NAME
Tell - Print messages with balance, indentation, severity, and autoclosure.
*** This documentation is not yet complete ***
*** I'd like to move this into another namespace, ***
*** perhaps Term::Tell or Msg::Tell. Suggestions? ***VERSION
This document describes Tell version 0.0.5
SYNOPSIS
For a script like this:
use Tell qw/:all/;
tell "System parameter updates";
tell "CLOCK_UTC";
#...do_something();
tell_ok;
tell "NTP Servers";
#...do_something();
tell_error;
tell "DNS Servers";
#...do_something();
tell_warn;You get this output:
System parameter updates...
CLOCK_UTC........................................................ [OK]
NTP Servers...................................................... [ERROR]
DNS Servers...................................................... [WARN]
System parameter updates........................................... [DONE]DESCRIPTION
The Tell package is used to print balanced and nested messages with a completion status. These messages indent easily within each other, autocomplete on scope exit, are easily parsed, may be bulleted, can be filtered, and even can show status in color.
For example, you write code like this:
use Tell qw/:all/;
tell "Reconfiguring the grappolator";
do_whatchamacallit();
do_something_else();It begins by printing:
Reconfiguring the grappolator...Then it does "whatchamacallit" and "something else". When these are complete it adds the rest of the line: a bunch of dots and the [DONE].
Reconfiguring the grappolator...................................... [DONE]Your do_whatchamacallit() and do_something_else() subroutines may also tell what they're doing, and indicate success or failure or whatever, so you can get nice output like this:
Reconfiguring the grappolator...
Processing whatchamacallit....................................... [WARN]
Fibulating something else...
Fibulation phase one........................................... [OK]
Fibulation phase two........................................... [ERROR]
Wrapup of fibulation........................................... [OK]
Reconfiguring the grappolator...................................... [DONE]Quick Start
A series of examples will make Tell easier to understand.
Basics
use Tell ':all';
tell "Frobnicating the biffolator";
sleep 1; # simulate the frobnication process
tell_done;First this prints:
Frobnicating the biffolator...Then after the "frobnication" process is complete, the line is continued so it looks like this:
Frobnicating the biffolator....................................... [DONE]Autocompletion
In the above example, we end with a tell_done call to indicate that the thing we told about (Frobnicating the biffolator) is now done. We don't need to do the tell_done. It will be called automatically for us when the current scope is exited (for this example: when the program ends). So the code example could be just this:
use Tell ':all';
tell "Frobnicating the biffolator";
sleep 1; # simulate the frobnication processand we'd get the same results.
Yeah, autocompletion may not seem so useful YET, but hang in there and you'll soon see how wonderful it is.
Completion Severity
There's many ways a task can complete. It can be simply DONE, or it can complete with an ERROR, or it can be OK, etc. These completion codes are called the severity codes. Tell defines many different severity codes. The severity codes are borrowed from the UNIX syslog subsystem, plus a few from VMS and other sources. They should be familiar to you.
Most severity codes also have an associated numerical value. This value is called the severity level. It's useful for comparing severities to eachother or filtering out severities you don't want to be bothered with.
Here are the severity codes and their severity values. Those on the same line are considered equal in severity:
EMERG => 15,
ALERT => 13,
CRIT => 11, FAIL => 11, FATAL => 11,
ERROR => 9,
WARN => 7,
NOTE => 6,
INFO => 5, OK => 5,
DEBUG => 4,
NOTRY => 3,
UNK => 2,You may make up your own severities if what you want is not listed. Please keep the length to 5 characters or less, otherwise the text may wrap. Any severity not listed is given the value 1.
To complete with a different severity, call tell_done with the severity code like this:
tell_done "WARN";tell_done returns with the severity value from the above table, otherwise it returns 1, unless there's an error in which case it returns false.
