Index
## detection, 237–238
++ (pre- or post-increment) operator, 325, 326
A
aborted computation, 109
abstract classes, 149, 271, 290
ABSTRACT FACTORY pattern, 38, 156, 273, 274
abstract interfaces, 94
abstract methods
adding to ArgumentMarshaler, 234–235
modifying, 282
abstract terms, 95
abstraction
classes depending on, 150
code at wrong level of, 290–291
descending one level at a time, 37
functions descending only one level of, 304–306
mixing levels of, 36–37
names at the appropriate level of, 311
separating levels of, 305
wrapping an implementation, 11
abstraction levels
raising, 290
separating, 305
accessor functions, Law of Demeter and, 98
accessors, naming, 25
Active Records, 101
adapted server, 185
affinity, 84
Agile Software Development: Principles, Patterns, Practices (PPP), 15
algorithms
correcting, 269–270
repeating, 48
understanding, 297–298
ambiguities
in code, 301
ignored tests as, 313
amplification comments, 59
analysis functions, 265
“annotation form”, of AspectJ, 166
AOP (aspect-oriented programming), 160, 163
APIs. See also public APIs
calling a null-returning method from, 110
specialized for tests, 127
wrapping third-party, 108
applications
decoupled from Spring, 164
decoupling from construction details, 156
infrastructure of, 163
keeping concurrency-related code separate, 181
arbitrary structure, 303–304
args array, converting into a list, 231–232
Args class
constructing, 194
implementation of, 194–200
rough drafts of, 201–212, 226–231
listing, 198–200
merging exceptions into, 239–242
argument(s)
flag, 41
for a function, 40
in functions, 288
monadic forms of, 41
reducing, 43
argument lists, 43
argument objects, 43
argument types
negative impact of, 208
ArgumentMarshaler class
adding the skeleton of, 213–214
birth of, 212
ArgumentMarshaler interface, 197–198
arrays, moving, 279
art, of clean code, 6–7
artificial coupling, 293
AspectJ language, 166
aspect-oriented programming (AOP), 160, 163
aspects
in AOP, 160–161
“first-class” support for, 166
assert statements, 130–131
assertEquals, 42
assertions, using a set of, 111
assignments, unaligned, 87–88
atomic operation, 323–324
attributes, 68
authors of JUnit, 252
programmers as, 13–14
authorship statements, 55
automated code instrumentation, 189–190
automated suite, of unit tests, 124
B
bad code, 3–4. See also dirty code; messy code
degrading effect of, 250
example, 71–72
experience of cleaning, 250
not making up for, 55
bad comments, 59–74
banner, gathering functions beneath, 67
BDUF (Big Design Up Front), 167
beans, private variables manipulated, 100–101
Beck, Kent, 3, 34, 71, 171, 252, 289, 296
behaviors, 288–289
Big Design Up Front (BDUF), 167
blank lines, in code, 78–79
blocks, calling functions within, 35
Booch,Grady, 8–9
boolean, passing into a function, 41
boolean map, deleting, 224
boolean output, of tests, 132
boundaries
clean, 120
exploring and learning, 116
incorrect behavior at, 289
separating known from unknown, 118–119
boundary condition errors, 269
boundary conditions
encapsulating, 304
testing, 314
boundary tests, easing a migration, 118 “Bowling Game”, 312
following, 284
satisfying, 265
broken windows metaphor, 8
bucket brigade, 303
BUILD-OPERATE-CHECK pattern, 127
builds, 287
business logic, separating from error handling, 109
bylines, 68
byte-manipulation libraries, 161, 162–163
The C++ Programming Language, 7
calculations, breaking into intermediate values, 296
call stack, 324
Callable interface, 326
caller, cluttering, 104
calling hierarchy, 106
calls, avoiding chains of, 98
caring, for code, 10
Cartesian points, 42
CAS operation, as atomic, 328
change(s)
isolating from, 149–150
large number of very tiny, 213
organizing for, 147–150
tests enabling, 124
change history, deleting, 270
check exceptions, in Java, 106
clarification, comments as, 57
class names, 25
classes
cohesion of, 140–141
creating for bigger concepts, 28–29
declaring instance variables, 81
enforcing design and business rules, 115
exposing internals of, 294
instrumenting into ConTest, 342
minimizing the number of, 176
nonthread-safe, 328–329
as nouns of a language, 49
organization of, 136
organizing to reduce risk of change, 147
supporting advanced concurrency design, 183
classification, of errors, 107
clean boundaries, 120
clean code
art of, 6–7
described, 7–12
writing, 6–7
clean tests, 124–127
cleanliness
acquired sense of, 6–7
tied to tests, 9
