Method has too many lines. [24/10] Open
def run
concourse_url = @config[:concourse_url]
concourse_password = @config[:concourse_password]
concourse_username = @config[:concourse_username]
@fly_main.login(url = concourse_url, password = concourse_password)
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This cop checks if the length of a method exceeds some maximum value. Comment lines can optionally be ignored. The maximum allowed length is configurable.
Method has too many lines. [23/10] Open
def parse
options = @options
opt_parser = OptionParser.new do |opts|
opts.banner = "Incomplete/wrong parameter(s): #{opts.default_argv}.\n Usage: ./#{opts.program_name} <options>"
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This cop checks if the length of a method exceeds some maximum value. Comment lines can optionally be ignored. The maximum allowed length is configurable.
Assignment Branch Condition size for parse is too high. [23.96/15] Open
def parse
options = @options
opt_parser = OptionParser.new do |opts|
opts.banner = "Incomplete/wrong parameter(s): #{opts.default_argv}.\n Usage: ./#{opts.program_name} <options>"
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This cop checks that the ABC size of methods is not higher than the configured maximum. The ABC size is based on assignments, branches (method calls), and conditions. See http://c2.com/cgi/wiki?AbcMetric
Assignment Branch Condition size for run is too high. [22.56/15] Open
def run
concourse_url = @config[:concourse_url]
concourse_password = @config[:concourse_password]
concourse_username = @config[:concourse_username]
@fly_main.login(url = concourse_url, password = concourse_password)
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This cop checks that the ABC size of methods is not higher than the configured maximum. The ABC size is based on assignments, branches (method calls), and conditions. See http://c2.com/cgi/wiki?AbcMetric
Method has too many lines. [11/10] Open
def pipelines(env = {})
pipelines = {}
output = fly("pipelines", env)
output.each_line do |line|
matches = line.match /^([\w|-]+)\s+(\w*)\s+(\w*)/
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This cop checks if the length of a method exceeds some maximum value. Comment lines can optionally be ignored. The maximum allowed length is configurable.
CommandLineParser#parse refers to 'options' more than self (maybe move it to another class?) Open
opts.on('-c', '--config URL', "MANDATORY - concourse url. Default: #{options[:concourse_url]}") do |c_string|
options[:concourse_url] = c_string
end
opts.on('-v', '--version VERSION', 'MANDATORY - coa version to switch to v<x.y.z>') do |v_string|
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Feature Envy occurs when a code fragment references another object more often than it references itself, or when several clients do the same series of manipulations on a particular type of object.
Feature Envy reduces the code's ability to communicate intent: code that "belongs" on one class but which is located in another can be hard to find, and may upset the "System of Names" in the host class.
Feature Envy also affects the design's flexibility: A code fragment that is in the wrong class creates couplings that may not be natural within the application's domain, and creates a loss of cohesion in the unwilling host class.
Feature Envy often arises because it must manipulate other objects (usually its arguments) to get them into a useful form, and one force preventing them (the arguments) doing this themselves is that the common knowledge lives outside the arguments, or the arguments are of too basic a type to justify extending that type. Therefore there must be something which 'knows' about the contents or purposes of the arguments. That thing would have to be more than just a basic type, because the basic types are either containers which don't know about their contents, or they are single objects which can't capture their relationship with their fellows of the same type. So, this thing with the extra knowledge should be reified into a class, and the utility method will most likely belong there.
Example
Running Reek on:
class Warehouse
def sale_price(item)
(item.price - item.rebate) * @vat
end
end
would report:
Warehouse#total_price refers to item more than self (FeatureEnvy)
since this:
(item.price - item.rebate)
belongs to the Item class, not the Warehouse.
CommandLineParser#parse has approx 17 statements Open
def parse
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A method with Too Many Statements
is any method that has a large number of lines.
Too Many Statements
warns about any method that has more than 5 statements. Reek's smell detector for Too Many Statements
counts +1 for every simple statement in a method and +1 for every statement within a control structure (if
, else
, case
, when
, for
, while
, until
, begin
, rescue
) but it doesn't count the control structure itself.
