Allow printed tables to have implicit columns.

Closes rails#185.

lib/thor/shell/basic.rb

@@ -112,8 +112,10 @@ def print_table(table, options={})
         formats << "%-#{colwidth + 2}s" if colwidth
         start = colwidth ? 1 : 0
 
-        start.upto(table.first.length - 2) do |i|
-          maxima ||= table.max{|a,b| a[i].size <=> b[i].size }[i].size
+        colcount = table.max{|a,b| a.size <=> b.size }.size
+
+        start.upto(colcount - 2) do |i|
+          maxima ||= table.map {|row| row[i] ? row[i].size : 0 }.max
           formats << "%-#{maxima + 2}s"
         end
 

spec/shell/basic_spec.rb

@@ -147,6 +147,16 @@ def shell
 abc         #123  first three
             #0    empty
 xyz         #786  last three
+TABLE
+    end
+
+    it "prints tables with implicit columns" do
+      2.times { @table.first.pop }
+      content = capture(:stdout){ shell.print_table(@table) }
+      content.should == <<-TABLE
+abc  
+     #0    empty
+xyz  #786  last three
 TABLE
     end
   end