Visitor pattern allows us to change the class structure with out changing the actual class. Its way of separating the logic and algorithm from the current data structure. Due to this you can add new logic to the current data structure with out altering the structure. Second you can alter… Continue reading
Strategy pattern are algorithms inside a class which can be interchanged depending on the class used. This pattern is useful when you want to decide on runtime which algorithm to be used. Let’s try to see an example of how strategy pattern works practically. Let’s take an example of a… Continue reading
State pattern allows an object to change its behavior depending on the current values of the object. Consider the figure ‘State pattern example’. It’s an example of a bulb operation. If the state of the bulb is off and you press the switch the bulb will turn off. If the… Continue reading
Observer pattern helps us to communicate between parent class and its associated or dependent classes. There are two important concepts in observer pattern ‘Subject’ and ‘Observers’. The subject sends notifications while observers receive notifications if they are registered with the subject. Below figure ‘Subject and observers’ shows how the application… Continue reading
Memento pattern is the way to capture objects internal state with out violating encapsulation. Memento pattern helps us to store a snapshot which can be reverted at any moment of time by the object. Let’s understand what it means in practical sense. Consider figure ‘Memento practical example’, it shows a… Continue reading
Many a times in projects communication between components are complex. Due to this the logic between the components becomes very complex. Mediator pattern helps the objects to communicate in a disassociated manner, which leads to minimizing complexity. Figure: – Mediator sample example Let’s consider the figure ‘Mediator sample example’ which… Continue reading
Iterator pattern allows sequential access of elements with out exposing the inside code. Let’s understand what it means. Let’s say you have a collection of records which you want to browse sequentially and also maintain the current place which recordset is browsed, then the answer is iterator pattern. It’s the… Continue reading
Interpreter pattern allows us to interpret grammar in to code solutions. Ok, what does that mean?. Grammars are mapped to classes to arrive to a solution. For instance 7 – 2 can be mapped to ‘clsMinus’ class. In one line interpreter pattern gives us the solution of how to write… Continue reading
Command pattern allows a request to exist as an object. Ok let’s understand what it means. Consider the figure ‘Menu and Commands’ we have different actions depending on which menu is clicked. So depending on which menu is clicked we have passed a string which will have the action text… Continue reading
There are situations in project where we want only one instance of the object to be created and shared between the clients. For instance let’s say we have the below two classes, currency and country.These classes load master data which will be referred again and again in project. We would… Continue reading