IFilter Interface | Apache log4net™ SDK Documentation

Implement this interface to provide customized logging event filtering

Namespace: log4net.Filter
Assembly: log4net (in log4net.dll) Version: 2.0.8.0-.NET 4.0
Syntax

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    public interface IFilter : IOptionHandler

    Public Interface IFilter
    	Inherits IOptionHandler

    public interface class IFilter : IOptionHandler

    type IFilter =
        interface
            interface IOptionHandler
        end

The IFilter type exposes the following members.

Properties

| Name | Description
--- | --- | ---
| Next | Property to get and set the next filter

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Methods

| Name | Description
--- | --- | ---
| ActivateOptions | Activate the options that were previously set with calls to properties. (Inherited from IOptionHandler.)
| Decide | Decide if the logging event should be logged through an appender.

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Remarks

Users should implement this interface to implement customized logging event filtering. Note that Logger and AppenderSkeleton, 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(LoggingEvent) method of each filter is called sequentially, in the order of their addition to the chain.

The Decide(LoggingEvent) method must return one of the integer constants Deny, Neutral or Accept.

If the value Deny is returned, then the log event is dropped immediately without consulting with the remaining filters.

If the value 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 behavior is to log all logging events.

If the value Accept is returned, then the log event is logged without consulting the remaining filters.

The philosophy of log4net filters is largely inspired from the Linux ipchains.

See Also

#### Reference

log4net.Filter Namespace