From my bag of tricks…
On occasion, I run into the need to present some kind of table information on to a console/terminal session so that the information is readable. After doing this several times, I decided to write a text table class so that i didn’t have to worry about formatting the table within my code. I just set the table up with column titles and column widths and just focus on the data.
Here’s the code:
#
# texttable.rb -- testing tool to output a nicely formatted table.
#
# John Allen, June 2005
# June 2010 -- Added support for word wrap fields
#
class TextTable
#
# tableinfo = Hash.new {
# "name" => Array(:string),
# "width" => Array(:fixnum),
# ["linebetweenrows" => Boolean,]
# ["hdrlinechar" => "=",]
# ["rowlinechar" => "-",]
# ["wordwrap" => Boolean]
# }
attr_accessor :names, :widths, :hdr_print_flg, :lbr_flg, :hdrchar, :linechar, :wordwrap
@hdr_print_flg = false
@ldr_flg = false
@wordwrap = false
def initialize(tableinfo)
@names = tableinfo["name"]
@widths = tableinfo["width"]
if tableinfo["linebetweenrows"]
@lbr_flg = true
end
if tableinfo["wordwrap"]
@wordwrap = true
end
@hdrchar = tableinfo["hdrlinechar"] || "="
@linechar = tableinfo["rowlinechar"] || "-"
end
def printrow(a)
# a = Array
buf = ""
if not @hdr_print_flg
buf << printHdr()
end
buf << "|"
extra = []
a.each_with_index do |n,i|
if n.length > @widths[i] ## check to see if value is bigger than field; chop if so
b = n.slice(0..(@widths[i] -1))
extra[i] = n.slice(@widths[i]..-1)
else
b = n
end
buf << " #{b}#{" "*(@widths[i] - b.length)}|"
end
buf << "\n"
if @wordwrap and not extra.empty? ## Word Wrap
eflg = true
while eflg ## While stuff to word wrap
eflg = false
buf << "|"
extra.each_with_index do |n,i|
if not n.nil?
if n.length > @widths[i] ## check to see if value is bigger than field; chop if so
b = n.slice(0..(@widths[i] -1))
extra[i] = n.slice(@widths[i]..-1)
eflg = true ## still more to word wrap!!
else
b = n
extra[i] = nil
end
buf << " #{b}#{" "*(@widths[i] - b.length)}|"
else
buf << " #{" "*@widths[i]}|" ## add blank space for non-wordwrap field
end
end
buf << "\n"
end
end
buf << _line(@linechar) if @lbr_flg
return buf
end
def printHdr
buf = _line(@hdrchar)
buf << "|"
@names.each_with_index do |n,i|
buf << " #{n}#{" "*(@widths[i] - n.length)}|"
end
buf << "\n"
buf << _line(@hdrchar)
@hdr_print_flg = true
return buf
end
def printLine
buf = _line(@linechar)
return buf
end
#-------------------------------------------------------------------------------------------------------#
private
#-------------------------------------------------------------------------------------------------------#
def _line(char)
b = "+"
@names.each_with_index do |n,i|
b << char*@widths[i]
b << "#{char}+"
end
b << "\n"
return b
end
end
if __FILE__ == $0
tt = {
"name" => ["First","Last","City","State"],
"width" => [15,15,15,6],
"linebetweenrows" => false
}
names = [
["John","Allen","Redmond","WA"],
["Herman","Gonzales","Mill Creek","WA"],
["Jimmy","Doogle","Bothell","WA"],
["Jane","Goodman","Seattle","WA"]
]
table = TextTable.new(tt)
buf = ""
names.each do |name|
buf << table.printrow(name)
end
buf << table.printLine
puts buf
end
Running the example code at the bottom prints out the following result:
C:\Server4\Dev\Ruby\exo>ruby texttable.rb
+================+================+================+=======+
| First | Last | City | State |
+================+================+================+=======+
| John | Allen | Redmond | WA |
| Herman | Gonzales | Mill Creek | WA |
| Jimmy | Doogle | Bothell | WA |
| Jane | Goodman | Seattle | WA |
+----------------+----------------+----------------+-------+
the printrow() method takes an array of String values to print out. You can have a line printed out between each row if you set the linebetweenrows hash value to ‘true’ (it defaults to ‘false’). There is not a lot of error checking (as in, you can crash the program if you feed the printrow() method an array that is shorter than the number of columns), but since I mainly use it for testing or utilities, I didn’t put a lot in. Its a very handy tool to have around.
Update: I added support for word wrap in all fields recently, so I have updated the code above with that version.
), but I didn’t have time to dig into it, so I pulled out my old trusty Lockfile class. 
If the file already exists, then you don’t get the lock. If you can’t open the file, then someone else must have just opened it, and again no lock.
