cohesion

views updated May 23 2018

cohesion (functional cohesion) A measure of the degree to which parts of a program module are closely functionally related. High cohesion means that each part is directed toward and essential for that module to perform its required function, and that the module performs only that function. Low cohesion might be due to convenience grouping of functions that are unrelated by function, timing, logic, procedure, or by sequence.

Temporal cohesion occurs where a module contains several functions that must be performed at the same time, but are not closely related by function.

Logical cohesion is where several logically related functions are placed in the same module. For example a unit may handle all input to a program irrespective of its source being from disk, communications port, keyboard, etc.

Procedural cohesion is where functions that must be performed in a certain order are grouped together in the same module.

Sequential cohesion occurs when the output from one part of a module is the input to the next part, but if the module is not constructed for functional cohesion it is possible that not all the related parts will occur in the one module.

High functional cohesion might be seen as one characteristic of good design. See also coupling.

cohesion

views updated May 08 2018

cohesion Ability of particles to stick together without dependence on interparticle friction. In soils, cohesion is due to the shearing strength of the cement or film of water that separates individual grains. In powder technology, cohesion refers to the forces of attraction by which the particles are held together either by compaction or a binding substance.

cohesion

views updated May 23 2018

cohesion
1. The force of attraction between like molecules. Cohesion provides the force that holds up a column of water in the xylem tissue of plants without it breaking. The cohesion–tension theory is the most widely accepted explanation for the continual flow of water upwards through the xylem of a plant. Water is removed from the plant by the process of transpiration, which creates a tension that pulls the water in the xylem upwards as a single column held together by cohesive forces.

2. (in botany) The union of like parts, such as the fusion of petals that occurs in some flowers.

cohesion

views updated May 23 2018

co·he·sion / kōˈhēzhən/ • n. the action or fact of forming a united whole: the work at present lacks cohesion. ∎  Physics the sticking together of particles of the same substance.

cohesion

views updated May 23 2018

cohesion Mutual attraction between the component atoms, ions or molecules of a substance. Weak cohesive forces permit the fluidity of liquids; those of solids are much stronger. Liquids form droplets because of surface tension caused by cohesion.

cohesion

views updated May 21 2018

cohesion The ability of particles to stick together without dependence on interparticle friction. In soils, cohesion is due to the shearing strength of the cement or film of water that separates individual grains.