So the following method would score +6 in Reek's statement-counting algorithm:
def parse(arg, argv, &error)
if !(val = arg) and (argv.empty? or /\A-/ =~ (val = argv[0]))
return nil, block, nil # +1
end
opt = (val = parse_arg(val, &error))[1] # +2
val = conv_arg(*val) # +3
if opt and !arg
argv.shift # +4
else
val[0] = nil # +5
end
val # +6
end
(You might argue that the two assigments within the first @if@ should count as statements, and that perhaps the nested assignment should count as +2.)
Fly#login has boolean parameter 'insecure' Open
def login(url, team = 'main', username = 'atc', password, insecure: false, env: {})
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Boolean Parameter
is a special case of Control Couple
, where a method parameter is defaulted to true or false. A Boolean Parameter effectively permits a method's caller to decide which execution path to take. This is a case of bad cohesion. You're creating a dependency between methods that is not really necessary, thus increasing coupling.
Example
Given
class Dummy
def hit_the_switch(switch = true)
if switch
puts 'Hitting the switch'
# do other things...
else
puts 'Not hitting the switch'
# do other things...
end
end
end
Reek would emit the following warning:
test.rb -- 3 warnings:
[1]:Dummy#hit_the_switch has boolean parameter 'switch' (BooleanParameter)
[2]:Dummy#hit_the_switch is controlled by argument switch (ControlParameter)
Note that both smells are reported, Boolean Parameter
and Control Parameter
.
Getting rid of the smell
This is highly dependent on your exact architecture, but looking at the example above what you could do is:
- Move everything in the
if
branch into a separate method - Move everything in the
else
branch into a separate method - Get rid of the
hit_the_switch
method alltogether - Make the decision what method to call in the initial caller of
hit_the_switch
Fly#login is controlled by argument 'insecure' Open
options += '--insecure ' if insecure
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Control Parameter
is a special case of Control Couple
Example
A simple example would be the "quoted" parameter in the following method:
def write(quoted)
if quoted
write_quoted @value
else
write_unquoted @value
end
end
Fixing those problems is out of the scope of this document but an easy solution could be to remove the "write" method alltogether and to move the calls to "writequoted" / "writeunquoted" in the initial caller of "write".
Fly#teams refers to 'line' more than self (maybe move it to another class?) Open
teams << line.rstrip unless line.to_s.empty?
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Feature Envy occurs when a code fragment references another object more often than it references itself, or when several clients do the same series of manipulations on a particular type of object.
Feature Envy reduces the code's ability to communicate intent: code that "belongs" on one class but which is located in another can be hard to find, and may upset the "System of Names" in the host class.
Feature Envy also affects the design's flexibility: A code fragment that is in the wrong class creates couplings that may not be natural within the application's domain, and creates a loss of cohesion in the unwilling host class.
Feature Envy often arises because it must manipulate other objects (usually its arguments) to get them into a useful form, and one force preventing them (the arguments) doing this themselves is that the common knowledge lives outside the arguments, or the arguments are of too basic a type to justify extending that type. Therefore there must be something which 'knows' about the contents or purposes of the arguments. That thing would have to be more than just a basic type, because the basic types are either containers which don't know about their contents, or they are single objects which can't capture their relationship with their fellows of the same type. So, this thing with the extra knowledge should be reified into a class, and the utility method will most likely belong there.
Example
Running Reek on:
class Warehouse
def sale_price(item)
(item.price - item.rebate) * @vat
end
end
would report:
Warehouse#total_price refers to item more than self (FeatureEnvy)
since this:
(item.price - item.rebate)
belongs to the Item class, not the Warehouse.
Fly#pipelines refers to 'matches' more than self (maybe move it to another class?) Open
next if matches.nil?
name = matches[1]
paused = matches[2]
public = matches[3]
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Feature Envy occurs when a code fragment references another object more often than it references itself, or when several clients do the same series of manipulations on a particular type of object.
Feature Envy reduces the code's ability to communicate intent: code that "belongs" on one class but which is located in another can be hard to find, and may upset the "System of Names" in the host class.
Feature Envy also affects the design's flexibility: A code fragment that is in the wrong class creates couplings that may not be natural within the application's domain, and creates a loss of cohesion in the unwilling host class.
