Program components having multiple selectable implementations

A computer readable medium readable by a computer and including computer instructions for carrying out a method of minimizing the cost of using a component of a computer program, said method comprising the steps of;

• a) providing said component with a plurality of explicit selectable alternative implementations which share a common component interface and semantics;
• b) instrumenting said component to gather cost-related information during at least a partial run of said program;
• c) providing said component with a cost estimator for using said cost-related information to estimate a cost for using each of said explicitly selectable implementations in running said program;
• d) based on the costs estimated in step (c), selecting one of said explicitly selectable implementations for a subsequent at least partial run of said program.

A computer program comprising a plurality of components which interact during running thereof, at least one of said components comprising:

• a) a plurality of explicit selectable alternative implementations;
• b) a common interface and semantics for receiving messages from an other one of said components and sending messages thereto;
• c) an instrumentation for gathering cost-related information during at least a partial run of said computer program;
• d) a cost estimator for using said cost-related information to estimate a cost for using each of said explicit selectable alternative implementations;
• and
• e) a selector for choosing one of said alternative implementations in response to a message received at said interface from one of an application program and an other one of said components.