NAME
::log - Procedures to log messages of libraries and appli
cations.
SYNOPSIS
package require log ?1.0?
::log::levels
::log::lv2longform level
::log::lv2color level
::log::lv2priority level
::log::lv2cmd level
::log::lv2channel level
::log::lvCompare level1 level2
::log::lvSuppress level {suppress 1}
::log::lvSuppressLE level {suppress 1}
::log::lvIsSuppressed level
::log::lvCmd level cmd
::log::lvCmdForall cmd
::log::lvChannel level chan
::log::lvChannelForall chan
::log::lvColor level color
::log::lvColorForall color
::log::log level text
::log::logMsg text
::log::logError text
::log::Puts level text
_________________________________________________________________
DESCRIPTION
The ::log package provides commands that allow libraries
and applications to selectively log information about
Each message given to the log facility is associated with
a level determining the importance of the message. The
user can then select which levels to log, what commands to
use for the logging of each level and the channel to write
the message to. The latter is relevant only if the stan
dard command (::log::Puts) to log messages provided by
::log is used. Apprehending the usage of this facility in
graphical applications, i.e. tk-based ones, it also allows
the user to associate colors with the message levels.
The following commands are available:
::log::levels
Returns the names of all known levels, in alphabet
ical order.
::log::lv2longform level
Converts any unique abbreviation of a level name to
the full level name.
::log::lv2color level
Converts any level name including unique abbrevia
tions to the corresponding color.
::log::lv2priority level
Converts any level name including unique abbrevia
tions to the corresponding priority.
::log::lv2cmd level
Converts any level name including unique abbrevia
tions to the command prefix used to write messages
with that level.
::log::lv2channel level
Converts any level name including unique abbrevia
tions to the channel used by ::log::Puts to write
messages with that level.
::log::lvCompare level1 level2
Compares two levels (including unique abbrevia
tions) with respect to their priority. This command
can be used by the -command option of lsort. The
result is one of -1, 0 or 1 or an error. A result
of -1 signals that level1 is of less priority than
level2. 0 signals that both levels have the same
priority. 1 signals that level1 has higher priority
than level2.
::log::lvSuppress level {suppress 1}
(Un)suppresses the output of messages having the
specified level. Unique abbreviations for the level
are allowed here too.
(Un)suppresses the output of messages having the
specified level or one of lesser priority. Unique
abbreviations for the level are allowed here too.
::log::lvIsSuppressed level
Asks the package whether the specified level is
currently suppressed. Unique abbreviations of level
names are allowed.
::log::lvCmd level cmd
Defines for the specified level with which command
to write the messages having this level. Unique
abbreviations of level names are allowed. The com
mand is actually a command prefix and this facility
will append 2 arguments before calling it, the
level of the message and the message itself, in
this order.
::log::lvCmdForall cmd
Defines for all known levels with which command to
write the messages having this level. The command
is actually a command prefix and this facility will
append 2 arguments before calling it, the level of
the message and the message itself, in this order.
::log::lvChannel level chan
Defines for the specified level into which channel
::log::Puts (the standard command) shall write the
messages having this level. Unique abbreviations of
level names are allowed. The command is actually a
command prefix and this facility will append 2
arguments before calling it, the level of the mes
sage and the message itself, in this order.
::log::lvChannelForall chan
Defines for all known levels with which which chan
nel ::log::Puts (the standard command) shall write
the messages having this level. The command is
actually a command prefix and this facility will
append 2 arguments before calling it, the level of
the message and the message itself, in this order.
::log::lvColor level color
Defines for the specified level the color to return
for it in a call to ::log::lv2color. Unique abbre
viations of level names are allowed.
::log::lvColorForall color
Defines for all known levels the color to return
for it in a call to ::log::lv2color. Unique abbre
viations of level names are allowed.
Log a message according to the specifications for
commands, channels and suppression. In other words:
The command will do nothing if the specified level
is suppressed. If it is not suppressed the actual
logging is delegated to the specified command. If
there is no command specified for the level the
message won't be logged. The standard command
::log::Puts will write the message to the channel
specified for the given level. If no channel is
specified for the level the message won't be
logged. Unique abbreviations of level names are
allowed. Errors in the actual logging command are
not caught, but propagated to the caller, as they
may indicate misconfigurations of the log facility
or errors in the callers code itself.
::log::logMsg text
Convenience wrapper around ::log::log. Equivalent
to ::log::log info text.
::log::logError text
Convenience wrapper around ::log::log. Equivalent
to ::log::log error text.
::log::Puts level text
The standard log command, it writes messages and
their levels to user-specified channels. Assumes
that the suppression checks were done by the
caller. Expects full level names, abbreviations are
not allowed.
SEE ALSO
KEYWORDS
log, log level, message level, message
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