Feature Envy often arises because it must manipulate other objects (usually its arguments) to get them into a useful form, and one force preventing them (the arguments) doing this themselves is that the common knowledge lives outside the arguments, or the arguments are of too basic a type to justify extending that type. Therefore there must be something which 'knows' about the contents or purposes of the arguments. That thing would have to be more than just a basic type, because the basic types are either containers which don't know about their contents, or they are single objects which can't capture their relationship with their fellows of the same type. So, this thing with the extra knowledge should be reified into a class, and the utility method will most likely belong there.
Example
Running Reek on:
class Warehouse
def sale_price(item)
(item.price - item.rebate) * @vat
end
end
would report:
Warehouse#total_price refers to item more than self (FeatureEnvy)
since this:
(item.price - item.rebate)
belongs to the Item class, not the Warehouse.
Fly#login has 6 parameters Open
def login(url, team = 'main', username = 'atc', password, insecure: false, env: {})
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A Long Parameter List
occurs when a method has a lot of parameters.
Example
Given
class Dummy
def long_list(foo,bar,baz,fling,flung)
puts foo,bar,baz,fling,flung
end
end
Reek would report the following warning:
test.rb -- 1 warning:
[2]:Dummy#long_list has 5 parameters (LongParameterList)
A common solution to this problem would be the introduction of parameter objects.
Fly#pipelines has approx 10 statements Open
def pipelines(env = {})
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A method with Too Many Statements
is any method that has a large number of lines.
Too Many Statements
warns about any method that has more than 5 statements. Reek's smell detector for Too Many Statements
counts +1 for every simple statement in a method and +1 for every statement within a control structure (if
, else
, case
, when
, for
, while
, until
, begin
, rescue
) but it doesn't count the control structure itself.
So the following method would score +6 in Reek's statement-counting algorithm:
def parse(arg, argv, &error)
if !(val = arg) and (argv.empty? or /\A-/ =~ (val = argv[0]))
return nil, block, nil # +1
end
opt = (val = parse_arg(val, &error))[1] # +2
val = conv_arg(*val) # +3
if opt and !arg
argv.shift # +4
else
val[0] = nil # +5
end
val # +6
end
(You might argue that the two assigments within the first @if@ should count as statements, and that perhaps the nested assignment should count as +2.)
CoaVersionUpdate#run has approx 19 statements Open
def run
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A method with Too Many Statements
is any method that has a large number of lines.
Too Many Statements
warns about any method that has more than 5 statements. Reek's smell detector for Too Many Statements
counts +1 for every simple statement in a method and +1 for every statement within a control structure (if
, else
, case
, when
, for
, while
, until
, begin
, rescue
) but it doesn't count the control structure itself.
So the following method would score +6 in Reek's statement-counting algorithm:
def parse(arg, argv, &error)
if !(val = arg) and (argv.empty? or /\A-/ =~ (val = argv[0]))
return nil, block, nil # +1
end
opt = (val = parse_arg(val, &error))[1] # +2
val = conv_arg(*val) # +3
if opt and !arg
argv.shift # +4
else
val[0] = nil # +5
end
val # +6
end
(You might argue that the two assigments within the first @if@ should count as statements, and that perhaps the nested assignment should count as +2.)
Method run
has a Cognitive Complexity of 8 (exceeds 5 allowed). Consider refactoring. Open
def run
concourse_url = @config[:concourse_url]
concourse_password = @config[:concourse_password]
concourse_username = @config[:concourse_username]
@fly_main.login(url = concourse_url, password = concourse_password)
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Cognitive Complexity
Cognitive Complexity is a measure of how difficult a unit of code is to intuitively understand. Unlike Cyclomatic Complexity, which determines how difficult your code will be to test, Cognitive Complexity tells you how difficult your code will be to read and comprehend.
A method's cognitive complexity is based on a few simple rules:
- Code is not considered more complex when it uses shorthand that the language provides for collapsing multiple statements into one
- Code is considered more complex for each "break in the linear flow of the code"
- Code is considered more complex when "flow breaking structures are nested"
Further reading
FlyError has no descriptive comment Open
class FlyError < RuntimeError; end
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Classes and modules are the units of reuse and release. It is therefore considered good practice to annotate every class and module with a brief comment outlining its responsibilities.
Example
Given
class Dummy
# Do things...
end
Reek would emit the following warning:
test.rb -- 1 warning:
[1]:Dummy has no descriptive comment (IrresponsibleModule)
Fixing this is simple - just an explaining comment:
# The Dummy class is responsible for ...
class Dummy
# Do things...
end
CoaVersionUpdate has no descriptive comment Open
class CoaVersionUpdate
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Classes and modules are the units of reuse and release. It is therefore considered good practice to annotate every class and module with a brief comment outlining its responsibilities.
