coupling Comparison Table

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coupling comparison table

Subject avoid by be avoided minimize be cause is a subtopic of have example occur in occur avoid have disadvantage has definition share reduce by name after use by

common coupling creating a module that has specially-designated public methods, which can be called to obtain or modify the system-wide default values hard to assess 9.2 - Principles Leading to Good Design A form of coupling in which components share data using a global variable and thus become dependent on each other many of the disadvantages of content coupling

content coupling hard to assess 9.2 - Principles Leading to Good Design since any modification of data should be easy to find and easy to understand An undesirable form of coupling in which a component surreptitiously modifies internal data of another component

control coupling hard to assess 9.2 - Principles Leading to Good Design
public routineX(String command)
{
//routineX will have to change whenever any of its callers adds a new command
if (command.equals("drawCircle")
{
drawCircle();
}
else
{
drawRectangle();
}
}
when one procedure calls another using a 'flag' or 'command' that explicitly controls what the second procedure does A form of coupling in which one component affects the sequence of execution in another
having the callers of the routine directly call the methods called in the second routine
the use of polymorphic operations
using a look-up table that maps a command to a method that should be called when that command is issued
common blocks in the Fortran language which are used to hold global variables

data coupling always present to some extent 9.2 - Principles Leading to Good Design components become coupled because they are dependent on each other's interpretation of the meaning of the arguments; if that meaning changes in one component, then the other component may have to change to accommodate the new meaning A form of coupling in which one component passes simple data to another as an argument
not passing unnecessary arguments
passing few arguments, each containing more abstract information

external coupling hard to assess 9.2 - Principles Leading to Good Design A form of coupling in which a software component has a dependency to software written by a third party, or to a particular type of hardware
reducing the number of places in the code where such dependencies exist
using the facade pattern

import coupling a weaker form of inclusion coupling a system to suddenly fail if a new item is added to an imported file, and this new item has the same name as something you have already defined in your subsystem 9.2 - Principles Leading to Good Design if the imported component changes something on which the importer relies, or adds something that raises a conflict with something in the importer, then the importer must change A form of coupling in which one component declares that it imports (makes use of the definitions in) another not importing packages or classes which you do not need Java

inclusion coupling a stronger form of import coupling 9.2 - Principles Leading to Good Design if the included component changes something on which the includer relies, or adds something that raises a conflict with something in the includer, then the includer must change A form of coupling in which one component includes the source code of another component. All the includers of a component are coupled to each other and to the included file not including components which you do not need C and C++

low coupling hard to assess 3.2 - Incorporating Reusability and Reuse Into Software Engineering A kind of coupling in which the interconnections among parts of a system are reduced, making makes the resulting application easier to understand, modify and test

routine call coupling always present in an object oriented system 9.2 - Principles Leading to Good Design A form of coupling in which one routine calls another reducing the total number of routines that a particular class or package calls: If you use a sequence of two or more methods to compute something, and this sequence is used in more than one place, then you can reduce routine call coupling by writing a single routine that encapsulates the sequence

stamp coupling hard to assess 9.2 - Principles Leading to Good Design if the shared class changes, then all the classes that access its variables will likely have to change A form of coupling in which two components modify or access data in the same object requiring that all variables of the shared class only be accessible via methods

tight coupling hard to assess a system to be hard to understand and change because
changes in one place will require changes somewhere else. Requiring changes to be made in more than one place is problematic since it is time-consuming to find the different places that need changing, and it is likely that errors will be made
A network of interdependencies makes it hard to see at a glance how some component works
9.2 - Principles Leading to Good Design

type use coupling similar to common coupling, but instead of data being shared, only data types are shared 9.2 - Principles Leading to Good Design typed languages such as Java when a class declares a variable as having another class as its type if the type definition changes, then the users of the type may well have to change. A form of coupling in which several components make use of the same globally-defined data type
ensuring that a class is only type-coupled to classes in a relatively small number of packages
declaring the type of a variable to be the most general possible class or interface that contains the required operations

Next measurement: coverage Up: measurement, software quality Previous measurement: cohesion