cleanup, of code, 14–15
clever names, 26
client, using two methods, 330
client code, connecting to a server, 318
client-based locking, 185, 329, 330–332
clientScheduler, 320
client/server application, concurrency in, 317–321
Client/Server nonthreaded, code for, 343–346
client-server using threads, code changes, 346–347
closing braces, comments on, 67–68
clutter
Javadocs as, 276
keeping free of, 293
code, 2
bad, 3–4
Beck’s rules of, 10
dead, 292
explaining yourself in, 55
expressing yourself in, 54
formatting of, 76
implicity of, 18–19
jiggling, 190
making readable, 311
necessity of, 2
reading from top to bottom, 37
technique for shrouding, 20
third-party, 114–115
width of lines in, 85–90
at wrong level of abstraction, 290–291
code bases, dominated by error handling, 103
code changes, comments not always following, 54
code completion, automatic, 20
code coverage analysis, 254–256
code instrumentation, 188–190 “code sense”, 6, 7
code smells, listing of, 285–314
coding standard, 299
cohesion
of classes, 140–141
maintaining, 141–146
command line arguments, 193–194
commands, separating from queries, 45–46
comment header standard, 55–56
comment headers, replacing, 70
commented-out code, 68–69, 287
commenting style, example of bad, 71–72
comments
amplifying importance of something, 59
bad, 59–74
deleting, 282
as failures, 54
good, 55–59
heuristics on, 286–287
HTML, 69
inaccurate, 54
informative, 56
journal, 63–64
legal, 55–56
mandated, 63
misleading, 63
mumbling, 59–60
as a necessary evil, 53–59
noise, 64–66
not making up for bad code, 55
obsolete, 286
poorly written, 287
proper use of, 54
redundant, 60–62, 272, 275, 286–287
restating the obvious, 64
separated from code, 54
TODO, 58–59
too much information in, 70
venting in, 65
writing, 287
“communication gap”, minimizing, 168
Compare and Swap (CAS) operation, 327–328
ComparisonCompactor module, 252–265
defactored, 256–261
final, 263–265
interim, 261–263
original code, 254–256
compiler warnings, turning off, 289
complex code, demonstrating failures in, 341
complexity, managing, 139–140
computer science (CS) terms, using for names, 27
concepts
keeping close to each other, 80
naming, 19
one word per, 26
separating at different levels, 290
spelling similar similarly, 20
vertical openness between, 78–79
conceptual affinity, of code, 84
concerns
cross-cutting, 160–161
separating, 154, 166, 178, 250
concrete classes, 149
concrete details, 149
concrete terms, 94
concurrency
defense principles, 180–182
issues, 190
motives for adopting, 178–179
myths and misconceptions about, 179–180
concurrency code
compared to nonconcurrency-related code, 181
focusing, 321
concurrent algorithms, 179
concurrent applications, partition behavior, 183
concurrent code
breaking, 329–333
defending from problems of, 180
flaws hiding in, 188
concurrent programming, 180
Concurrent Programming in Java: Design Principles and Patterns, 182, 342
concurrent programs, 178
concurrent update problems, 341
ConcurrentHashMap implementation, 183
conditionals
avoiding negative, 302
configurable data, 306
configuration constants, 306
consequences, warning of, 58
consistency
in code, 292
of enums, 278
in names, 40
consistent conventions, 259
constants
versus enums, 308–309
hiding, 308
keeping at the appropriate level, 83
leaving as raw numbers, 300
not inheriting, 307–308
passing as symbols, 276
turning into enums, 275–276
construction
separating with factory, 156
of a system, 154
constructor arguments, 157
constructors, overloading, 25
consumer threads, 184
context
adding meaningful, 27–29
not adding gratuitous, 29–30
providing with exceptions, 107
continuous readers, 184
control variables, within loop statements, 80–81
convenient idioms, 155
convention(s)
following standard, 299–300
over configuration, 164
structure over, 301
using consistent, 259
convoluted code, 175
copyright statements, 55
cosmic-rays. See one-offs
CountDownLatch class, 183
coupling. See also decoupling; temporal coupling; tight coupling
artificial, 293
hidden temporal, 302–303
lack of, 150
coverage patterns, testing, 314
coverage tools, 313 “crisp abstraction”, 8–9
cross-cutting concerns, 160
Cunningham, Ward, 11–12
cuteness, in code, 26
D
dangling false argument, 294
data
abstraction, 93–95
copies of, 181–182
encapsulation, 181
limiting the scope of, 181
sets processed in parallel, 179
data structures. See also structure(s)
