Re: [Log4cplus-devel] Header line for file appenders

[Václav Z. <vha...@gm...>]

On 01/29/2014 07:20 PM, Steve Hartmann wrote:
> 
> 
> On 1/29/14 3:38 AM, "Václav Zeman" <vha...@gm...> wrote:
> 
>> It seems to me that layout would be a better place for this.
>>
>> Is there a prior art for this feature in log4j (or any other Java
>> logging library) or log4net, etc.? We could copy their design
>> decisions / interfaces.
>>
> 
> With log4j, you have to extend the layout.  Here is a link to an article
> on how to use it:  
> http://www.coderanch.com/t/535099/oa/Inserting-Header-Text-Log-file
> 
> Personally, I would like to just have it built in as a property - what do
> you think?
> 

Yeah, I do not think that having to derive own layout is the way to go.
It should be built-in. I am not sure if it should be in PatternLayout
(and TTCCLayout) only or if it should be part of the base Layout class;
Adding the header information to a new base class, that would be between
Layout and PatternLayout does not sound wrong to me. I can imagine a
layout without a need for a header (e.g., XMLLayout). But adding it to
the base class would be a lot less intrusive.

(...)

OK, my suggestion is to keep Layout, SimpleLayout and TTCCLayout as they
are, no header. Add a new base class, say, LayoutHeader with virtual
tstring getHeader() const = 0 member function and inherit from this new
base class and implement the pure virtual member function in
PatternLayout. Use dynamic_cast<LayoutHeader *> to test for header
availability in appenders where it makes any sense.

-- 
VZ