Designing Traditional Components

Designing Traditional Components

• Introduction : Traditional components are designed based on different constructs like 
• Sequence,
• Condition, 
• Repetition. 
• Sequence implements processing steps that are essential in the specification of any algorithm. 
• Condition provides the facility for selected processing based on some logical occurrence. 
• Repetition allows for looping. 
• These three constructs are fundamental to structured programming— an important component-level design technique.
• The use of the structured constructs reduces program complexity and thereby enhances readability, testability, and maintainability. 
• The use of a limited number of logical constructs also contributes to a human understanding process that psychologists call chunking.
• Graphical Design Notation 
• A picture is worth a thousand words,” but it’s rather important to know which picture and which 1000 words. 
• There is no question that graphical tools, such as the UML activity diagram or the flowchart, provide useful pictorial patterns that readily depict procedural detail. 
• The activity diagram allows you to represent sequence, condition, and repetition— all elements of structured programming. 
• It is a descendent of an earlier pictorial design representation (still used widely) called a flowchart. 
• A flowchart, like an activity diagram, is quite simple pictorially. A box is used to indicate a processing step. A diamond represents a logical condition, and arrows show the flow of control

• Tabular Design Notation 
• In many software applications, a module may be required to evaluate a complex combination of conditions and select appropriate actions based on these conditions.
• Decision tables provide a notation that translates actions and conditions into a tabular form. 
• The table is difficult to misinterpret and may even be used as a machine-readable input to a table-driven algorithm.

• Program Design Language 
• Program design language (PDL), also called structured English or pseudocode, 
• It incorporates the logical structure of a programming language with the free-form expressive ability of a natural language (e.g., English). 
• Narrative text (e.g., English) is embedded within a programming language-like syntax. 
• Automated tools can be used to enhance the application of PDL.
• A basic PDL syntax should include constructs for 
• Component definition, 
• Interface description, 
• Data declaration, 
• Block structuring, 
• Condition constructs, 
• Repetition constructs, 
• Input-output (I/O) constructs. 
• It should be noted that PDL can be extended to include keywords.