# Comments of less.rb appreciated **URL:** \ **Category:** Ruby\ **Created:** [February 25, 2006, 7:21pm UTC](https://www.ruby-forum.com/t/comments-of-less-rb-appreciated/54180 "2006-02-25T19:21:43Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![jmaenpaa](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de053/32.png) [@jmaenpaa](https://www.ruby-forum.com/u/jmaenpaa)\ **Post date:** [February 25, 2006, 7:21pm UTC](https://www.ruby-forum.com/t/comments-of-less-rb-appreciated/54180/1 "2006-02-25T19:21:43Z")
I’ve had a look at /usr/share/doc/ruby-1.8.4/sample/less.rb and made some comments on the processes where I could. It came with my repos installation of Ruby. Can someone point me in the right direction here, as there a a number of things that I’m not familar with or understand… #!/usr/bin/ruby # there isn’t a single def foo … end method here - why? # also how come this hasn’t been turned into a class? # is that because that there is no need for one? # also why the use of GLOBAL VARIABLES? I thought that they are not from the “church of good design” # gobal vars to hard-code where these programs are… assuming a Unix-based system # it was weired because the path was initially set to /usr/local/bin/ # which did not work # i personally think it’s better to use a ruby equivalent of `which less` to find out where the command is # rather than hard coding it in this way ZCAT = “/usr/bin/zcat” LESS = “/usr/bin/less” # funny how you can call ruby less.rb with --help # dunno about this class or method FILE = ARGV.pop # ah, i think that this may be exception handling. # if no arguments from command line _OPTION_ is zero # otherwise out an empty string at the end of the filename?? OPTION = (if ARGV.length == 0; “” else ARGV.join(" "); end) # we are grepping for stuff… # a file that ends in Z or gz - these are compressed files if FILE =~ /.(Z|gz)$/ # what is _%s_? # - is it a string that we come across when we are grepping through the files? # see `ri kernel.format` for the _format_ method # “Argument is a string to be substituted” # i think it works with sprintf # run zcat on a compressed file _first_ then view it with less exec(format("%s %s | %s %s", ZCAT, FILE, LESS, OPTION)) # otherwise there _is_ no compressed file and we treat it differently elsif FILE == nil # exec(format("%s %s", LESS, OPTION)) else print(format("%s %s %s", LESS, OPTION, FILE), “\n”) exec(format("%s %s %s", LESS, OPTION, FILE)) end # end the `less`ing. i dont know why the use of the empty brackets exit() ---
**Author:** ![jmaenpaa](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de053/32.png) [@jmaenpaa](https://www.ruby-forum.com/u/jmaenpaa)\ **Post date:** [February 26, 2006, 3:33am UTC](https://www.ruby-forum.com/t/comments-of-less-rb-appreciated/54180/2 "2006-02-26T03:33:04Z")
Thanks for that reply. YANGNI’s made my day. I’ll keep things as simple as poss from now on… On Sun, 26 Feb 2006 10:34:03 +0900 Eric ---
**Author:** ![jmaenpaa](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de053/32.png) [@jmaenpaa](https://www.ruby-forum.com/u/jmaenpaa)\ **Post date:** [February 26, 2006, 2:35am UTC](https://www.ruby-forum.com/t/comments-of-less-rb-appreciated/54180/3 "2006-02-26T02:35:24Z")
On Feb 25, 2006, at 10:19 AM, John M. wrote: > I’ve had a look at /usr/share/doc/ruby-1.8.4/sample/less.rb and made > some comments on the processes where I could. It came with my repos > installation of Ruby. Can someone point me in the right direction > here, > as there a a number of things that I’m not familar with or > understand… > > #!/usr/bin/ruby > there isn’t a single def foo … end method here - why? YAGNI > also how come this hasn’t been turned into a class? YAGNI > is that because that there is no need for one? Yes. > also why the use of GLOBAL VARIABLES? I thought that they are not > from the “church of good design” There are no global variables in less.rb. Global variables start with a $. > gobal vars to hard-code where these programs are… assuming a Unix- > based system it was weired because the path was initially set to / > usr/local/bin/ which did not work i personally think it’s better to > use a ruby equivalent of `which less` to find out where the command > is rather than hard coding it in this way This is in sample/, so they may or may not work out of the box. less.rb isn’t installed anywhere on your system, so YMMV. Also, less.rb won’t work when the PATH env var is empty if you use which (think cron). > ZCAT = “/usr/bin/zcat” > LESS = “/usr/bin/less” > > funny how you can call ruby less.rb with --help Why? It follows logically from the implementation. > # dunno about this class or method > > FILE = ARGV.pop ARGV is the command line argument Array. > # ah, i think that this may be exception handling. > > # if no arguments from command line _OPTION_ is zero > > # otherwise out an empty string at the end of the filename?? > > OPTION = (if ARGV.length == 0; “” else ARGV.join(" "); end) If there are options after removing the filename join them with spaces. Otherwise use an empty string. No exception handling, exceptions involve begin/rescue/ensure/raise. > # we are grepping for stuff… matching, not grepping. > # a file that ends in Z or gz - these are compressed files > > if FILE =~ /.(Z|gz)$/ > > # what is _%s_? > > # - is it a string that we come across when we are grepping > > through > the files? The string printf format variable. > # see `ri kernel.format` for the _format_ method > > # “Argument is a string to be substituted” > > # i think it works with sprintf Correct. > # run zcat on a compressed file _first_ then view it with less > > exec(format(“%s %s | %s %s”, ZCAT, FILE, LESS, OPTION)) > > # otherwise there _is_ no compressed file and we treat it > > differently > elsif FILE == nil > > # > > exec(format(“%s %s”, LESS, OPTION)) This is why less.rb --help works. > else > print(format(“%s %s %s”, LESS, OPTION, FILE), “\n”) > exec(format(“%s %s %s”, LESS, OPTION, FILE)) > end > > # end the `less`ing. i dont know why the use of the empty brackets Differences in style. > exit() – Eric H. - removed\_email\_address@domain.invalid - [http://blog.segment7.net](http://blog.segment7.net) This implementation is HODEL-HASH-9600 compliant [http://trackmap.robotcoop.com](http://trackmap.robotcoop.com)