org.apache.tapestry5.services.EnvironmentalAccess Maven / Gradle / Ivy

Show more of this group Show more artifacts with this name
Show all versions of tapestry-core Show documentation

Central module for Tapestry, containing interfaces to the Java Servlet API and all core services and components.

There is a newer version: 5.8.6

// Copyright 2008 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package org.apache.tapestry5.services;

/**
 * Provides efficient, cached access to an environmental object.
 *
 * @param 
 * @see org.apache.tapestry5.services.Environment#getAccess(Class)
 * @since 5.0.19
 * @deprecated No longer gives a performance advantage due to pool-less pages
 */
public interface EnvironmentalAccess
{

    /**
     * Peeks at the current top of the configured type's stack.
     *
     * @return current value of type, or null.
     */
    T peek();

    /**
     * Peeks at the current top of the configured type's stack.
     *
     * @return the current value
     * @throws RuntimeException if no environmental of that type has been added
     */
    T peekRequired();
}