The Technical Debt Trap

#DevBootcamp / #TechnicalDebtTrap / @DocOnDev
The
technical Debt
Trap

Doc Norton, CEO
doc@wearecto2.com
@DocOnDev

what is technical debt?

– Ward Cunningham
OOPSLA ‘92
Shipping first time code is like
going into debt.

going into debt. A little debt
speeds development so long as
it is paid back promptly with a
rewrite.
– Ward Cunningham
OOPSLA ‘92

going into debt. A little debt
speeds development so long as
it is paid back promptly with a
rewrite.
The danger occurs when the
debt is not repaid. Every minute
spent on not-quite-right code
counts as interest on that debt.
– Ward Cunningham
OOPSLA ‘92

The danger occurs
when the debt is not
repaid. Every minute
spent on not-quite-
right code counts as
interest on that debt.
– Ward Cunningham
OOPSLA ‘92

Technical debt is

Technical debt is
good

Technical debt is good

Technical debt is
a strategic decision

Technical debt is
a strategic decision
• Allow for Rapid Delivery
• To Elicit Quick Feedback
• And Correct Design

technical debt is
an indication of learning

technical debt is
an indication of learning
• Now know what you need
• Implementation doesn’t match

technical debt is a metaphor

metaphors rock
we reason by analogy
Building on a
weak foundation
Puts pressure on our design
Can’t keep running at this pace
It’s raining men
(hallelujah)

metaphorphosis
when metaphors go wrong
Credit CardSHORT-TERM
Long-Term
Return on
Investment
OPERATIONALHOME LOAN
Loan Shark
PRAGMATIC
LEVERAGE
Intentional AUTO LOAN
FRAUDULENT
VOLUNTARY
PYRAMID SCHEME
Prudent
Student Loan
HIGH INTEREST
INADVERTENT
RECKLESS DEBT IN
THE THIRD
QUADRANT

metaphorphosis
when metaphors go wrong
“quick and dirty”
- Martin Fowler
“sloppy”
- David Laribee
“just hack it in”
- Steve McConnell
“CUT A LOT OF CORNERS”
- James Shore

technical debt quadrant
Reckless
Inadvertent
Prudent
Deliberate
“We don’t have time
for design”
“We must ship now and
deal with
consequences”
“Now we know how we
should have done it”
“What’s Layering?”

– Ward Cunningham
Youtube ‘09
[Many] have explained
the debt metaphor and
confused it with the
idea that you could
write code poorly with
the intention of doing a
good job later.

– Ward Cunningham
Youtube ‘09
confused the
debt metaphor
with the idea that
you could write
code poorly

– Ward Cunningham
Youtube ‘09
The ability to pay back
debt [...] depends upon
you writing code that is
clean enough to be
able to refactor as you
come to understand
your problem.

– Ward Cunningham
twitter ‘09
Dirty code is to
technical debt as the
pawn broker is to
financial debt.

– Ward Cunningham
twitter ‘09
Dirty code is to
technical debt as the
pawn broker is to
financial debt.
Don’t think you are
ever going to get your
code back.

technical debt?
Ask yourself…

technical debt?
Ask yourself…
• Is the code clean?
• Is the code tested?
• Is there a learning objective or event?
• Is there a plan for payback?
• Is the business truly informed?

technical debt?
If you say no to even one…

technical debt?
If you say no to even one…
... then you don’t have Technical Debt

mess (noun)

mess (noun)
• Disorderly accumulation, heap, or jumble
• A state of embarrassing confusion
• An unpleasant or difficult situation

cruft (noun)

cruft (noun)
• An unpleasant substance
• The result of shoddy construction
• Redundant, old or improperly written code

But, It’s Just
semantics

It’s not Just
semantics

It’s not Just
semantics
Technical Debt is Good

It’s not Just
semantics
Technical Debt is GoodQuick and Dirty is Technical Debt

It’s not Just
semantics
Quick and Dirty is Good

Reckless
Inadvertent
Prudent
Deliberate
for design”
“Let’s deploy and
gather more
information”

technical debt in other fields

Technical Debt in other fields

RECKLESS AND DELIBERATE

RECKLESS AND INADVERTENT

Reckless
Inadvertent
Prudent
Deliberate
for design”
gather more
information”
IRRESPONSIBLE

Reckless
Inadvertent
Prudent
Deliberate
for design”
gather more
information”
IRRESPONSIBLE
INCOMPETENT

Reckless
Inadvertent
Prudent
Deliberate
for design”
gather more
information”
IRRESPONSIBLE
INCOMPETENT
TECHNICAL
DEBT

cruft or debt?

