karl@grebyn.UUCP (09/25/87)
[Can you think of a better place for this? I did forward to
soft-eng@xx.lcs.mit.edu.]
Communications of the ACM, September 1987, Volume 30, Number 9, p. 750-751
president's letter
by Paul Abrahams, acm president
Copyright 1987 by the Association for Computing Machinery, Inc. Copying
without fee is permitted provided that the copies are not made or
distributed for direct commercial advantage and credit to the source is
given.
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A Gown for the Princess: A Parable for Software Engineers
Once upon a time, there lived a king who had a beautiful daughter. The king
wished nothing more than to make her happy, and so he resolved that the
princess should have a fine new gown that would match her beauty. He
summoned the wisest and most silled tailor in all of his kingdom to make a
gown for the princess. "My daughter shall have the finest gown in the
land," declared the king.
"Before I can make such a gown," said the tailor, "I must know what it is
that you require." And the tailor discoursed at length about the materials
that might be used, the cuts and patterns to be chosen, the method of
joining and seaming, the decorations, and other such matters. He spoke of
gores and pleats, of hems and stitches, of darts and shirring, of embroidery
and lace. The poor king knew nothing of such matters. "I just want a
beautiful gown for my daughter!" he exclaimed. "I shall do my best," said
the tailor."
The next week the tailor returned to the palace. He brought a large sheaf
of documents and presented them to the king. "These are the specifications
I propose for the gown, your Majesty. I hope it is what you want. It shall
be completed in a year's time. And for my labors and the labors of my
assistants, I must humbly ask your Majesty for fifty thousand ducats."
"These tailors charge the earth and the sky," thought the king, "but there
is nothing to do but to pay it and hope for the best." The king nodded
sadly, "It shall be as you propose," said the king, and he placed the royal
seal upon the specification.
The tailor then appointed himself as Chief Tailor and summoned a score of
apprentice tailors to assist him. He explained to them how, together, they
would create the gown. "Let us decompose the task into its parts: the
sleeves, the bodice, the waist, the skirt, and the adornments. Each one of
you is to prepare a part of the gown, and my task is to specify the parts
and discern how they are to be fitted together. But hasten not to your loom
and your table; we first must plan how each part is to be prepared and
decompose the task until the smallest detail is known.
We must verify beyond the shadow of doubt that the gown we create will meet
its specification. To that end we must prove that all its parts will fit
together and that each part is as the larger design would have it. Through
such verification we may know, before the first stitch is taken, that the
gown will render honor to the princess of the realm and be as the king has
ordered."
Months went by, and the Chief Tailor and his assistants filled sheets of
paper with drawings of the gown and of all its parts. Yet the fine fabrics
purchased for the gown remained in the storehouse, and not a stitch had been
sewn. The king began to worry that the gown would not be completed within
the year. He summoned the Chief Tailor to the court and asked why the gown
had not yet been started. "The execution shall follow upon the plan, as the
night upon the day," said the Chief Tailor. "I shall not take needle and
thread to hand until the gown has been completely designed." And so it was.
But at last the design was done, and the great enterprise began to take
shape. Fabrics were woven, and the team of tailors went busily about their
work of cutting, sewing, and shaping. As the different parts of the gown
were completed, the tailors brought them to the Chief Tailor for assembly.
Here was the most difficult part of the whole effort, for it seemed that,
whenever two parts were joined, a piece of fabric remained on one side or
the other. Many times the tailors had to take back their work and resew it,
and arguments broke out among them as to who was at fault.
One day the Chief Tailor came to the king. "Alas, your Majesty, the
allotted sum is not sufficient to complete the gown. For the princess has
grown in girth since the measurements were made, and it is now necessary to
alter the plan. I must ask an additional thousand ducats if it is to be
completed on time." Sadly the king nodded. "Go and do it, then," he said.
At last, after a year and a half, the gown was completed and brought to the
princess for a demonstration. Alas, the poor girl was unable to put it on,
for the chief tailor, in his quest for excellence of shape, had forgotten to
provide any buttons. Hastily the tailor modified the gown, and the princess
then showed it to the king. "Is the gown acceptable?" asked the Chief
Tailor. "It is, indeed," answered the king. But the king was troubled at
heart, for somehow the gown did not look at all like what he had expected.
Several days later the princess was walking in the garden of the palace,
wearing her new gown. As she reached up to pluck a grape, the top of the
gown slid down, exposing her bosom for all to view. The king was very
distressed and angrily summoned the Chief Tailor. "What kind of a gown have
you made for my daughter!" he exclaimed. "Not only has it made her look
foolish, but I paid you fifty thousand ducats for it!"
"Prithee, your Majesty," said the tailor. "The gown was made according to
the specifications that you agreed to. Nowhere did we speak of this matter,
that the gown should remain in one place only. Indeed, 'tis not a fault but
a feature of the gown, that your daughter's beauty should be displayed to
all the folk of the land. But, if your Majesty desires to alter the gown, I
must humbly request another fifteen hundred ducats for the immense labor
necessary to meet your wishes." Sadly the king nodded. "Go and do it,
then," he said.
A few years later, the Chief Tailor was turned into a frog by a disgruntled
witch whose affections he had spurned. Hardly had the Chief Tailor been
transformed than strange stains and rips appeared in the gown. The Backup
Tailor, who had been appointed by the Chief Tailor to maintain the gown,
examined it closely, seeking to repair it. But the documents that described
the design were not to be found, and the Backup Tailor finally had to give
up. The princess put the gown in the back of her closet, and there it
remains to this very day.
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-- Karl --
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