Software development best practices & coding guidelines

Software Development Best Practices
----
Coding Standards & Maintainable Code
Ankur Goyal
Email: ankur.fbd@gmail.com

for(j=0; j<array_len; j+ =8)
{
total += array[j+0 ];
total += array[j+2 ]; /* Main body of
total += array[j+3]; * loop is unrolled
total += array[j+4]; * for greater speed.
total += array[j+5]; */
}
Warm up

for(j=0; j<array_len; j+ =8)
{
/*
Main body of loop is unrolled for greater speed
total += array[j+3];
*/
}
Isn’t it better ?

What is it you expect, to get out of this Session?
Participant’s Expectations

Setting Expectations Right
• What this session is about?
– Identify & appreciate the importance of Coding
Standards
– Few examples
– Introduction to standard supporting tools
• What this session is not about?
– Coding Tutorial
– Details on coding standards

Maintainability
• Maintainability is the ease with which a product
can be modified in order to:
– correct defects or their cause
– meet new requirements
– cope with a changed environment
– e.g. iOS 5 to iOS 6, windows 7 to windows 8
Write simple, self-documenting code that is pleasant to revisit
even after months.

Coding Standards
• Coding standards are guidelines for code style
and documentation.
• The purpose is that any developer familiar with
the guidelines can work on any code that
followed them.
• We need to write code that minimizes the time it
would take someone else to understand it ---
even if that someone else is you.

Why Have Coding Standards?
• Reducing the cost of
software maintenance is the
most often cited reason for
following coding standards.
• ~80% of the lifetime cost of
a piece of software goes to
maintenance.

Is this really necessary ?
• YES. To all programmers, even if there is only one
developer on the project.
• Because:
– Most of the time software is not maintained by
the original author.
– If everyone follows the standards, you feel
comfortable using your colleague's code,
because it seems like your own code.

hmmm really ?
– Estimations are approved considering an average
programmer who follows coding standards.
– Not following coding standards will lead to review
comments & thereby rework, which in turn will lead to
effort variation.
– Since most of the time client delivery dates are fixed
hence it all leads to extra hours spent in office -> more
time -> more money.
– It’s a vicious circle, only way out is following coding
standards.

Using constants on LHS
• Constants should always be used on left hand
side of equality operator
• Avoids invalid assignment
• Avoids null pointer exceptions

Using constants on LHS
T h i s c o d e c a n c a u s e
N u l l P o i n t e r E x c e p t i o n
i f p a s s e d a r g u m e n t
‘ i n p u t ’ i s n u l l
R i g h t A p p r o a c h

Indentation
• Gives an indication of scope though doesn’t
affect program
• Must for maintainability & readability of code

Example
Compare
- Easier to Read
- Easier to Understand
- Easier to maintain
To
Pressing “Ctrl+shift+f” in eclipse formats source file
(set up your formatting style in Window|preferences | java | code style | formatter)

Commenting Code
• Document WHY & WHAT along with HOW.
• Comments should
- Clearly demonstrate the function of the code,
both to yourself and to other developers
• Comments should NOT be
- Too long
- Overcomplicated

Example
To
 Comments are not about how much you write
 Comments should add illustration to the code for maintainability

Naming Variables
• Variable names are often thought to be less
important but they are vital to understanding
certain pieces of code.
• In the majority of programming languages,
variables can be assigned almost any name.

Example
Compare following:
To:
Trade off is generally between meaningfulness & shortness, rule of thumb is, always give
priority to meaningfulness.

Instance Creation
• Do not create instances as far as possible.
• creation of new instance is avoided in the
internal part of loop.

Example
Compare
Instance creation in loop, this may lead
to out of memory error…
To

Instance Creation
• Use valueOf() instead of new().
• valueOf() provides value from cache while
new() creates new instance.

Cast
• As much as possible cast must be enclosed in
condition statement of instanceof.
Use instanceof()
This may lead to classcastexception
Use instanceof to avoid
classcastexception

Unreadable Code
• Write a code that can be understood by any
average programmer.
• This helps in maintainability & readability of
code.
• Helpful in understanding time critical projects

Example
Compare
To
Programmer’s expertise is not in writing complex code, expertise
is to write a code which is easy to understand & maintain.

String Concatenation
• Use StringBuffer and StringBuilder for String
concatenation operations.
• String is immutable hence creates new objects
whenever the value is changed
• Use StringBuffer if application is multithreaded &
synchronization is required
• Use StringBuilder elsewhere.

Example
Instead of
Use
Or
String object is
immutable whereas
StringBuffer/
StringBuilder
objects are mutable

REPOSITORY COMMENTS
• Often it is observed that repository comments do
not get the attention they deserve.
• Repository comments should convey the changes
committed along with applicable references e.g
– If bug is fixed mention fixed bug ID
– If any CR is implemented mention CR number/name
– If review comments are fixed mention review plan id

Example
Following are some of the real svn repo comments:
SVN repo comments serve purpose of maintaining code revision history, pay
respect to this fact & spend some time to write useful comments

Coding Standard & Best Practices
Tools
• CheckStyle
– makes sure that everyone in the team write code in a
similar manner
– is the glue that enables people to work together and to
free up their creativity instead of spending time and
energy at understanding inconsistent code.
• PMD
– reminds you of bad practices such as:
• Catching an exception without doing anything
• Suboptimal code - wasteful String/StringBuffer usage
• Duplicate code - copied/pasted code means copied/pasted bugs

Recap
• The purpose is that any developer familiar with the
guidelines can work on any code that followed them.
• Following coding standards saves both time and
money.
• Standardize early - the effort to bring your old work
into the standard will be too great otherwise.
• Document every time you violate a standard.
• Industry Standards > organizational standards >
project standards > no standards.

THANKS !!!
 Guidelines & practices mentioned in this slide were just a
tip of iceberg, there is no hard & fast rule regarding
guideline & they generally differ on basis of domain,
technology used & clients’ requirement etc.
Purpose of this presentation was to encourage habit of
following standards by identifying importance of the same.
Finally, following guidelines & adhering to standards is
responsibility of each individual.
Conclusion

Software development best practices & coding guidelines

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