DataSet aDs, qDs;
aDs = _dbConnector.UpdateAgentList();
qDs = _dbConnector.GetQueueList();
foreach (DataTable aTable in aDs.Tables) {
foreach (DataRow aRow in aTable.Rows) {
foreach (DataColumn aColumn in aTable.Columns) {
DataSet asDs = _dbConnector.GetAgentSkills(aRow[aColumn].ToString());//AgentId
foreach (DataTable asTable in asDs.Tables) {
foreach (DataRow asRow in asTable.Rows) {
foreach (DataColumn asColumn in asTable.Columns) {
foreach (DataTable qTable in qDs.Tables) {
foreach (DataRow qRow in qTable.Rows) {
foreach (DataColumn qColumn in qTable.Columns) {
DataSet sqDs = _dbConnector.GetSkillsForQueue(qRow[qColumn].ToString());
foreach (DataTable sqTable in sqDs.Tables) {
foreach (DataRow sqRow in sqTable.Rows) {
foreach (DataColumn sqColumn in sqTable.Columns) {
foreach (string skill in sqRow[sqColumn].ToString().Split(paramDelimStr)) {
if (skill == asRow[asColumn].ToString()) {
try {
_dbConnector.SetAgentQueueSkill(aRow[aColumn].ToString(),
qRow[qColumn].ToString(),
skill);
}
catch { continue; }
}
}
}
}
}
}
}
}
}
}
}
}
}
}
cruft or debt?

DataSet aDs, qDs;
try {
skill);
}
catch { continue; }
}
}
}
}
}
}
}
}
}
}
}
}
}
}

DataSet aDs, qDs;
try {
skill);
}
catch { continue; }
}
} } } } } } } } } } } } }

DataSet aDs, qDs, asDs, sqDs;
foreach (DataRow aRow in aDS.Tables[0].Rows) {
String agentID = aRow[“AgentId”].ToString();
asDs = _dbConnector.GetAgentSkills(agentID);
foreach (DataRow asRow in asDs.Tables[0].Rows) {
String agentSkill = asRow[“Skill”].ToString();
foreach (DataRow qRow in qDs.Tables[0].Rows) {
queueName = qRow[“QueueName”].ToString();
sqDs = _dbConnector.GetSkillsForQueue(queueName);
foreach (DataRow sqRow in sqDs.Tables[0].Rows) {
foreach (string skill in sqRow[“Skills”].ToString().Split(paramDelimStr)) {
if (skill == agentSkill) {
try { _dbConnector.SetAgentQueueSkill(agentID, queueName, skill); }
catch { continue; }
} } } } } }

AgentList agents = new AgentList(_dbConnector.UpdateAgentList());
QueueList queues = new QueueList(_dbConnector.GetQueueList());
foreach (Agent agent in agents) {
foreach (Skill agentSkill in agent.skills) {
foreach (Queue queue in queues) {
foreach (Skill queueSkill in queue.skills.Where(x => x == agentSkill)) {
try {_dbConnector.SetAgentQueueSkill(agent.agentID, queue.name, agentSkill); }
catch { continue; }
}
}
}
}

if ((customer.state == “AL” && customer.type ==
CustomerType.GENERAL_AGENT && customer.revenue > 100000)
|| (customer.type == CustomerType.RETRO_AGENT &&
(customer.state == “WI” || customer.state == “IL”))
|| (customer.type == CustomerType.FED_MANAGEMENT &&
customer.revenue > 150000)) { ... }
cruft or debt?

