opendap.servers

Interface BTFunction

All Superinterfaces:

ServerSideFunction

public interface BTFunction
extends ServerSideFunction

Represents a server-side function, which evaluates to a BaseType. Custom server-side functions which return non-boolean values should implement this interface. For an efficient implementation, it is suggested, when possible, to use the same BaseType for the getType() method and for each successive invocation of evaluate(), changing only the BaseType's value. This avoids creation of large numbers of BaseTypes during a data request.

Author:

joew

See Also:

BTFunctionClause

Method Summary

Methods

Modifier and Type	Method and Description
BaseType	evaluate(List args) Evaluates the function using the argument list given.
BaseType	getReturnType(List args) A given function must always evaluate to the same class of BaseType.

Methods inherited from interface opendap.servers.ServerSideFunction

checkArgs, getName

Method Detail

getReturnType

BaseType getReturnType(List args)
                       throws InvalidParameterException

A given function must always evaluate to the same class of BaseType. Only the value held by the BaseType may change. This method can be used to discover the BaseType class of a function without actually evaluating it.

Throws:

InvalidParameterException

evaluate

BaseType evaluate(List args)
                  throws DAP2ServerSideException

Evaluates the function using the argument list given.

Throws:

DAP2ServerSideException - Thrown if the function cannot evaluate successfully. The exact type of exception is up to the author of the server-side function.