defined, 95
interfaces representing, 94
treating Active Records as, 101
data transfer-objects (DTOs), 100–101, 160
database normal forms, 48
DateInterval enum, 282–283
DAY enumeration, 277
DayDate class, running SerialDate as, 271
DayDateFactory, 273–274
dead functions, 288
deadly embrace. See circular wait
debugging, finding deadlocks, 336
decision making, optimizing, 167–168
decisions, postponing, 168
declarations, unaligned, 87–88
DECORATOR objects, 164
DECORATOR pattern, 274
decoupled architecture, 167
decoupling, from construction details, 156
decoupling strategy, concurrency as, 178
default constructor, deleting, 276
degradation, preventing, 14
deletions, as the majority of changes, 250
density, vertical in code, 79–80
dependencies
finding and breaking, 250
injecting, 157
logical, 282
making logical physical, 298–299
between methods, 329–333
between synchronized methods, 185
Dependency Injection (DI), 157
Dependency Inversion Principle (DIP), 15, 150
dependency magnet, 47
dependent functions, formatting, 82–83
derivatives
base classes depending on, 291
base classes knowing about, 273
of the exception class, 48
moving set functions into, 232, 233–235
pushing functionality into, 217
description
of a class, 138
overloading the structure of code into, 310
descriptive names
choosing, 309–310
using, 39–40
design(s)
of concurrent algorithms, 179
minimally coupled, 167
principles of, 15
design patterns, 290
details, paying attention to, 8
DI (Dependency Injection), 157
Dijkstra, Edsger, 48
dining philosophers execution model, 184–185
DIP (Dependency Inversion Principle), 15, 150
dirty code. See also bad code; messy code
dirty code, cleaning, 200
dirty tests, 123
disinformation, avoiding, 19–20
distance, vertical in code, 80–84
distinctions, making meaningful, 20–21
domain-specific languages (DSLs), 168–169
domain-specific testing language, 127
DoubleArgumentMarshaler class, 238
DRY principle (Don’t Repeat Yourself), 181, 289
DTOs (data transfer objects), 100–101, 160
dummy scopes, 90
duplicate if statements, 276
duplication
of code, 48
in code, 289–290
eliminating, 173–175
focusing on, 10
reduction of, 48
strategies for eliminating, 48
dyadic argument, 40
dyadic functions, 42
dynamic proxies, 161
E
e, as a variable name, 22
Eclipse, 26
edit sessions, playing back, 13–14
efficiency, of code, 7
EJB architecture, early as over-engineered, 167
EJB standard, complete overhaul of, 164
EJB2 beans, 160
EJB3, Bank object rewritten in, 165–166
“elegant” code, 7
emergent design, 171–176
encapsulation, 136
of boundary conditions, 304
breaking, 106–107
of conditionals, 301
encodings, avoiding, 23–24, 312–313
entity bean, 158–160
enum(s)
changing MonthConstants to, 272
using, 308–309
enumeration, moving, 277
environment, heuristics on, 287
environment control system, 128–129
envying, the scope of a class, 293
error check, hiding a side effect, 258
Error class, 47–48
error code constants, 198–200
error codes
implying a class or enum, 47–48
preferring exceptions to, 46
returning, 103–104
reusing old, 48
separating from the Args module, 242–250
error detection, pushing to the edges, 109
error flags, 103–104
error processing, testing, 238–239
errorMessage method, 250
errors. See also boundary condition errors; spelling errors; string comparison errors classifying, 107
Evans, Eric, 311
events, 41
exception classification, 107
exception clauses, 107–108
exception management code, 223
exceptions
instead of return codes, 103–105
narrowing the type of, 105–106
preferring to error codes, 46
providing context with, 107
separating from Args, 242–250
unchecked, 106–107
execution, possible paths of, 321–326
execution models, 183–185
Executor framework, 326–327
ExecutorClientScheduler.java, 321
explanation, of intent, 56–57
explanatory variables, 296–297
explicitness, of code, 19
expressive code, 295
expressiveness
in code, 10–11
ensuring, 175–176
Extract Method refactoring, 11
Extreme Programming Adventures in C#, 10
Extreme Programming Installed, 10
“eye-full”, code fitting into, 79–80
F
factories, 155–156
factory classes, 273–275
failure
to express ourselves in code, 54
patterns of, 314
tolerating with no harm, 330
false argument, 294
fast tests, 132
fast-running threads, starving longer running, 183
fear, of renaming, 30
Feathers, Michael, 10
feature envy
eliminating, 293–294
smelling of, 278
file size, in Java, 76
