org.norecess.citkit.environment
Interface IEnvironment<T>

All Superinterfaces:

java.io.Serializable

All Known Implementing Classes:

Environment, NullEnvironment

public interface IEnvironment<T>
extends java.io.Serializable

Interface for environments. See Environment for a practical implementation. The generic type parameter is the type of the values stored in the environment; the keys must be Symbols.

Author:

Jeremy D. Frens

Method Summary

void	add(ISymbol variable, T value) Adds a new variable to the current environment.
IEnvironment<T>	create() Creates a nested environment.
void	define(ISymbol variable, T value) Defines the variable in the top level environment.
T	get(ISymbol variable) Returns the value associated with the specified variable.
T	set(ISymbol variable, T value) Changes the value associated with the specified variable.

Method Detail

define

void define(ISymbol variable,
            T value)

Defines the variable in the top level environment.

Parameters:

variable - the variable to define.

value - the value to set it to.

add

void add(ISymbol variable,
         T value)
         throws InvalidVariableException

Adds a new variable to the current environment. Presently, this does not check the previous environments to see if this shadows an earlier declaration; if this were implemented, it'd be a warning, not an error.

Parameters:

variable - the new variable to add to the environment.

value - the new value to associate with the new variable.

Throws:

InvalidVariableException - when the variable is already declared in the current scope.

get

T get(ISymbol variable)
      throws InvalidVariableException

Returns the value associated with the specified variable. The variable is searched for in all of the previous scopes.

Parameters:

variable - the variable to search for.

Returns:

the value associated with the variable.

Throws:

InvalidVariableException - when the variable is undeclared (in this or any previous scope).

set

T set(ISymbol variable,
      T value)
      throws InvalidVariableException

Changes the value associated with the specified variable. The variable is searched for in all of the previous scopes; the old value is returned.

Parameters:

variable - the variable to search for.

value - the new value for the variable.

Returns:

the old value associated with the variable.

Throws:

InvalidVariableException - when the variable is undeclared (in this or any previous scope).

create

IEnvironment<T> create()

Creates a nested environment.