Recommended command line options for new rubyists

Ruby
1

Hi guys,

There are loooads of ruby docs out there. There are also some good
reference guides under /usr/share/doc/ruby-1.8.3,
/usr/share/doc/ruby-docs-1.8.3 and /usr/share/doc/ruby-libs-1.8.3. What
would the more experienced of you recommend for command line options? So
far I’ve been using
ruby -c foo.rb
ruby -W foo.rb
as they are the simplest :slight_smile: I’ve not really used irb that much as I
haven’t seen any advantage in using it.

2

Hi –

On Thu, 5 Jan 2006, John M. wrote:

haven’t seen any advantage in using it.
The ones I use the most are:

ruby -cw
ruby -v[e]
ruby -e
ruby -p[i.bak][ -e]
ruby -n[i.bak][ -e]

David

–
David A. Black
[email protected]

“Ruby for Rails”, from Manning Publications, coming April 2006!

3

Hi –

On Thu, 5 Jan 2006, John M. wrote:

I find it strange that ruby -c foo.rb gives “syntax OK” but ruby -w
foo.rb shows me all of the syntax errors. In the example below i
make a deliberate mistake…

You do, but it’s not a syntax error; it’s a runtime error. -c doesn’t
run the code, but only checks it for syntax. -w runs the code.

David

David A. Black
[email protected]

“Ruby for Rails”, from Manning Publications, coming April 2006!

4

I find it strange that ruby -c foo.rb gives “syntax OK” but ruby -w
foo.rb shows me all of the syntax errors. In the example below i make a
deliberate mistake…

#script

#!/usr/bin/ruby
#Wed Jan 4 06:17:22 GMT 2006
class Menu
def initialize(welcome, stage, usage)
@welcome = print “Welcome to
de-blah-de-blah-de-blah\n\n\n”
@usage = usage # we will use this as a user
guide
@stage = stage
#date
#print “which stage are you at?
#b:- before site work
#d:- during site work
#a:- atfer site work
#q:- quit!\n”
end
def to_s
“Deskstudy: #@welcome #@usage #@stage”
end
end

#menu = Menu.new(“welcome”, “usage”, “stage”)
menu = Menu.new(“welcome”, “stage”)
menu.inspect
puts menu

#errors

menu.rb:21:in `initialize’: wrong number of arguments (2 for 3)
(ArgumentError)
from menu.rb:21

On Thu, 5 Jan 2006 04:25:54 +0900

5

unknown wrote:

Hi –

On Thu, 5 Jan 2006, John M. wrote:

I find it strange that ruby -c foo.rb gives “syntax OK” but ruby -w
foo.rb shows me all of the syntax errors. In the example below i
make a deliberate mistake…

You do, but it’s not a syntax error; it’s a runtime error. -c doesn’t
run the code, but only checks it for syntax. -w runs the code.

Or to give a simpler testcase:

$ cat div0
#!/usr/bin/env ruby
puts 5/0

$ ruby -c div0
Syntax OK

$ ruby -w div0
div0:2:in `/’: divided by 0 (ZeroDivisionError)
from div0:2