final keywords, 276
F.I.R.S.T. acronym, 132–133
First Law, of TDD, 122
FitNesse project
coding style for, 90
function in, 32–33
invoking all tests, 224
focussed code, 8
foreign code. See third-party code
formatting
horizontal, 85–90
purpose of, 76
Uncle Bob’s rules, 90–92
vertical, 76–85
formatting style, for a team of developers, 90
Fortran, forcing encodings, 23
frame, 324
function arguments, 40–45
function call dependencies, 84–85
function headers, 70
function signature, 45
functionality, placement of, 295–296
functions
breaking into smaller, 141–146
calling within a block, 35
dead, 288
defining private, 292
descending one level of abstraction, 304–306
dyadic, 42
eliminating extraneous if statements, 262
establishing the temporal nature of, 260
formatting dependent, 82–83
gathering beneath a banner, 67
heuristics on, 288
intention-revealing, 19
keeping small, 175
length of, 34–35
moving, 279
number of arguments in, 288
one level of abstraction per, 36–37
in place of comments, 67
renaming for clarity, 258
rewriting for clarity, 258–259
sections within, 36
small as better, 34
structured programming with, 49
understanding, 297–298
as verbs of a language, 49
writing, 49
futures, 326
G
Gamma, Eric, 252
general heuristics, 288–307
generated byte-code, 180
generics, improving code readability, 115
get functions, 218
getBoolean function, 224
GETFIELD instruction, 325, 326
getNextId method, 326
getState function, 129
given-when-then convention, 130
glitches. See one-offs
global setup strategy, 155
“God class”, 136–137
good comments, 55–59
goto statements, avoiding, 48, 49
grand redesign, 5
gratuitous context, 29–30
H
hand-coded instrumentation, 189
HashTable, 328–329
headers. See comment headers; function headers
heuristics
general, 288–307
listing of, 285–314
hidden temporal coupling, 259, 302–303
hidden things, in a function, 44
hiding
implementation, 94
structures, 99
hierarchy of scopes, 88
HN. See Hungarian Notation
horizontal alignment, of code, 87–88
horizontal formatting, 85–90
horizontal white space, 86
HTML, in source code, 69
Hungarian Notation (HN), 23–24, 295
hybrid structures, 99
I
if statements
duplicate, 276
eliminating, 262
if-else chain
appearing again and again, 290
eliminating, 233
ignored tests, 313
implementation
duplication of, 173
encoding, 24
exposing, 94
hiding, 94
wrapping an abstraction, 11
Implementation Patterns, 3, 296
implicity, of code, 18
import lists
avoiding long, 307
shortening in SerialDate, 270
imports, as hard dependencies, 307
imprecision, in code, 301
inaccurate comments, 54
inappropriate information, in comments, 286
inappropriate static methods, 296
include method, 48
inconsistency, in code, 292
inconsistent spellings, 20
incrementalism, 212–214
indent level, of a function, 35
indentation, of code, 88–89
indentation rules, 89
independent tests, 132
information
inappropriate, 286
informative comments, 56
inheritance hierarchy, 308
inobvious connection, between a comment and code, 70
input arguments, 41
instance variables
in classes, 140
declaring, 81
hiding the declaration of, 81–82
passing as function arguments, 231
proliferation of, 140
instrumented classes, 342
insufficient tests, 313
integer argument(s)
defining, 194
integrating, 224–225
integer argument functionality, moving into ArgumentMarshaler, 215–216
integer argument type, adding to Args, 212
integers, pattern of changes for, 220
IntelliJ, 26
intent
explaining in code, 55
explanation of, 56–57
obscured, 295
intention-revealing function, 19
intention-revealing names, 18–19
interface(s)
defining local or remote, 158–160
encoding, 24
implementing, 149–150
representing abstract concerns, 150
turning ArgumentMarshaler into, 237
well-defined, 291–292
writing, 119
internal structures, objects hiding, 97
intersection, of domains, 160
intuition, not relying on, 289
inventor of C++, 7
Inversion of Control (IoC), 157
InvocationHandler object, 162
I/O bound, 318
isolating, from change, 149–150
isxxxArg methods, 221–222
iterative process, refactoring as, 265
J
jar files, deploying derivatives and bases in, 291
Java
aspects or aspect-like mechanisms, 161–166
heuristics on, 307–309
as a wordy language, 200
Java 5, improvements for concurrent development, 182–183
Java 5 Executor framework, 320–321
Java 5 VM, nonblocking solutions in, 327–328
Java AOP frameworks, 163–166
Java programmers, encoding not needed, 24