Example
Given
class Dummy
# Do things...
end
Reek would emit the following warning:
test.rb -- 1 warning:
[1]:Dummy has no descriptive comment (IrresponsibleModule)
Fixing this is simple - just an explaining comment:
# The Dummy class is responsible for ...
class Dummy
# Do things...
end
CommandLineParser has no descriptive comment Open
class CommandLineParser
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Classes and modules are the units of reuse and release. It is therefore considered good practice to annotate every class and module with a brief comment outlining its responsibilities.
Example
Given
class Dummy
# Do things...
end
Reek would emit the following warning:
test.rb -- 1 warning:
[1]:Dummy has no descriptive comment (IrresponsibleModule)
Fixing this is simple - just an explaining comment:
# The Dummy class is responsible for ...
class Dummy
# Do things...
end
Fly has no descriptive comment Open
class Fly
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Classes and modules are the units of reuse and release. It is therefore considered good practice to annotate every class and module with a brief comment outlining its responsibilities.
Example
Given
class Dummy
# Do things...
end
Reek would emit the following warning:
test.rb -- 1 warning:
[1]:Dummy has no descriptive comment (IrresponsibleModule)
Fixing this is simple - just an explaining comment:
# The Dummy class is responsible for ...
class Dummy
# Do things...
end
Avoid parameter lists longer than 5 parameters. [6/5] Open
def login(url, team = 'main', username = 'atc', password, insecure: false, env: {})
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This cop checks for methods with too many parameters. The maximum number of parameters is configurable. Keyword arguments can optionally be excluded from the total count.
Fly#pipelines performs a nil-check Open
next if matches.nil?
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A NilCheck
is a type check. Failures of NilCheck
violate the "tell, don't ask" principle.
Additionally, type checks often mask bigger problems in your source code like not using OOP and / or polymorphism when you should.
Example
Given
class Klass
def nil_checker(argument)
if argument.nil?
puts "argument isn't nil!"
end
end
end
Reek would emit the following warning:
test.rb -- 1 warning:
[3]:Klass#nil_checker performs a nil-check. (NilCheck)
CoaVersionUpdate#run has the variable name 'e' Open
rescue FlyError => e
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An Uncommunicative Variable Name
is a variable name that doesn't communicate its intent well enough.
Poor names make it hard for the reader to build a mental picture of what's going on in the code. They can also be mis-interpreted; and they hurt the flow of reading, because the reader must slow down to interpret the names.
Fly#fly has the variable name 'k' Open
env_var = env.collect { |k, v| "#{k}=#{v}" }.join(' ')
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An Uncommunicative Variable Name
is a variable name that doesn't communicate its intent well enough.
Poor names make it hard for the reader to build a mental picture of what's going on in the code. They can also be mis-interpreted; and they hurt the flow of reading, because the reader must slow down to interpret the names.
Fly#fly has the variable name 'v' Open
env_var = env.collect { |k, v| "#{k}=#{v}" }.join(' ')
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An Uncommunicative Variable Name
is a variable name that doesn't communicate its intent well enough.
Poor names make it hard for the reader to build a mental picture of what's going on in the code. They can also be mis-interpreted; and they hurt the flow of reading, because the reader must slow down to interpret the names.
Use match?
instead of =~
when MatchData
is not used. Open
options[:coa_version] = v_string if v_string =~ /v\d{1,2}\.\d{1,2}\.\d{1,2}/
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In Ruby 2.4, String#match?
, Regexp#match?
and Symbol#match?
have been added. The methods are faster than match
.
Because the methods avoid creating a MatchData
object or saving
backref.
So, when MatchData
is not used, use match?
instead of match
.
Example:
# bad
def foo
if x =~ /re/
do_something
end
end
# bad
def foo
if x.match(/re/)
do_something
end
end
# bad
def foo
if /re/ === x
do_something
end
end
# good
def foo
if x.match?(/re/)
do_something
end
end
# good
def foo
if x =~ /re/
do_something(Regexp.last_match)
end
end
# good
def foo
if x.match(/re/)
do_something($~)
end
end
# good
def foo
if /re/ === x
do_something($~)
end
end
Use match?
instead of =~
when MatchData
is not used. Open
raise e unless e.message =~ /resource 'cf-ops-automation' not found/
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In Ruby 2.4, String#match?
