thetaoofpg.txt

编程之道 为你解释编程的真谛！！！

The Tao of Programming

Frontispiece

Ancient likeness of the ninth immortal of computer programming.  He is shown with the traditional lotus(which symbolizes project planning), crane(assembly code), jackal(job control language), and floppy disk(file management system).  He is suspended between earth and sky, meditating on the contents of the cosmic Q-Register.  Above him are pictured flitting bats, which represent the distractions of the material world.  Below him, the primordial dragon of chaos gives birth to the mystery of Tao.

Preface

The field of compuarcheology is sufficiently new that even an amateur like myself can sometimes stumble upon significant discoveries.  Several years ago, as I was making a somewhat desultory search through a pile of obsolete punch cards, I discovered what appeared to be a set of coded bit-map images.  The images were sandwiched among thousands of obsolete RPG programs and I wouldn't have given them a second glance if it hadn't been for a hand-written note on one of the cards saying: "Destroy after processing."

This quite naturally piqued my interest and I was determined to discover the contents of the mysterious card pack.  It was clear from the first that the images had been scrambled and encrypted, but with perseverance(as well as hundreds of hours of raw CPU time), I was finally able to produce a rough outline of the first image, which is reproduced at the beginning of Book One.

But the decryption of the images turned out to be the simplest part of the project.  The manuscript was in an unfamiliar dialect and had to be transcribed before any realistic translation could be attempted.  As this effort proceeded, it became clear to me that I was dealing not with a simple set of test images(as I had originally believed), but the legendary "Tao of Programming" itself.

It is difficult to describe my excitement at this revelation.  Though I had certainly heard of the "Tao of Programming", I had never seen a copy of the work nor met anybody who possessed one.  I had heard many times about how the "Tao of Programming" had a profound, if covert, effect upon the early development of computers.  According to these legends, the "Tao of Programming" represented the first attempt to treat the art of programming as an organic whole.  As such it was violently opposed by both the academic and business communities, who viewed it as a threat to the established order of things.  The "Tao of Programming" was forced underground, circulating among select programmers and then only after rigorous initiations.

Eventually, this so-called "Integration Sect" became so powerful that it could no longer remain clandestine.  The persecutions that followed(often referred to as "The Great Lay-Off") resulted not only in the destruction of the sect but (it was assumed) the loss of the esoteric literature that comprised the sect's inner teachings.
The truth in these legends is impossible to verify and thus should be discounted as mere colorful tales, more the province of the anthropologist than the serious compuarcheologist.  But now that a manuscript has finally surfaced, it may be possible to separate the truth from the myth.

The origins of the "Tao of Programming" are lost in the mists of time.  From internal references we know that certain passages can be dated from after the invention of the integrated circuit.  But more accurate placing of the work will have to wait until the full force of scholarship has been turned upon this hiterto-unknown classic.

The authorship of the "Tao of Programming" also remains a mystery.  Tradition assigns certain portions of the text to Yong Yo Sef of the Sixth See Pee dynasty. Other scholars(I shall name no names) have somehow managed to conclude that the work is a mere compilation of tales whose authorship can never be determined.  However, all agree that the profundity of the work is clearly of such magnitude that the existence of the author is a trivial issue at best.

Perhaps these controversies can be cleared up now that the "Tao of Programming" is about to be published.  If so, then the effort that I have put into preparing the manuscript will not have been in vain.  However, I must confess that it is with some hesitation that I put forward a translation of this classic.  All translations are by definition interpretive, and the flavor of the original can only be echoed faintly and never reproduced in its full richness.

The question has occasionally come up concerning my own beliefs.  I hereby state unequivocally that while I respect the tradition that the "Tao of Programming" represents, I would never adhere to the more radical doctrines that it contains.  In particular, I find the attitude of the text to management and corporations completely reprehensible, though perhaps understandable given the political climate of the times.
With no further ado or further non-ado, I present my humble rendition of the "Tao of Programming".  Those who understand the true nature of Tao will, I trust, be amused by my presumption.