Java proxies, 161–163
Java source files, 76–77
javadocs
as clutter, 276
in nonpublic code, 71
preserving formatting in, 270
in public APIs, 59
requiring for every function, 63
java.util.concurrent package, collections in, 182–183
JBoss AOP, proxies in, 163
JCommon library, 267
JCommon unit tests, 270
JDK proxy, providing persistence support, 161–163
jiggling strategies, 190
JNDI lookups, 157
journal comments, 63–64
JUnit, 34
JUnit framework, 252–265
Just-In-Time Compiler, 180
K
keyword form, of a function name, 43
L
L, lower-case in variable names, 20
language design, art of programming as, 49
languages
appearing to be simple, 12
level of abstraction, 2
multiple in one source file, 288
multiples in a comment, 270
last-in, first-out (LIFO) data structure, operand stack as, 324
LAZY INITIALIZATION/EVALUATION idiom, 154
LAZY-INITIALIZATION, 157
LeBlanc’s law, 4
legacy code, 307
legal comments, 55–56
level of abstraction, 36–37
levels of detail, 99
lexicon, having a consistent, 26
lines of code
duplicating, 173
width of, 85
list(s)
of arguments, 43
meaning specific to programmers, 19
returning a predefined immutable, 110
literate code, 9
literate programming, 9
Literate Programming, 141
local comments, 69–70
local variables, 324
declaring, 292
at the top of each function, 80
locks, introducing, 185
log4j package, 116–118
logical dependencies, 282, 298–299
LOGO language, 36
long descriptive names, 39
long names, for long scopes, 312
loop counters, single-letter names for, 25
M
magic numbers
obscuring intent, 295
replacing with named constants, 300–301
main function, moving construction to, 155, 156
managers, role of, 6
mandated comments, 63
manual control, over a serial ID, 272
Map
adding for ArgumentMarshaler, 221
methods of, 114
maps, breaking the use of, 222–223
marshalling implementation, 214–215
meaningful context, 27–29
member variables
f prefix for, 257
prefixing, 24
renaming for clarity, 259
mental mapping, avoiding, 25
messy code. See also bad code; dirty code total cost of owning, 4–12
method invocations, 324
method names, 25
methods
affecting the order of execution, 188
calling a twin with a flag, 278
changing from static to instance, 280
of classes, 140
dependencies between, 329–333
eliminating duplication between, 173–174
minimizing assert statements in, 176
naming, 25
tests exposing bugs in, 269
minimal code, 9
misleading comments, 63
misplaced responsibility, 295–296, 299
MOCK OBJECT, assigning, 155
monadic argument, 40
monadic forms, of arguments, 41
monads, converting dyads into, 42
Monte Carlo testing, 341
Month enum, 278
MonthConstants class, 271
multithread aware, 332
multithread-calculation, of throughput, 335
multithreaded code, 188, 339–342
mumbling, 59–60
mutators, naming, 25
mutual exclusion, 183, 336, 337
N
named constants, replacing magic numbers, 300–301
name-length-challenged languages, 23
names
abstractions, appropriate level of, 311
changing, 40
of classes, 270–271
clever, 26
descriptive, 39–40
of functions, 297
heuristics on, 309–313
importance of, 309–310
intention-revealing, 18–19
length of corresponding to scope, 22–23
long names for long scopes, 312
making unambiguous, 258
problem domain, 27
pronounceable, 21–22
rules for creating, 18–30
searchable, 22–23
shorter generally better than longer, 30
solution domain, 27
with subtle differences, 20
unambiguous, 312
at the wrong level of abstraction, 271
naming, classes, 138
naming conventions, as inferior to structures, 301
navigational methods, in Active Records, 101
near bugs, testing, 314
negative conditionals, avoiding, 302
negatives, 258
nested structures, 46
Newkirk, Jim, 116
newspaper metaphor, 77–78
niladic argument, 40
no preemption, 337
noise
comments, 64–66
scary, 66
words, 21
nomenclature, using standard, 311–312
nonblocking solutions, 327–328
nonconcurrency-related code, 181
noninformative names, 21
nonlocal information, 69–70
nonpublic code, javadocs in, 71
nonstatic methods, preferred to static, 296
nonthreaded code, getting working first, 187
nonthread-safe classes, 328–329
normal flow, 109
null
not passing into methods, 111–112
not returning, 109–110
passed by a caller accidentally, 111
null detection logic, for ArgumentMarshaler, 214
NullPointerException, 110, 111
number-series naming, 21
O
Object Oriented Analysis and Design with Applications, 8
object-oriented design, 15
objects
compared to data structures, 95, 97