, Regexp#match?
and Symbol#match?
have been added. The methods are faster than match
.
Because the methods avoid creating a MatchData
object or saving
backref.
So, when MatchData
is not used, use match?
instead of match
.
Example:
# bad
def foo
if x =~ /re/
do_something
end
end
# bad
def foo
if x.match(/re/)
do_something
end
end
# bad
def foo
if /re/ === x
do_something
end
end
# good
def foo
if x.match?(/re/)
do_something
end
end
# good
def foo
if x =~ /re/
do_something(Regexp.last_match)
end
end
# good
def foo
if x.match(/re/)
do_something($~)
end
end
# good
def foo
if /re/ === x
do_something($~)
end
end
Use each_key
instead of each
. Open
pipelines.each do |name, _|
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This cop checks for uses of each_key
and each_value
Hash methods.
Note: If you have an array of two-element arrays, you can put parentheses around the block arguments to indicate that you're not working with a hash, and suppress RuboCop offenses.
Example:
# bad
hash.keys.each { |k| p k }
hash.values.each { |v| p v }
hash.each { |k, _v| p k }
hash.each { |_k, v| p v }
# good
hash.each_key { |k| p k }
hash.each_value { |v| p v }
Optional arguments should appear at the end of the argument list. Open
def login(url, team = 'main', username = 'atc', password, insecure: false, env: {})
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This cop checks for optional arguments to methods that do not come at the end of the argument list
Example:
# bad
def foo(a = 1, b, c)
end
# good
def baz(a, b, c = 1)
end
def foobar(a = 1, b = 2, c = 3)
end
Optional arguments should appear at the end of the argument list. Open
def login(url, team = 'main', username = 'atc', password, insecure: false, env: {})
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This cop checks for optional arguments to methods that do not come at the end of the argument list
Example:
# bad
def foo(a = 1, b, c)
end
# good
def baz(a, b, c = 1)
end
def foobar(a = 1, b = 2, c = 3)
end
Place the end statement of a multi-line method on its own line. Open
class FlyError < RuntimeError; end
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This cop checks for trailing code after the method definition.
Example:
# bad
def some_method
do_stuff; end
def do_this(x)
baz.map { |b| b.this(x) } end
def foo
block do
bar
end end
# good
def some_method
do_stuff
end
def do_this(x)
baz.map { |b| b.this(x) }
end
def foo
block do
bar
end
end
Ambiguous regexp literal. Parenthesize the method arguments if it's surely a regexp literal, or add a whitespace to the right of the /
if it should be a division. Open
matches = line.match /^([\w|-]+)\s+(\w*)\s+(\w*)/
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This cop checks for ambiguous regexp literals in the first argument of a method invocation without parentheses.
Example:
# bad
# This is interpreted as a method invocation with a regexp literal,
# but it could possibly be `/` method invocations.
# (i.e. `do_something./(pattern)./(i)`)
do_something /pattern/i
Example:
# good
# With parentheses, there's no ambiguity.
do_something(/pattern/i)
Useless assignment to variable - password
. Open
@fly_main.login(url = concourse_url, password = concourse_password)
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This cop checks for every useless assignment to local variable in every
scope.
The basic idea for this cop was from the warning of ruby -cw
:
assigned but unused variable - foo
Currently this cop has advanced logic that detects unreferenced reassignments and properly handles varied cases such as branch, loop, rescue, ensure, etc.
Example:
# bad
def some_method
some_var = 1
do_something
end
Example:
# good
def some_method
some_var = 1
do_something(some_var)
end
Useless assignment to variable - url
. Open
@fly_main.login(url = concourse_url, password = concourse_password)
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This cop checks for every useless assignment to local variable in every
scope.
The basic idea for this cop was from the warning of ruby -cw
:
assigned but unused variable - foo
Currently this cop has advanced logic that detects unreferenced reassignments and properly handles varied cases such as branch, loop, rescue, ensure, etc.
Example:
# bad
def some_method
some_var = 1
do_something
end
Example:
# good
def some_method
some_var = 1
do_something(some_var)
end