log4net SDK Reference |

# FilterSkeleton Class

Subclass this type to implement customized logging event filtering

For a list of all members of this type, see FilterSkeleton Members.

System.Object
log4net.Filter.FilterSkeleton
log4net.Filter.DenyAllFilter
log4net.Filter.LevelMatchFilter
log4net.Filter.LevelRangeFilter
log4net.Filter.LoggerMatchFilter
log4net.Filter.StringMatchFilter

[Visual Basic]
MustInherit Public Class FilterSkeleton
Implements IFilter, IOptionHandler
[C#]
public abstract class FilterSkeleton : IFilter, IOptionHandler

#### Thread Safety

This type is not safe for multithreaded operations.

#### Remarks

Users should extend this class 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 method of each filter is called sequentially, in the order of their addition to the chain.

The Decide 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.

#### Requirements

Namespace: log4net.Filter

Assembly: log4net (in log4net.dll)

#### See Also

FilterSkeleton Members | log4net.Filter Namespace