compared to data types and procedures, 101
copying read-only, 181
defined, 95
obscured intent, 295
obsolete comments, 286
obvious behavior, 288–289
obvious code, 12
“Once and only once” principle, 289
“ONE SWITCH” rule, 299
one thing, functions doing, 35–36, 302
OO code, 97
OO design, 139
Open Closed Principle (OCP), 15, 38
by checked exceptions, 106
supporting, 149
operand stack, 324
operating systems, threading policies, 188
operators, precedence of, 86
optimistic locking, 327
optimizations, LAZY-EVALUATION as, 157
optimizing, decision making, 167–168
orderings, calculating the possible, 322–323
organization
for change, 147–150
of classes, 136
managing complexity, 139–140
outbound tests, exercising an interface, 118
avoiding, 45
need for disappearing, 45
outputs, arguments as, 45
overhead, incurred by concurrency, 179
overloading, of code with description, 310
P
paperback model, as an academic model, 27
parameters, taken by instructions, 324
parse operation, throwing an exception, 220
partitioning, 250
paths of execution, 321–326
pathways, through critical sections, 188
pattern names, using standard, 175
patterns
of failure, 314
as one kind of standard, 311
performance
of a client/server pair, 318
concurrency improving, 179
of server-based locking, 333
permutations, calculating, 323
pessimistic locking, 327
phraseology, in similar names, 40
physicalizing, a dependency, 299
Plain-Old Java Objects. See POJOs platforms, running threaded code, 188
pleasing code, 7
pluggable thread-based code, 187
POJO system, agility provided by, 168
POJOs (Plain-Old Java Objects)
creating, 187
implementing business logic, 162
separating threaded-aware code, 190
in Spring, 163
writing application domain logic, 166
polyadic argument, 40
polymorphic behavior, of functions, 296
polymorphic changes, 96–97
position markers, 67
positives
as easier to understand, 258
expressing conditionals as, 302
of decisions, 301precision
as the point of all naming, 30
predicates, naming, 25
preemption, breaking, 338
prefixes
for member variables, 24
as useless in today’s environments, 312–313
pre-increment operator, ++, 324, 325, 326
“prequel”, this book as, 15
principle of least surprise, 288–289, 295
principles, of design, 15
PrintPrimes program, translation into Java, 141
private behavior, isolating, 148–149
private functions, 292
private method behavior, 147
problem domain names, 27
procedural code, 97
procedural shape example, 95–96
procedures, compared to objects, 101
process function, repartitioning, 319–320
process method, I/O bound, 319
processes, competing for resources, 184
processor bound, code as, 318
producer consumer execution model, 184
producer threads, 184
production environment, 127–130
productivity, decreased by messy code, 4
professional programmer, 25
professional review, of code, 268
programmers
as authors, 13–14
conundrum faced by, 6
responsibility for messes, 5–6
unprofessional, 5–6
programming
defined, 2
structured, 48–49
programs, getting them to work, 201
pronounceable names, 21–22
protected variables, avoiding, 80
proxies, drawbacks of, 163
public APIs, javadocs in, 59
puns, avoiding, 26–27
PUTFIELD instruction, as atomic, 325
Q
queries, separating from commands, 45–46
R
random jiggling, tests running, 190
range, including end-point dates in, 276
readability
of clean tests, 124
of code, 76
Dave Thomas on, 9
improving using generics, 115
readability perspective, 8
readers
of code, 13–14
continuous, 184
readers-writers execution model, 184
reading
clean code, 8
code from top to bottom, 37
versus writing, 14
reboots, as a lock up solution, 331
recommendations, in this book, 13
redesign, demanded by the team, 5
redundancy, of noise words, 21
redundant comments, 60–62, 272, 275, 286–287
ReentrantLock class, 183
refactored programs, as longer, 146
refactoring
Args, 212
code incrementally, 172
as an iterative process, 265
putting things in to take out, 233
test code, 127
Refactoring (Fowler), 285
renaming, fear of, 30
repeatability, of concurrency bugs, 180
repeatable tests, 132
requirements, specifying, 2
resetId, byte-code generated for, 324–325
resources
bound, 183
processes competing for, 184
threads agreeing on a global ordering of, 338
responsibilities
counting in classes, 136
definition of, 138
identifying, 139
splitting a program into main, 146
return codes, using exceptions instead, 103–105
