Method visit_Arel_Nodes_Equality
has a Cognitive Complexity of 9 (exceeds 5 allowed). Consider refactoring. Open
def visit_Arel_Nodes_Equality(o, collector)
case (left = o.left)
when Arel::Attributes::Attribute
table = left.relation.table_name
schema_cache = @connection.schema_cache
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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
Arel::Visitors#visit_Arel_Nodes_Matches refers to 'o' more than self (maybe move it to another class?) Invalid
if !o.case_sensitive && o.left && o.right
o.left = Arel::Nodes::NamedFunction.new('UPPER', [o.left])
o.right = Arel::Nodes::NamedFunction.new('UPPER', [o.right])
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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.
Arel::Visitors#visit_Arel_Nodes_Equality has approx 10 statements Open
def visit_Arel_Nodes_Equality(o, collector)
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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.)
Arel::Visitors#visit_Arel_Nodes_Matches calls 'o.left' 2 times Open
if !o.case_sensitive && o.left && o.right
o.left = Arel::Nodes::NamedFunction.new('UPPER', [o.left])
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Duplication occurs when two fragments of code look nearly identical, or when two fragments of code have nearly identical effects at some conceptual level.
Reek implements a check for Duplicate Method Call.
Example
Here's a very much simplified and contrived example. The following method will report a warning:
def double_thing()
@other.thing + @other.thing
end
One quick approach to silence Reek would be to refactor the code thus:
def double_thing()
thing = @other.thing
thing + thing
end
A slightly different approach would be to replace all calls of double_thing
by calls to @other.double_thing
:
class Other
def double_thing()
thing + thing
end
end
The approach you take will depend on balancing other factors in your code.
Arel::Visitors#visit_Arel_Nodes_Matches calls 'o.right' 2 times Open
if !o.case_sensitive && o.left && o.right
o.left = Arel::Nodes::NamedFunction.new('UPPER', [o.left])
o.right = Arel::Nodes::NamedFunction.new('UPPER', [o.right])
- Read upRead up
- Exclude checks
Duplication occurs when two fragments of code look nearly identical, or when two fragments of code have nearly identical effects at some conceptual level.
Reek implements a check for Duplicate Method Call.
Example
Here's a very much simplified and contrived example. The following method will report a warning:
def double_thing()
@other.thing + @other.thing
end
One quick approach to silence Reek would be to refactor the code thus:
def double_thing()
thing = @other.thing
thing + thing
end
A slightly different approach would be to replace all calls of double_thing
by calls to @other.double_thing
:
class Other
def double_thing()
thing + thing
end
end
The approach you take will depend on balancing other factors in your code.
Arel::Visitors takes parameters ['collector', 'o'] to 4 methods Open
def visit_Arel_Nodes_In(o, collector)
strip_order_from_select(o)
super
end
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In general, a Data Clump
occurs when the same two or three items frequently appear together in classes and parameter lists, or when a group of instance variable names start or end with similar substrings.
The recurrence of the items often means there is duplicate code spread around to handle them. There may be an abstraction missing from the code, making the system harder to understand.
Example
Given
class Dummy
def x(y1,y2); end
def y(y1,y2); end
def z(y1,y2); end
end
Reek would emit the following warning:
test.rb -- 1 warning:
[2, 3, 4]:Dummy takes parameters [y1, y2] to 3 methods (DataClump)
A possible way to fix this problem (quoting from Martin Fowler):
The first step is to replace data clumps with objects and use the objects whenever you see them. An immediate benefit is that you'll shrink some parameter lists. The interesting stuff happens as you begin to look for behavior to move into the new objects.
Arel::Visitors#strip_order_from_select doesn't depend on instance state (maybe move it to another class?) Open
def strip_order_from_select(o)
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A Utility Function is any instance method that has no dependency on the state of the instance.
Arel::Visitors#visit_Arel_Nodes_NotIn has the parameter name 'o' Open
def visit_Arel_Nodes_NotIn(o, collector)
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An Uncommunicative Parameter Name
is a parameter 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.
Arel::Visitors#visit_Arel_Nodes_Equality has the parameter name 'o' Open
def visit_Arel_Nodes_Equality(o, collector)
- Read upRead up
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An Uncommunicative Parameter Name
is a parameter 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.
Arel::Visitors#strip_order_from_select has the parameter name 'o' Open
def strip_order_from_select(o)
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An Uncommunicative Parameter Name
is a parameter 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.
Arel::Visitors#visit_Arel_Nodes_Equality has the name 'visit_Arel_Nodes_Equality' Open
def visit_Arel_Nodes_Equality(o, collector)
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An Uncommunicative Method Name
is a method 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.
Arel::Visitors#visit_Arel_Nodes_In has the parameter name 'o' Open
def visit_Arel_Nodes_In(o, collector)
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An Uncommunicative Parameter Name
is a parameter 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.
Arel::Visitors#visit_Arel_Nodes_Matches has the parameter name 'o' Invalid
def visit_Arel_Nodes_Matches o, collector
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An Uncommunicative Parameter Name
is a parameter 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.
Arel::Visitors#visit_Arel_Nodes_NotIn has the name 'visit_Arel_Nodes_NotIn' Open
def visit_Arel_Nodes_NotIn(o, collector)
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An Uncommunicative Method Name
is a method 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.
Arel::Visitors#visit_Arel_Nodes_In has the name 'visit_Arel_Nodes_In' Open
def visit_Arel_Nodes_In(o, collector)
- Read upRead up
- Exclude checks
An Uncommunicative Method Name
is a method 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.
Arel::Visitors#visit_Arel_Nodes_Matches has the name 'visit_Arel_Nodes_Matches' Invalid
def visit_Arel_Nodes_Matches o, collector
- Read upRead up
- Exclude checks
An Uncommunicative Method Name
is a method 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.