1. High-Quality Routines
Chapter 7

3. What is a “routine?”
A routine is an individual method or procedure achieves a single purpose. Examples include a function in C++, a method in Java, a function or sub procedure in Visual Basic.
The routine makes programs easier to read and easier to understand.
It is also used for saving space and improving performance

4. Valid Reasons to Create a Routine
Reduce complexity
Make a section of code readable
Avoid duplicate code
Hide pointer operations
Improve portability
Improve performance

5. Cohesion
have each routine do one thing well and not do anything else. (High Cohesion)
Examples of highly cohesive routines include sin(), GetCustomerName(), EraseFile(), CalculateLoanPayment(), and AgeFromBirthday().
Example of low cohesive routine is TanAndCosine()
One study of 450 routines found that 50 percent of the highly cohesive routines were fault free.
To increase cohesion, split the operations into individual routines.

6. Good Routine Names .. Guidlines
Describe everything the routine does
Avoid meaningless or wishy-washy verbs:
Routine names like HandleCalculation(), PerformServices(), ProcessInput(), and DealWithOutput() don’t tell you what the routines do.
HandleOutput() could be replaced with FormatAndPrintOutput()
Make names of routines as long as necessary
To name a function, use a description of the return value
If a function returns a value, the function should be named for the value it returns. For example, cos(), customerId.Next(), printer.IsReady(), and pen.CurrentColor() are all good function names that indicate precisely what the functions return

7. Good Routine Names .. Guidlines
Use opposites precisely
Examples
add/remove
begin/end
create/destroy
first/last
get/put
get/set
increment/decrement
insert/delete
lock/unlock
min/max
next/previous

8. How Long Can a Routine Be?
IBM once limited routines to 50 lines
TRW limited them to two pages
In worst case, number of lines in one routine should not exceed 200 lines

9. How to Use Routine Parameters
Interfaces between routines are some of the most error-prone areas of a program.
Put parameters in input-modify-output order
If several routines use similar parameters, put the similar parameters in a consistent order
Use all the parameters