    m_oOptions.m_cOption = roOptions.m_cOption;
    m_oOptions.m_iOption = roOptions.m_iOption;
    m_oOptions.m_dOption = roOptions.m_dOption;
  }

private:
  //...
  SOptions m_oOptions;
};