Geoffrey James
Los Angeles, 1986

Table of Contents 

Book 1 -- The Silent Void 
Book 2 -- The Ancient Masters 
Book 3 -- Design 
Book 4 -- Coding 
Book 5 -- Maintenance 
Book 6 -- Management 
Book 7 -- Corporate Wisdom 
Book 8 -- Hardware and Software 
Book 9 -- Epilogue 


THE SILENT VOID  Book One

Thus spake the master programmer:

"When you have learned to snatch the error code from the trap frame, it will be time for you to leave."

1.1
Something mysterious is formed, born in the silent void.  Waiting alone and unmoving, it is at once still and yet in constant motion.  It is the source of all programs.  I do not know its name, so I will call it the Tao of Programming.

If the Tao is great, then the operating system is great.  If the operating system is great, then the compiler is great.  If the compiler is great, then the application is great.  The user is pleased and there is harmony in the world.

The Tao of Programming flows far away and returns on the wind of morning.

1.2
The Tao gave birth to machine language.  Machine language gave birth to the assembler.

The assembler gave birth to the compiler.  Now there are ten thousand languages.

Each language has its purpose, however humble.  Each language expresses the yin and yang of software.  Each language has its place within the Tao.

But do not program in Cobol if you can avoid it.

1.3
In the beginning was the Tao.  The Tao gave birth to Space and Time.  Therefore Space and Time are the yin and Yang of Programming.

Programmers that do not comprehend Tao are always running out of time and space for their programs.  Programmers that comprehend Tao always have enough time and space to accomplish their goals.

How could it be otherwise?

1.4
The wise programmer is told about Tao and follows it.  The average programmer is told about Tao and searches for it.  The foolish programmer is told about Tao and laughs at it. 

If it were not for laughter, there would be no Tao.

The highest sounds are hardest to hear.  Going forward is a way to retreat.  Great talent shows itself late in life.  Even a perfect program still has bugs.

The Tao is hidden beyond all understanding.

THE ANCIENT MASTERS  Book Two

Thus spake the master programmer:

"After three days without programming, life becomes meaningless."

2.1
The programmers of old were mysterious and profound.  We cannot fathom heir thoughts, so all we can do is describe their appearance.

Aware, like a fox crossing the water.  Alert, like a general on the battlefield.  Kind, like a hostess greeting her guests.  Simple, like uncarved blocks of wood.  Opaque, like black pools in darkened caves.  Who can tell the secrets of their hearts and minds?

The answer exists only in Tao.

2.2
Grand Master Turing once dreamed that he was a machine.  When he awoke he exclaimed:

"I don't know whether I am Turing dreaming that I am a machine, or a machine dreaming that I am Turing!"

2.3
A programmer from a very large computer company went to a software conference and then returned to report to his manager, saying: "What sort of programmers work for other computer companies?  They behaved badly and were unconcerned with appearances.  Their hair was long and unkempt and their clothes were wrinkled and old.  They crashed our hospitality suite and they made rude noises during my presentation."

The manager said: "I should never have sent you to the conference.  Those programmers live beyond the physical world.  They consider life absurd, an accidental coincidence.  They come and go without knowing limitations.  Without a care, they live only for their programs.  Why should they bother with social conventions?

Hey are alive within the Tao."

2.4
A novice asked the master: "Here is a programmer who never designs, documents, or tests his programs.  Yet all who know him consider him the one of the best programmers in the world.  Why is this?"

The master replied: "That programmer has mastered the Tao. He has gone beyond the need for design; he does not become angry when the system crashes, but accepts the universe without concern.  He has gone beyond the need for documentation; he no longer cares if anyone sees his code.  He has gone beyond the need for testing; each of his programs are prefect within themselves, serene and elegant, their purpose self-evident.

"Truly, he has entered the mystery of Tao."