As a convienence, it's easier to use these functions which do the same thing, only simpler:
Function Equivalent Usual Meaning
---------- ----------------- -----------------------------------------------------
tell_emerg tell_done "EMERG"; syslog: Off the scale!
tell_alert tell_done "ALERT"; syslog: A major subsystem is unusable.
tell_crit tell_done "CRIT"; syslog: a critical subsystem is not working entirely.
tell_fail tell_done "FAIL"; Failure
tell_fatal tell_done "FATAL"; Fatal error
tell_error tell_done "ERROR"; syslog 'err': Bugs, bad data, files not found, ...
tell_warn tell_done "WARN"; syslog 'warning'
tell_note tell_done "NOTE"; syslog 'notice'
tell_info tell_done "INFO"; syslog 'info'
tell_ok tell_done "OK"; copacetic
tell_debug tell_done "DEBUG"; syslog: Really boring diagnostic output.
tell_notry tell_done "NOTRY"; Untried
tell_unk tell_done "UNK"; UnknownWe'll change our simple example to give a FATAL completion:
use Tell ':all';
tell "Frobnicating the biffolator";
sleep 1; # simulate the frobnication process
tell_fatal;Here's how it looks:
Frobnicating the biffolator....................................... [FATAL]Severity Colors
A spiffy little feature of Tell is that you can enable colorization of the severity codes. That means that the severity code inside the square brackets is printed in color, so it's easy to see. The standard ANSI color escape sequences are used to do the colorization.
Here's the colors:
EMERG bold red on black
ALERT bold magenta
CRIT bold red
FAIL bold red
FATAL bold red
ERROR red
WARN yellow (usually looks orange)
NOTE cyan
INFO green
OK green
DEBUG grey on yellow/orange
NOTRY black on grey
UNK bold white on grey
DONE default font color (unchanged)To use colors, do this when you use Tell:
use Tell ":all", {-colors => 1};
-or-
Tell::set(-colors => 1);Run sample003.pl, included with this module, to see how it looks on your terminal.
Nested Messages
Nested calls to tell will automatically indent with eachother. You do this:
use Tell ":all";
tell "Aaa";
tell "Bbb";
tell "Ccc";and you'll get output like this:
Aaa...
Bbb...
Ccc.......................... [DONE]
Bbb............................ [DONE]
Aaa.............................. [DONE]Notice how "Bbb" is indented within the "Aaa" item, and that "Ccc" is within the "Bbb" item. Note too how the Bbb and Aaa items were repeated because their initial lines were interrupted by more-inner tasks.
You can control the indentation with the -step attribute, and you may turn off or alter the repeated text (Bbb and Aaa) as you wish.
Nesting Across Processes
If you write a Perl script that uses Tell, and this script invokes other scripts that also use Tell, some nice magic happens. The inner scripts become aware of the outer, and they "nest" their indentation levels appropriately. Pretty cool, eh?
Closing with Different Severities, or... Why Autocompletion is Nice
So far our examples have been rather boring. They're not vey real-world. In a real script, you'll be doing various steps, checking status as you go, and bailing out with an error status on each failed check. It's only when you get to the bottom of all the steps that you know it's succeeded. Here's where tell becomes more useful:
use Tell qw/:all/, {-closestat => "ERROR"};
tell "Juxquolating the garfibnotor";
return
if !do_kibvoration();
return
if !do_rumbalation();
$fail_reason = do_major_cleanup();
if ($fail_reason) {
return tell_warn {-reason => $fail_reason};
}
tell_ok;Every use of C<tell> increases the current message levelIn this example, we set -closestat to "ERROR". This means that if we exit scope without doing a tell_done() (or its equivalents), a tell_error() will automatically be called.
Next we do_kibvoration and do_runbalation (whatever these are!). If either fails, we simply return. Automatically then, the tell_error() will be called to close out the context.
In the third step, we do_major_cleanup(). If that fails, we explicitly close out with a warning (the tell_warn), and we can pass some reason text.
If we get thru all three steps, we close out with an OK.
Output to Other File Handles
By default, Tell writes its output to STDOUT (or whatever select() is set to). You can tell Tell to use another file handle like this:
use Tell qw/:all/, {-fh => *LOG};
-or-
Tell::set(-fh => *LOG);Individual "tell" lines may also take a file handle as the first argument, in a manner similar to a print statement:
tell *LOG, "this", " and ", "that";Note the comma after the *LOG -- if it was a print you would omit the comma.
Output to Strings
If you give Tell a scalar (string) reference instead of a file handle, then Tell's output will be appended to this string.