reuse, 174
risk of change, reducing, 147
robust clear code, writing, 112
rough drafts, writing, 200
runnable interface, 326
run-on expressions, 295
run-on journal entries, 63–64
runtime logic, separating startup from, 154
S
safety mechanisms, overridden, 289
scaling up, 157–161
scary noise, 66
schema, of a class, 194
schools of thought, about clean code, 12–13
scissors rule, in C++, 81
scope(s)
defined by exceptions, 105
dummy, 90
envying, 293
expanding and indenting, 89
hierarchy in a source file, 88
limiting for data, 181
names related to the length of, 22–23, 312
of shared variables, 333
searchable names, 22–23
Second Law, of TDD, 122
sections, within functions, 36
selector arguments, avoiding, 294–295
self validating tests, 132
Semaphore class, 183
semicolon, making visible, 90
“serial number”, SerialDate using, 271
SerialDate class
making it right, 270–284
naming of, 270–271
refactoring, 267–284
SerialDateTests class, 268
serialization, 272
server, threads created by, 319–321
server application, 317–318, 343–344
server code, responsibilities of, 319
server-based locking, 329
as preferred, 332–333
with synchronized methods, 185
“Servlet” model, of Web applications, 178
Servlets, synchronization problems, 182
set functions, moving into appropriate derivatives, 232, 233–235
setArgument, changing, 232–233
setBoolean function, 217
setter methods, injecting dependencies, 157
setup strategy, 155
SetupTeardownIncluder.java listing, 50–52
shape classes, 95–96
shared data, limiting access, 181
shared variables
method updating, 328
reducing the scope of, 333
shotgun approach, hand-coded instrumentation as, 189
shut-down code, 186
shutdowns, graceful, 186
side effects
having none, 44
names describing, 313
Simmons, Robert, 276
Simple Design, rules of, 171–176
single assert rule, 130–131
single concepts, in each test function, 131–132
Single Responsibility Principle (SRP), 15, 138–140
applying, 321
breaking, 155
as a concurrency defense principle, 181
recognizing violations of, 174
server violating, 320
Sql class violating, 147
supporting, 157
in test classes conforming to, 172
violating, 38
single value, ordered components of, 42
single-thread calculation, of throughput, 334
SINGLETON pattern, 274
small classes, 136
Smalltalk Best Practice Patterns, 296
smart programmer, 25
software project, maintenance of, 175
software systems. See also system(s)
compared to physical systems, 158
SOLID class design principle, 150
solution domain names, 27
source code control systems, 64, 68, 69
source files
compared to newspaper articles, 77–78
multiple languages in, 288
Sparkle program, 34
spawned threads, deadlocked, 186
special case objects, 110
SPECIAL CASE PATTERN, 109
specifications, purpose of, 2
spelling errors, correcting, 20
SpreadsheetDateFactory, 274–275
Spring AOP, proxies in, 163
Spring Framework, 157
Spring model, following EJB3, 165
Spring V2.5 configuration file, 163–164
spurious failures, 187
Sql class, changing, 147–149
square root, as the iteration limit, 74
SRP. See Single Responsibility Principle
standard conventions, 299–300
standard nomenclature, 175, 311–312
standards, using wisely, 168
startup process, separating from runtime logic, 154
static function, 279
static import, 308
static methods, inappropriate, 296
The Step-down Rule, 37
stories, implementing only today’s, 158
STRATEGY pattern, 290
string arguments, 194, 208–212, 214–225
string comparison errors, 252
StringBuffers, 129
Stroustrup, Bjarne, 7–8
structure(s). See also data structures
hiding, 99
hybrid, 99
making massive changes to, 212
over convention, 301
structured programming, 48–49
SuperDashboard class, 136–137
swapping, as permutations, 323
switch statements
considering polymorphism before, 299
reasons to tolerate, 38–39
switch/case chain, 290
synchronization problems, avoiding with Servlets, 182
synchronized block, 334
synchronized keyword, 185
adding, 323
always acquiring a lock, 328
introducing a lock via, 331
protecting a critical section in code, 181
synchronized methods, 185
synchronizing, avoiding, 182
synthesis functions, 265
system(s). See also software systems
file sizes of significant, 77
keeping running during development, 213
needing domain-specific, 168
system architecture, test driving, 166–167
system failures, not ignoring one-offs, 187
system level, staying clean at, 154
system-wide information, in a local comment, 69–70
