Geek Answers Handbook

Code Complete 2nd, Composition and Delegation

After several weeks read on this forum, I thought it was time for me to make my first post.

I am currently re-reading Code Complete. I think it’s been 15 years since the last time, and I found that I still can’t write the code ;-)

In any case, on page 138 in Code Complete you will find this coding horror example. (I deleted a piece of code)

class Emplyee {
public: 
 FullName GetName() const;
 Address GetAddress() const;
 PhoneNumber GetWorkPhone() const;
 ...

 bool IsZipCodeValid( Address address);
 ...

private: 
   ...
}

What Steve considers bad is that the functions are not related to each other. Or he writes: “There is no logical connection between employees and routines that check zip codes, phone numbers, or job classifications”

Well, I totally agree with him. Maybe something like the example below is better.

class ZipCode
{
public:
 bool IsValid() const;
    ...
}

class Address {
public:
   ZipCode GetZipCode() const;
   ...
}

class Employee {
public: 
 Address GetAddress() const;
    ...
}

, zip , - .

employee.GetAddress().GetZipCode().IsValid();

.

, , -, .

class ZipCode
{
public:
 bool IsValid();
}

class Address {
public:
   ZipCode GetZipCode() const;
   bool IsZipCodeValid() {return GetZipCode()->IsValid());
}

class Employee {
public: 
 FullName GetName() const;
 Address GetAddress() const;
 bool IsZipCodeValid() {return GetAddress()->IsZipCodeValid());
 PhoneNumber GetWorkPhone() const;
}

employee.IsZipCodeValid();

, .

, . - , ?

+5
3

.

( ), , employee.IsZipCodeValid() . IsZipCodeValid,

employee.GetAddress().GetZipCode().IsValid();
, , , , .

.;)

+1

:

class ZipCode
{
public:
 bool IsValid();
}

class Address {
public:
   ZipCode GetZipCode() const;
   bool IsAddressValid();
   bool IsValid() {return GetZipCode()->IsValid() && IsAddressValid());
}

class Employee {
public: 
 FullName GetName() const;
 Address GetAddress() const;
 bool IsEmployeeValid();
 bool IsValid() {return GetAddress()->IseValid() && IsEmployeeValid());
 PhoneNumber GetWorkPhone() const;
}

employee.IsValid();
+7

Employee , Zip Address, . Address .

class Address
{
    public:
        static IsZipValid(ZipCode zip) { return zip.isValid(); }
};


Address::IsZipValid(employee.GetAddress().GetZipCode());

, .

0

More articles:


All Articles