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Manual Reference Pages  -  LOG::AGENT::TAG::CALLER (3)

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Log::Agent::Tag::Caller - formats caller information



 Not intended to be used directly
 Inherits from Log::Agent::Tag.


This class handles caller information for Log::Agent services and is not meant to be used directly.

This manpage therefore only documents the creation routine parameters that can be specified at the Log::Agent level via the -caller switch in the logconfig() routine.


This class knows about four entities: package, filename, line and subroutine, which are to be understood within the context of the Log::Agent routine being called (e.g. a logwarn() routine), namely:
package This is the package name where the call to the logwarn() routine was made. It can be specified as pack for short, or spelled out completely.
filename This is the file where the call to the logwarn() routine was made. It can be specified as file for short, or spelled out completely.
line This is the line number where the call to the logwarn() routine was made, in file filename. The name is short enough to be spelled out completely.
subroutine This is the subroutine where the call to the logwarn() routine was made. If the call is made outside a subroutine, this will be empty. The name is long enough to warrant the sub abbreviation if you don’t wish to spell it out fully.


The purpose of those parameters is to define how caller information entities (as defined by the previous section) will be formatted within the log message.
-display => string Specifies a string with minimal variable substitution: only the caller information entities specified above, or their abbreviation, will be interpolated. For instance:

    -display => ($package::$sub/$line)

Don’t forget to use simple quotes to avoid having Perl interpolate those as variables, or escape their leading $ sign otherwise. Using this convention was deemed to more readable (and natural in Perl) than SGML entities such as &pack;.

Using this switch supersedes the -info and -format switches.

-format => printf format Formatting instructions for the caller information entities listed by the -info switch. For instance:

    -format => "%s:%4d"

if you have specified two entities in -info.

The special formatting macro %a stands for all the entities specified by -info and is rendered by a string where values are separated by :.

-info => ‘‘space separated list of parameters’’ Specifies a list of caller information entities that are to be formated using the -format specification. For instance:

    -info => "pack sub line"

would only report those three entites.

-postfix => flag Whether the string resulting from the formatting of the caller information entities should be appended to the regular log message or not (i.e. prepended, which is the default).
-separator => string The separation string between the tag and the log message. A single space by default.


Raphael Manfredi <> created the module, it is currently maintained by Mark Rogaski <>.

Thanks to Jeff Boes for uncovering wackiness in caller().


Copyright (C) 1999 Raphael Manfredi. Copyright (C) 2002 Mark Rogaski; all rights reserved.

See Log::Agent(3) or the README file included with the distribution for license information.


Log::Agent(3), Log::Agent::Message(3).
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perl v5.20.3 AGENT::TAG::CALLER (3) 2015-11-30

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