# Class LoggerFilter

Users should extend this class to implement customized logging event filtering. Note that LoggerCategory and `LoggerAppender`, the parent class of all standard appenders, have built-in filtering rules. It is suggested that you first use and understand the built-in rules before rushing to write your own custom filters.

This abstract class assumes and also imposes that filters be organized in a linear chain. The #decide decide(LoggerLoggingEvent) method of each filter is called sequentially, in the order of their addition to the chain.

The `LoggerFilter::decide()` method must return one of the integer constants `LoggerFilter::DENY`, `LoggerFilter::NEUTRAL` or `LoggerFilter::ACCEPT`.

If the value `LoggerFilter::DENY` is returned, then the log event is dropped immediately without consulting with the remaining filters.

If the value `LoggerFilter::NEUTRAL` is returned, then the next filter in the chain is consulted. If there are no more filters in the chain, then the log event is logged. Thus, in the presence of no filters, the default behaviour is to log all logging events.

If the value `LoggerFilter::ACCEPT` is returned, then the log event is logged without consulting the remaining filters.

The philosophy of log4php filters is largely inspired from the Linux ipchains.

  LoggerConfigurable
  LoggerFilter

#### Direct known subclasses

LoggerFilterDenyAll, LoggerFilterLevelMatch, LoggerFilterLevelRange, LoggerFilterStringMatch
Abstract
Package: log4php
Version: $Revision: 1213283 $
Located at LoggerFilter.php

Methods summary
`public` | # `activateOptions( )` Usually filters options become active when set. We provide a default do-nothing implementation for convenience. Usually filters options become active when set. We provide a default do-nothing implementation for convenience.
`public integer` | # `decide( `LoggerLoggingEvent` $event )` Decide what to do. If the decision is `LoggerFilter::DENY`, then the event will be dropped. If the decision is `LoggerFilter::NEUTRAL`, then the next filter, if any, will be invoked. If the decision is `LoggerFilter::ACCEPT` then the event will be logged without consulting with other filters in the chain.
Decide what to do.

If the decision is `LoggerFilter::DENY`, then the event will be dropped. If the decision is `LoggerFilter::NEUTRAL`, then the next filter, if any, will be invoked. If the decision is `LoggerFilter::ACCEPT` then the event will be logged without consulting with other filters in the chain.

#### Parameters

$event
  ``LoggerLoggingEvent``
  $event The `LoggerLoggingEvent` to decide upon.

#### Returns

`integer`
`LoggerFilter::NEUTRAL` or `LoggerFilter::DENY`|`LoggerFilter::ACCEPT`
`public` | # `addNext( mixed $filter )` Adds a new filter to the filter chain this filter is a part of. If this filter has already and follow up filter, the param filter is passed on until it is the last filter in chain. Adds a new filter to the filter chain this filter is a part of. If this filter has already and follow up filter, the param filter is passed on until it is the last filter in chain.

#### Parameters

$filter
  `mixed`
  $filter - the filter to add to this chain

`public the` | # `getNext( )` Returns the next filter in this chain Returns the next filter in this chain

#### Returns

`the`
next filter

Methods inherited from LoggerConfigurable
`setBoolean(), setFileSize(), setInteger(), setLevel(), setNumeric(), setPositiveInteger(), setString(), warn()`

Constants summary
`integer` | `ACCEPT` | `1` | # The log event must be logged immediately without consulting with the remaining filters, if any, in the chain. The log event must be logged immediately without consulting with the remaining filters, if any, in the chain.
`integer` | `NEUTRAL` | `0` | # This filter is neutral with respect to the log event. The remaining filters, if any, should be consulted for a final decision. This filter is neutral with respect to the log event. The remaining filters, if any, should be consulted for a final decision.
`integer` | `DENY` | `-1` | # The log event must be dropped immediately without consulting with the remaining filters, if any, in the chain. The log event must be dropped immediately without consulting with the remaining filters, if any, in the chain.

Properties summary
`protected `LoggerFilter`` | $next | `` | # Points to the next `LoggerFilter` in the filter chain. Points to the next `LoggerFilter` in the filter chain.