1Agent::Tag(3)         User Contributed Perl Documentation        Agent::Tag(3)
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NAME

6       Log::Agent::Tag - formats caller information
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SYNOPSIS

9        Intended to be inherited from
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DESCRIPTION

12       This class is meant to be inherited by all the classes implementing a
13       log message tag.
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15       A message tag is a little string that is either appended or prepended
16       to all log messages.
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18       For instance, and oversimplifying a bit, a tag meant to be prepended
19       will be inserted in front of the current log message, separated by
20       separator, which defaults to a single space:
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22          +------------+-----------+---------------------------------+
23          | tag string | separator |      current log message        |
24          +------------+-----------+---------------------------------+
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26       This operation is called tag insertion. The whole string then becomes
27       the current log message, and can be the target of another tag
28       insertion.
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30       The reality is a little bit more complex, to allow successive tags to
31       be prepended or appended in the order they are specified, and not in
32       reverse order as they would be if naively implemented.  See
33       Log::Agent::Message for the exact semantics of append() and prepend()
34       operations.
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FEATURES

37       This section documents the interface provided to heirs, in case you
38       wish to implement your own tag class.
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40       _init(name, postfix, separator)
41           Initialization routine that should be called by all heirs during
42           creation to initialize the common attributes.
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44       postfix
45           When true, the tag is meant to be appended to the log message.
46           Otherwise, it is prepended.
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48       name
49           The name of this tag.  It is meant to provide by-name access to
50           tags, check whether a given tag is recorded, etc...  The names
51           "caller" and "priority" are architecturally defined to refer to
52           "Log::Agent::Tag::Caller" and "Log::Agent::Tag::Priority" objects.
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54           NOTE: Currently unused by any client code.
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56       separator
57           The sperating string inserted between the tag and the log message.
58           It defaults to " " if not specified, i.e. left to "undef" when
59           calling _init().
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61       string()
62           A deferred routine, to be implemented by heirs.
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64           Returns the tag string only, without the separator, since its exact
65           placement depends on the value of the "postfix" attribute.
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67       insert(message)
68           Insert this tag withing the "Log::Agent::Message" message,
69           according to the tag specifications (placement, separator).  Calls
70           string() to produce the tag string.
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72           This routine is frozen and should not be redefined by heirs.
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STANDARD TAGGING CLASSES

75       Tagging classes define via their "string()" routine what is the string
76       to be used as a tag.  The insertion of the tag within the log message
77       is done via a frozen routine from the "Log::Agent::Tag" ancestor.
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79       The following classes are provided by "Log::Agent":
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81       "Log::Agent::Tag::Callback"
82           The "string()" routine invokes a user-supplied callback, given as a
83           "Callback" object.  You need the Callback module from CPAN if you
84           wish to use this class.
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86       "Log::Agent::Tag::Caller"
87           Used internally to compute the caller and format it according to
88           user specifications.
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90       "Log::Agent::Tag::Priority"
91           Used internally to format message priorities and add them to the
92           log messages.
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94       "Log::Agent::Tag::String"
95           Defines a constant tagging string that should be added in all the
96           log messages, e.g. a web session ID.
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AUTHOR

99       Raphael Manfredi <Raphael_Manfredi@pobox.com>
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SEE ALSO

102       Log::Agent::Message(3).
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106perl v5.34.0                      2022-01-21                     Agent::Tag(3)
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