For example:
my $out = "";
use Tell qw/:all/, {-fh => \$out};
-or-
Tell::set(-fh => \$out);Individual "tell" lines may also take a scalar reference as the first argument:
tell \$out, "this ", " and ", "that";Output Independence
Tell separates output contexts by file handle. That means the indentation, autoclosure, bullet style, width, etc. for any output told to STDERR is independent of output told to STDOUT, and independent of output told to a string. All string output is lumped together into one context.
Return Status
Like print, the tell function returns a true value on success and false on failure. Failure can occur, for example, when attempting to tell to a closed filehandle.
Note that to get the return status, you must assign into a scalar context, not a list context:
my $stat;
$stat = tell "Whatever"; # OK. This puts status into $stat
($stat) = tell "Whatever"; # NOT what it looks like!In list context, the closure for tell is bound to the list variable's scope and autoclosure is disabled. Probably not what you wanted.
Message Bullets
You may preceed each message with a bullet. A bullet is usually a single character such as a dash or an asterix, but may be multiple characters. You probably want to include a space after each bullet, too.
You may have a different bullet for each nesting level. Levels deeper than the number of defined bulelts will use the last bullet.
Define bullets by passing an array reference of the bullet strings with -bullet. If you want the bullet to be the same for all levels, just pass the string. Here's some popular bullet definitions:
-bullets => "* "
-bullets => [" * ", " + ", " - ", " "]Here's an example with bullets turned on:
* Loading system information...
+ Defined IP interface information................................ [OK]
+ Running IP interface information................................ [OK]
+ Web proxy definitions........................................... [OK]
+ NTP Servers..................................................... [OK]
+ Timezone settings............................................... [OK]
+ Internal clock UTC setting...................................... [OK]
+ sshd Revocation settings........................................ [OK]
* Loading system information........................................ [OK]
* Loading current CAS parameters.................................... [OK]
* RDA CAS Setup 8.10-2...
+ Updating configuration...
- System parameter updates...................................... [OK]
- Updating CAS parameter values...
Updating default web page index............................. [OK]
- Updating CAS parameter values................................. [OK]
+ Updating configuration.......................................... [OK]
+ Forced stopping web server...................................... [OK]
+ Restarting web server........................................... [OK]
+ Loading crontab jobs...remcon................................... [OK]
* RDA CAS Setup 8.10-2.............................................. [DONE]EXPORTS
Nothing is exported by default. You'll want to do one of these:
use Tell qw/tell tell_done/; # To get just these two functions
use Tell qw/:syslog/; # To get base functions plus syslog severities only
use Tell qw/:all/; # To get all functionsMost of the time, you'll want the :all form.
INTERFACE
Although an object-oriented interface exists for Tell, it is uncommon to use it that way. The recommended interface is to use the class methods in a procedural fashion. Use tell() similar to how you would use print().
Methods
The following subsections list the methods available:
base
Internal base object accessor. Called with no arguments, it returns the Tell object associated with the default output filehandle. When called with a filehandle, it returns the Tell object associated with that filehandle.
clone
Clones the current Tell object and returns a new copy. Any given attributes override the cloned object. In most cases you will NOT need to clone Tell objects yourself.
new
Constructor for a Tell:: object. In most cases you will NOT need to create Tell objects yourself.
set
Sets attributes on a Tell object, for example to enable colored severities, or to set the indentation step size. You will usually call it as a class method, like this:
Tell::set(-fh => *MYLOG,
-step => 3,
-color => 1);tell
Use tell to emit a message similar to how you would use print.
Procedural call syntax:
tell LIST
tell *FH, LIST
tell \$out, LIST
tell {ATTRS}, LISTObject-oriented call syntax:
$tobj->tell (LIST)
$tobj->tell (*FH, LIST)
$tobj->tell (\$out, LIST)
$tobj->tell ({ATTRS}, LIST)tell_done
Closes the current message level, re-printing the message if necessary, printing dot-dot trailers to get proper alignment, and the given completion severity.
tell_alert
tell_crit
tell_debug
tell_emerg
tell_error
tell_fail
tell_fatal
tell_info
tell_note
tell_notry
tell_ok
tell_unk
tell_warn
All these are convienence methods that call tell_done() with the indicated severity. For example, tell_fail() is equivalent to tell_done "FAIL".
tell_none
This is equivalent to tell_done, except that it does NOT print a wrapup line or a completion severity. It simply closes out the current level with no message.
tell_over
tell_prog
Tells a progress indication, such as a percent or M/N or whatever you devise. In fact, this simply puts *any* string on the same line as the original message (for the current level).