Subject	avoid by	be avoided	minimize	be	cause	is a subtopic of	have example	occur in	occur	avoid	have disadvantage	has definition	share	reduce by	name after	use by
common coupling	creating a module that has specially-designated public methods, which can be called to obtain or modify the system-wide default values			hard to assess		9.2 - Principles Leading to Good Design						A form of coupling in which components share data using a global variable and thus become dependent on each other	many of the disadvantages of content coupling
content coupling				hard to assess		9.2 - Principles Leading to Good Design				since any modification of data should be easy to find and easy to understand		An undesirable form of coupling in which a component surreptitiously modifies internal data of another component
control coupling				hard to assess		9.2 - Principles Leading to Good Design	public routineX(String command) { //routineX will have to change whenever any of its callers adds a new command if (command.equals("drawCircle") { drawCircle(); } else { drawRectangle(); } }		when one procedure calls another using a 'flag' or 'command' that explicitly controls what the second procedure does			A form of coupling in which one component affects the sequence of execution in another		having the callers of the routine directly call the methods called in the second routine the use of polymorphic operations using a look-up table that maps a command to a method that should be called when that command is issued	common blocks in the Fortran language which are used to hold global variables
data coupling				always present to some extent		9.2 - Principles Leading to Good Design					components become coupled because they are dependent on each other's interpretation of the meaning of the arguments; if that meaning changes in one component, then the other component may have to change to accommodate the new meaning	A form of coupling in which one component passes simple data to another as an argument		not passing unnecessary arguments passing few arguments, each containing more abstract information
external coupling				hard to assess		9.2 - Principles Leading to Good Design						A form of coupling in which a software component has a dependency to software written by a third party, or to a particular type of hardware		reducing the number of places in the code where such dependencies exist using the facade pattern
import coupling				a weaker form of inclusion coupling	a system to suddenly fail if a new item is added to an imported file, and this new item has the same name as something you have already defined in your subsystem	9.2 - Principles Leading to Good Design					if the imported component changes something on which the importer relies, or adds something that raises a conflict with something in the importer, then the importer must change	A form of coupling in which one component declares that it imports (makes use of the definitions in) another		not importing packages or classes which you do not need		Java
inclusion coupling				a stronger form of import coupling		9.2 - Principles Leading to Good Design					if the included component changes something on which the includer relies, or adds something that raises a conflict with something in the includer, then the includer must change	A form of coupling in which one component includes the source code of another component. All the includers of a component are coupled to each other and to the included file		not including components which you do not need		C and C++
low coupling				hard to assess		3.2 - Incorporating Reusability and Reuse Into Software Engineering						A kind of coupling in which the interconnections among parts of a system are reduced, making makes the resulting application easier to understand, modify and test
routine call coupling				always present in an object oriented system		9.2 - Principles Leading to Good Design						A form of coupling in which one routine calls another		reducing the total number of routines that a particular class or package calls: If you use a sequence of two or more methods to compute something, and this sequence is used in more than one place, then you can reduce routine call coupling by writing a single routine that encapsulates the sequence
stamp coupling				hard to assess		9.2 - Principles Leading to Good Design					if the shared class changes, then all the classes that access its variables will likely have to change	A form of coupling in which two components modify or access data in the same object		requiring that all variables of the shared class only be accessible via methods
tight coupling				hard to assess	a system to be hard to understand and change because changes in one place will require changes somewhere else. Requiring changes to be made in more than one place is problematic since it is time-consuming to find the different places that need changing, and it is likely that errors will be made A network of interdependencies makes it hard to see at a glance how some component works	9.2 - Principles Leading to Good Design
type use coupling				similar to common coupling, but instead of data being shared, only data types are shared		9.2 - Principles Leading to Good Design		typed languages such as Java	when a class declares a variable as having another class as its type		if the type definition changes, then the users of the type may well have to change.	A form of coupling in which several components make use of the same globally-defined data type		ensuring that a class is only type-coupled to classes in a relatively small number of packages declaring the type of a variable to be the most general possible class or interface that contains the required operations