// If customer is Federally Regulated
if ((customer.state == “AL” && customer.type ==
CustomerType.GENERAL_AGENT && customer.revenue > 100000)
|| (customer.type == CustomerType.RETRO_AGENT &&
(customer.state == “WI” || customer.state == “IL”))
|| (customer.type == CustomerType.FED_MANAGEMENT &&
customer.revenue > 150000)) { ... }

if (customer.isFederallyRegulated()) { ... }

double getSpeed() {
switch (_type) {
case EUROPEAN:
return getBaseSpeed();
case AFRICAN:
return getBaseSpeed() - getLoadFactor() * _numberOfCoconuts;
case NORWEGIAN_BLUE:
return (_isNailed) ? 0 : getBaseSpeed(_voltage);
}
throw new RuntimeException ("Should be unreachable");
}
http://www.refactoring.com/catalog/replaceConditionalWithPolymorphism.html
cruft or debt?

class Swallow ...
double getSpeed() { return getBaseSpeed(); }
end class
class EuropeanSwallow ...
end class
class AfricanSwallow ...
double getSpeed() { return super.getSpeed - coconutLoad(); }
double coconutLoad() { return getLoadFactor() * _numberOfCoconuts; }
end class
class NorwegianSwallow ...
double getSpeed() { return (_isNailed) ? 0 : getBaseSpeed(_voltage); }
end class

cruft is a bad decision

cruft is a bad decision
• You are a professional developer
• You’re going to create unintentional cruft
• You have to clean up the existing cruft

The Trap

The Trap
• Precedent for speed over quality
• Expectation of increased velocity
• Cruft slows you down
• Must write more cruft to keep up
• Ask permission to do your job correctly

failing strategies

winning strategy
Clean Constantly

winning strategy
Clean Constantly
• Never make an intentional mess
• Monitor your “Technical Debt”
• Follow the Boy Scout Rule
• Remember quality is your responsibility

winning strategy
Clean Constantly
• Never make an intentional mess
• Monitor your “Technical Debt”
• Follow the Boy Scout Rule
• Remember quality is your responsibility
• NEVER ask permission to do your job correctly

Monitor your cruft

Monitor your cruft
• Code Coverage
• Code Complexity
• Coupling
• Maintainability
• Monitor Trends, Not Points

review
Technical Debt
Cruft

review
Technical Debt
• A strategic design decision
• Requires business to be informed
• Includes a pay-back plan
Cruft
• Happens
• Needs to be monitored and cleaned
• Is NOT Technical Debt

review
Technical Debt
• A strategic design decision
• Requires business to be informed
• Includes a pay-back plan
Cruft
• Happens
• Needs to be monitored and cleaned
• Is NOT Technical Debt
NEVER
ask
perm
issio
n
to
do
yo
ur
jo
b
co
rrectly

comments
or
questions?
Doc Norton, CEO
doc@wearecto2.com
@DocOnDev

Thank You!
Doc Norton, CEO
doc@wearecto2.com
@DocOnDev

• OOPSLA 92 Paper - http://dl.acm.org/citation.cfm?
id=157715, http://c2.com/doc/oopsla92.html
• Ward Cunningham Technical Debt Video - http://
www.youtube.com/watch?
v=pqeJFYwnkjE&feature=player_embedded
• Ward Cunningham Twitter - http://twitter.com/
WardCunningham/status/3742903303
• Technical Debt Quadrant - http://martinfowler.com/
bliki/TechnicalDebtQuadrant.html
• James Shore - http://jamesshore.com/Blog/
CardMeeting/Voluntary-Technical-Debt.html
• Martin Fowler - http://www.martinfowler.com/bliki/
TechnicalDebt.html
• David Larabee - http://msdn.microsoft.com/en-us/
magazine/ee819135.aspx
• Steve McConnell - http://blogs.construx.com/blogs/
stevemcc/archive/2007/11/01/technical-debt-2.aspx
• Jon Stewart - http://big.assets.huffingtonpost.com/
JonConfused.gif
• Cruft Example 1 - http://thedailywtf.com/Series/
2010/3/CodeSOD.aspx
• Debt Threshold - http://blog.castsoftware.com/wp-
content/uploads/2011/04/Technical-Debt-Software-
Quality1.jpg
• Hardening Sprints - http://blog.castsoftware.com/wp-
content/uploads/2011/04/Technical-Debt-Software-
Quality1.jpg

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