T
tables, moving, 275
target deployment platforms, running tests on, 341
task swapping, encouraging, 188
TDD (Test Driven Development), 213
building logic, 106
as fundamental discipline, 9
laws of, 122–123
team rules, 90
teams
coding standard for every, 299–300
slowed by messy code, 4
technical names, choosing, 27
technical notes, reserving comments for, 286
TEMPLATE METHOD pattern
addressing duplication, 290
removing higher-level duplication, 174–175
using, 130
temporal coupling. See also coupling
exposing, 259–260
hidden, 302–303
side effect creating, 44
temporary variables, explaining, 279–281
test cases
adding to check arguments, 237
in ComparisonCompactor, 252–254
turning off, 58
TEST DOUBLE, assigning, 155
Test Driven Development. See TDD
test driving, architecture, 166–167
test environment, 127–130
test functions, single concepts in, 131–132
test implementation, of an interface, 150
test suite
automated, 213
verifying precise behavior, 146
testable systems, 172
test-driven development. See TDD
testing
arguments making harder, 40
construction logic mixed with runtime, 155
testing language, domain-specific, 127
tests
clean, 124–127
cleanliness tied to, 9
commented out for SerialDate, 268–270
dirty, 123
enabling the -ilities, 124
fast, 132
fast versus slow, 314
heuristics on, 313–314
ignored, 313
independent, 132
insufficient, 313
keeping clean, 123–124
minimizing assert statements in, 130–131
not stopping trivial, 313
refactoring, 126–127
repeatable, 132
requiring more than one step, 287
running, 341
self validating, 132
simple design running all, 172
suite of automated, 213
timely, 133
writing for multithreaded code, 339–342
writing for threaded code, 186–190
writing good, 122–123
Third Law, of TDD, 122
third-party code integrating, 116
learning, 116
using, 114–115
writing tests for, 116
this variable, 324
thread(s)
adding to a method, 322
interfering with each other, 330
making as independent as possible, 182
stepping on each other, 180, 326
taking resources from other threads, 338
thread management strategy, 320
thread pools, 326
thread-based code, testing, 342
threaded code making pluggable, 187
making tunable, 187–188
symptoms of bugs in, 187
testing, 186–190
threading
adding to a client/server application, 319, 346–347
problems in complex systems, 342
thread-safe collections, 182–183, 329
throughput
causing starvation, 184
improving, 319
increasing, 333–335
validating, 318
throws clause, 106
tiger team, 5
tight coupling, 172
time, taking to go fast, 6
Time and Money project, 76
file sizes, 77
timely tests, 133
timer program, testing, 121–122
“TO” keyword, 36
TO paragraphs, 37
TODO comments, 58–59
tokens, used as magic numbers, 300
tools
coverage, 313
handling proxy boilerplate, 163
testing thread-based code, 342
train wrecks, 98–99
transformations, as return values, 41
transitive navigation, avoiding, 306–307
triadic argument, 40
triads, 42
try blocks, 105
try/catch blocks, 46–47, 65–66
try-catch-finally statement, 105–106
tunable threaded-based code, 187–188
type encoding, 24
U
ubiquitous language, 311–312
unambiguous names, 312
unchecked exceptions, 106–107
unencapsulated conditional, encapsulating, 257
unit testing, isolated as difficult, 160
unprofessional programming, 5–6
uppercase C, in variable names, 20
usability, of newspapers, 78
use, of a system, 154
users, handling concurrently, 179
V
validation, of throughput, 318
variable names, single-letter, 25
1 based versus zero based, 261
explaining temporary, 279–281
explanatory, 296–297
keeping private, 93
moving to a different class, 273
in place of comments, 67
promoting to instance variables of classes, 141
with unclear context, 28
venting, in comments, 65
verbs, keywords and, 43
Version class, 139
versions, not deserializing across, 272
vertical density, in code, 79–80
vertical distance, in code, 80–84
vertical formatting, 76–85
vertical openness, between concepts, 78–79
vertical ordering, in code, 84–85
vertical separation, 292
W
wading, through bad code, 3
Web containers, decoupling provided by, 178
what, decoupling from when, 178
white space, use of horizontal, 86
wildcards, 307
Working Effectively with Legacy Code, 10
“working” programs, 201
workmanship, 176
wrappers, 108
wrapping, 108
writers, starvation of, 184
“Writing Shy Code”, 306
X
XML
deployment descriptors, 160
“policy” specified configuration files, 164