Using tell_over will first backspace over a prior progress string (if any) to clear it, then it will write the progress string. The prior progress string could have been emitted by tell_over or tell_prog; it doesn't matter.
tell_prog does not backspace, it simply puts the string out there.
For example,
use Tell qw/:all/;
tell "Varigating the shaft";
tell_prog '10%...';
tell_prog '20%...';gives this output:
Varigating the shaft...10%...20%...Keep your progress string small! The string is treated as an indivisible entity and won't be split. If the progress string is too big to fit on the line, a new line will be started with the appropriate indentation.
With creativity, there's lots of progress indicator styles you could use. Percents, countdowns, spinners, etc. Look at sample005.pl included with this package. Here's some styles to get you thinking:
Style Example output
----- --------------
N 3 (overwrites prior number)
M/N 3/7 (overwrites prior numbers)
percent 20% (overwrites prior percent)
dots .... (these just go on and on, one dot for every step)
tics .........:.........:...
(like dots above but put a colon every tenth)
countdown 9... 8... 7...
(liftoff!)tell_text
This prints the given text without changing the current level. Use it to give additional information, such as a blob of description. A lengthy lines will be wrapped to fit nicely in the given width.
Attributes
The tell* functions, set(), and use Tell take the following optional attributes. Supply options and their values as a hash reference, like this:
use Tell ':all', {-fh => \$out,
-step => 1,
-color => 1};
tell {-fh => *LOG}, "This and that";
tell {-color => 1}, "More of the same";The leading dash on the attribute name is optional, but encouraged; and the attribute may be any letter case, but all lowercase is preferred.
-adjust_level
Only valid for tell and tell_text. Supply an integer value.
This adjusts the indentation level of the message inwards (positive) or outwards (negative) for just this message. It does not affect filtering via the maxdepth attribute. But it does affect the bullet character(s) if bullets are enabled.
-bullets
Enables or disables the use of bullet characters in front of messages. Set to a false value to disable the use of bullets - this is the default. Set to a scalar character string to enable that character(s) as the bullet. Set to an array reference of strings to use different characters for each nesting level. See "Message Bullets".
-closestat
Sets the severity code to use when autocompleting a tell message. This is set to "DONE" by default. See "Closing with Different Severities, or... Why Autocompletion is Nice" above.
-color
Set to a true value to render the completion severities in color. ANSI escape sequences are used for the colors. The default is to not use colors. See "Severity Colors" above.
-ellipsis
Sets the string to use for the ellipsis at the end of a message. The default is "..." (three periods). Set it to a short string. This attribute is often used in combination with -trailer.
Frobnicating the bellfrey...
^^^_____ These dots are the ellipsis-envbase
May only be set before making the first tell() call.
Sets the base part of the environment variable used to maintain level-context across process calls. See "CONFIGURATION AND ENVIRONMENT".
-fh
Designates the filehandle or scalar to receive output. You may alter the default output, or specify it on individual tell* calls.
use Tell ':all', {-fh => *STDERR}; # Default output to STDERR
tell "This goes to STDERR";
tell {-fh => *STDOUT}, "This goes to STDOUT";
tell {-fh => \$outstr}, "This goes to a string";Note, the tell* methods have a shorthand notation for the filehandle. If the first argument is a filehandle or a scalar reference, it is presumed to be the -fh attribute. So the last two lines of the above example could be written like this:
tell *STDOUT, "This goes to STDOUT";
tell \$outstr, "This goes to a string";The default filehandle is whatever was select()'ed, which is typically STDOUT.
-maxdepth
Only valid with set() and use Tell.
Filters messages by setting the maximum depth of messages to emit. Set to undef (the default) to see all messages. Set to 0 to disable all messages from Tell. Set to a positive integer to see only messages at that depth and less.