DESIGN  Book Three
Thus spake the master programmer:

"When the program is being tested, it is too late to make design changes."

3.1
There was once a man who went to a computer trade show.  Each day as he entered, the man told the guard at the door:

"I am a great thief, renowned for my feats of shoplifting.  Be forewarned, for this trade show shall not escape unplundered."

This speech disturbed the guard greatly, because there were millions of dollars of computer equipment inside, so he watched the man carefully.  But the man merely wandered from booth to booth, humming quietly to himself.

When the man left, the guard took him aside and searched his clothes, but nothing was to be found.

On the next day of the trade show, the man returned and chided the guard, saying: "I escaped with a vast booty yesterday, but today will be even better."  So the guard watched him ever more closely, but to no avail.

On the final day of the trade show, the guard could restrain his curiosity no longer.  "Sir Thief," he said, "I am so perplexed, I cannot live in peace.  Please enlighten me.  What is it that you are stealing?"

The an smiled.  "I am stealing ideas," he said.

3.2
There was once a master programmer who wrote unstructured programs.  A novice programmer, seeking to imitate him, also began to write unstructured programs.  When the novice asked the master to evaluate his progress, the master criticized him for writing unstructured programs, saying: "What is appropriate for the master is not appropriate for the novice.  You must understand Tao before transcending structure."

3.3
There was once a programmer who as attached to the court of the warlord of Wu.  The warlord asked the programmer: "Which is easier to design: an accounting package or an operating system?"

"An operating system," replied the programmer.  The warlord uttered an exclamation of disbelief.

"Surely an accounting package is trivial next to the complexity of an operating system," he said.

"Not so," said the programmer, "when designing an accounting package, the programmer operates as a mediator between people having different ideas: how it must operate, how its reports must appear, and how it mush conform to tax laws.

By contrast, an operating system is not limited by outward appearances.  When designing an operating system, the programmer seeks the simplest harmony between machine and ideas.  This is why an operating system is easier to design."

The warlord of Wu nodded and smiled.  "That is all good and well," he said, "but which is easier to debug?"

The programmer made no reply.

3.4
A manager went to the master programmer and showed him the requirements document for a new application.  The manager asked the master: "How long will it take to design this system if I assign five programmers to it?"

"It will take one year," said the master promptly.

"But we need this system immediately or even sooner!  How long will it take if I assign ten programmers to it?"

The master programmer frowned.  "In that case, it will take two years."

"And what if I assign a hundred programmers to it?"

The master programmer shrugged.  "Then the design will never be completed," he said.

CODING	  Book Four
Thus spake the master programmer:

"A well-written program is its own heaven; a poorly-written program its own hell."

4.1
A program should be light and agile, its subroutines connect like a string of pearls.  The spirit and intent of the program should be retained throughout.  There should be neither too little nor too much, neither needless loops nor useless variables, neither lack of structure nor overwhelming rigidity.

A program should follow the 'Law of Least Astonishment'.  What is this law?

It is simply that the program should always respond to the user in the way that astonishes him least.

A program, no mater how complex, should act as a single unit.  The program should be directed by the logic within rather than by outward appearances.

If the program fails in these requirements it will be in a state of disorder and confusion.  The only way to correct this is to rewrite the program.

4.2
A novice asked the master: "I have a program that sometimes runs and sometimes aborts.  I have followed the rules of programming, yet I am totally baffled.  What is the reason for this?"

The aster replied: "You are confused because you do not understand Tao. Only a fool expects rational behavior from his fallow humans.  Why do you expect it from a machine hat humans have constructed?  Computers simulate determinism; only Tao is perfect.

The rules of programming are transitory; only Tao is eternal.  Therefore you must contemplate Tao before you receive enlightenment."

"But how will I know when I have received enlightenment?" asked the novice.

"Your program will then run correctly," replied the master.

4.3
A master was explaining the nature of Tao to one of his novices.  "The Tao is embodied in all software