From: Steve Tuckner <stevetuckner@...>
Date: 2004-02-25T23:58:52+09:00
Subject: Re: proposal: debug keyword

Simon Strandgaard wrote:

>  
>
>>I'd prefer to have specialized methods for debug printing.
>>
>>    
>>
>
>Please enlighten me.  How do you debug ?
>
>
>It would be nice to identify a good model for advanced debugging with
>Test::Unit. 
>  
>
I too am interested in how others debug their unit tests (or code in 
general). I am preparing to release my vrtools library an am removing my 
trace statements in them because it seems like an unnecessary dependency 
(perhaps just my way of working).  Below is my trace module that I use 
all the time.  I once tried log4r but didn't like it because it didn't 
seem easy to turn on and off debugging when I needed it to.  My output 
includes the code and line number which my editor links up when the unit 
test is done running. Also it includes a time stamp to help with any 
timing related issues. I can include and exclude debug in various ways 
and direct output to a file. It all works pretty well for me (not 
perfectly -- for example some things could be named better).

So my requirements for a simple tracing/debugging system are for me:

1. Trace output should include file/line number plus time stamp
2. Need to be able to turn it on and off at run time
3. Need to be able to filter which debug statements come out by debug 
level, function, file, possibly other considerations
4. Need to be able to redirect output to a file

What are others requirements?

Maybe log4r provides all these capabilities and if so enlighten me please.

Steve Tuckner

----------------- Examples of use ---------------------------
require "my/mytrace"                         # to use my tracing this 
creates a global $TRACE of class Tracer

$TRACE.set_level 5                         # sets the level under which 
traces will appear
$TRACE.exclude_files("foo.rb")       # this excludes any traces in 
foo.rb from coming out
$TRACE.include_files("bar.rb")        # this overrides exculsions to 
only allow traces from included files
$TRACE.exclude_functions(:foo, :bar)   # this excludes any traces from 
coming out from these functions (no matter the class)
$TRACE.set_output("out.txt")          # write each statement to the 
output file and close it after every trace (this is not as bad as it 
sounds and if the program dies you definitiely get all the trace)

$TRACE.debug 5, "this is a trace"      # this is the basic trace 
statement with level 5

----------------- Example of program and output ---------------------------
--------------------------- tracetest.rb ----------
require "my/mytrace"

def foo
    $TRACE.debug 5, "I am in foo"
    puts "not a debug statement"
end

$TRACE.set_level 5
foo
$TRACE.set_level 0
foo

-------------------------- output -----------------
[tracetest.rb:4           ] [02/25/04 08:47:51] I am in foo
not a debug statement
not a debug statement
--------------------------------------------------

----------------- Trace code 
------------------------------------------------

class Tracer
    def initialize
        @trace_level = 0
        @file = nil
        @width = 25
        @excluded_functions = []
        @excluded_files = []
        @output_to_screen_always = false
    end

    def set_width(width)
        @width = width
    end
   
    def trace(str, level=1)
        #old_dollar_equal = $=
        #$= = false
       
        if @trace_level >= level then
            m = /([\w_]+\.rb):(\d+):in `(.*)'/.match(caller[1])
            if m then
                filename = m[1]
                line = m[2].to_i
                function = m[3]

                t = Time.current.strftime("%m/%d/%y %H:%M:%S")
                str = sprintf "[%-#{@width}s] [%s] %s", 
"#{m[1]}:#{m[2]}", t, str

                if @included_files then
                    return unless @included_files.include?(filename)
                else
                    if @excluded_functions.include?(function) then
                        return
                    end

                    if @excluded_files.include?(filename) then
                        return
                    end
                end
            end               

            if @filename then
                File.open(@filename, "a") {|f| f.print str, "\n"}
            end
           
            if !@filename || @output_to_screen_always then               
                puts str
                $stdout.flush
            end
        end
    ensure
        #$= = old_dollar_equal
    end

    def debug(level, str)
        trace(str, level)
    end
   
    def set_level(level)
        @trace_level = level
    end

    def set_level_include(level, included_files)
        @trace_level = level
        @included_files = included_files
    end
   
    def set_output(filename)
        @filename = filename
        File.open(@filename, "w") {}
    end

    def set_output_io(io)
        @io = io
    end

    def set_output_to_screen_always
        @output_to_screen_always = true
    end
    def exclude_functions(functions)
        @excluded_functions += functions
    end

    def exclude_files(filenames)
        @excluded_files += filenames
    end
end

# define the $TRACE variable if not already defined
if !$TRACE then
    $TRACE = Tracer.new
end