-reason
Only valid for tell_done (and its equivalents like tell_warn, tell_error, etc.).
Causes tell_done() to emit the given reason string on the following line(s), indented underneath the completed message. This is useful to supply additional failure text to explain to a user why a certain task failed.
This programming metaphor is commonly used:
.
.
.
my $fail_reason = do_something_that_may_fail();
return tell_fail {-reason => $fail_reason)
if $fail_reason;
.
.
.-step
Sets the indentation step size (number of spaces) for nesting messages. The default is 2. Set to 0 to disable indentation - all messages will be left justified. Set to a small positive integer to use that step size.
-trailer
The single character used to trail after a message up to the completion severity. The default is the dot (the period, "."). Here's what messages look like if you change it to an underscore:
The code:
use Tell ':all', {-trailer => '_'};
tell "Xerikineting";
The output: use Tell ':all';
use Term::Size::Any 'chars';
my ($cols, $rows) = chars();
Tell::set(-width => $cols);
Xerikineting...______________________________ [DONE]Note that the elipses after the message are still "..."; use -elipses to change that string as well.
-width
Set to the terminal width of your output device. Tell has no idea how wide your terminal screen is, so use this attribute to indicate the width. The default is 80.
You may want to use Term::Size::Any to determine your device's width:
use Tell ':all';
use Term::Size::Any 'chars';
my ($cols, $rows) = chars();
Tell::set(-width => $cols);
.
.
.CONFIGURATION AND ENVIRONMENT
Tell requires no configuration files or environment variables. However, it does set environment variables with this form of name:
tell_fd#_th#This envvar holds the current level of messages (represented visually by indentation), so that indentation can be smoothly maintained across process contexts.
In this envvar's name, fd# is the fileno() of the output file handle to which the messages are written. By default output is to STDERR, which has a fileno of 2, so the envvar would be tell_fd2. If output is being written to a string (-fh = \$some_string>), then fd# is the string "str", for example tell_fdstr
When Tell is used with threads, the thread ID is placed in th# in the envvar. Thus for thread #7, writing Tell messages to STDERR, the envvar would be tell_fd2_th7. For the main thread, th# and the leading underscore are omitted.
Under normal operation, this environment variable is deleted before the program exits, so generally you won't see it.
Note: If your program's output seems excessively indented, it may be that this envvar has been left over from some other aborted run. Check for it and delete it if found.
DEPENDENCIES
This pure-Perl module depends upon Scope::Upper.
INCOMPATIBILITIES
None reported.
BUGS AND LIMITATIONS
Limitation: Output in a threaded environment isn't always pretty. It works OK and won't blow up, but indentation may get a bit screwy.
Bugs: No bugs have been reported.
Please report any bugs or feature requests to bug-Tell@rt.cpan.org, or through the web interface at http://rt.cpan.org.
SEE ALSO
To format Tell output to HTML, use Tell::Format::HTML .
Other modules like Tell but not quite the same:
Debug::Message
Log::Dispatch
PTools::DebugAUTHOR
Steve Roscio <roscio@cpan.org>
ACKNOWLEDGEMENTS
Thanx to Paul Vencel for his review of this package.
LICENCE AND COPYRIGHT
Copyright (c) 2009, Steve Roscio <roscio@cpan.org>. All rights reserved.
This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See perlartistic.
DISCLAIMER OF WARRANTY
Because this software is licensed free of charge, there is no warranty for the software, to the extent permitted by applicable law. Except when otherwise stated in writing the copyright holders and/or other parties provide the software "as is" without warranty of any kind, either expressed or implied, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. The entire risk as to the quality and performance of the software is with you. Should the software prove defective, you assume the cost of all necessary servicing, repair, or correction.
In no event unless required by applicable law or agreed to in writing will any copyright holder, or any other party who may modify and/or redistribute the software as permitted by the above licence, be liable to you for damages, including any general, special, incidental, or consequential damages arising out of the use or inability to use the software (including but not limited to loss of data or data being rendered inaccurate or losses sustained by you or third parties or a failure of the software to operate with any other software), even if such holder or other party has been advised of the possibility of such damages.