I'm running the Ruby irb on a DOS environment.
I've defined a dictionary.
irb(main):001:0> stuff = {'name'=> 'Zed', 'age'=>36, 'height'=>6*12+2}
I've made a mistake in calling it
irb(main):004:0> puts stuff['age]
the ruby prompt changes to an apostrophe ' instead of the usual >
irb(main):006:1'
irb(main):007:1'
IRB doesn't work anymore.
What has happened here and how do I get the shell to function again without quitting the program?
It is waiting for the closing ',that you missed here puts stuff['age]. Use Ctrl+c to get the prompt back,that you are expecting.
See below:
2.0.0p0 :001 > stuff = {'name'=> 'Zed', 'age'=>36, 'height'=>6*12+2}
=> {"name"=>"Zed", "age"=>36, "height"=>74}
2.0.0p0 :002 > puts stuff['age]
2.0.0p0 :003'> ^C
2.0.0p0 :003 >
Related
If i put the following code:
a = 42
p TOPLEVEL_BINDING.local_variable_defined?(:a)
in a file "rubyScratch.rb" and ruby it using
ruby rubyScratch.rb
I get
true
However in irb I get
2.3.1 :001 > a = 42
=> 42
2.3.1 :002 > TOPLEVEL_BINDING.local_variable_defined?(:a)
=> false
Why is there this difference?
This is because the irb command (on my system, anyways) runs a small ruby script that looks like this:
#!/usr/bin/env ruby
#
# irb.rb - interactive ruby
# $Release Version: 0.9.6 $
# $Revision: 40560 $
# by Keiju ISHITSUKA(keiju#ruby-lang.org)
#
require "irb"
IRB.start(__FILE__)
So, the TOPLEVEL_BINDING is this script and not your IRB context.
While looking for some more information, I ran across this short article which states:
It is, as its name suggest, the Binding of your script's main scope:
a = 42
p binding.local_variable_defined?(:a) # => true
p TOPLEVEL_BINDING.local_variable_defined?(:a) # => true
def example_method
p binding.local_variable_defined?(:a) # => false
p TOPLEVEL_BINDING.local_variable_defined?(:a) # => true
end
example_method
To summarize, the TOPLEVEL_BINDING is the binding for the first script in the current context that was run by the Ruby VM. When running IRB, that script is the one that starts the IRB session.
I'm learning Ruby, and went into irb to test something out with the Date class. In short, I did the following:
$ irb
irb(main):001:0> Date.new
=> #<Date:0x007f983103ee60>
irb(main):002:0> Date.constants
=> []
irb(main):003:0> help Date
=> nil
irb(main):004:0> Date.constants
=> [:MONTHNAMES, :ABBR_MONTHNAMES, :DAYNAMES, :ABBR_DAYNAMES, :ITALY, :ENGLAND, :JULIAN, :GREGORIAN, :Infinity]
irb(main):005:0>
I'm so confused by this. Questions:
Why would reading help documentation cause the output of Date.constants to change?
Presumably help is loading/initializing something. What is it? And why did Date.new work?
Is whatever this is something I need to worry about when writing .rb files?
This is tough to Google for. I'm on ruby 2.1.2 and irb 0.9.6.
The most likely cause of the addition of the Date constants after running help Date is that somewhere in the execution of the command, require 'date' (or require 'time') is called:
2.1.0 :001 > Date.constants
=> []
2.1.0 :002 > require 'date'
=> true
2.1.0 :003 > Date.constants
=> [:MONTHNAMES, :ABBR_MONTHNAMES, :DAYNAMES, :ABBR_DAYNAMES, :ITALY, :ENGLAND, :JULIAN, :GREGORIAN, :Infinity]
As for Date.new, it works because Date comes with a default constructor.
I doubt this will ever be problematic for you.
Suppose I have a string "this\n\tis \"helpful\"" and I'd like it to be displayed in the terminal, unescaped, for copy/paste reasons, i.e.
this
is "helpful"
Is this possible in terminal, either in IRB or otherwise?
11:15:14lasto1.9.3 ~/clients 🐤 irb
1.9.3-p448 :001 > s = "this\n\tis \"helpful\""
=> "this\n\tis \"helpful\""
1.9.3-p448 :002 > puts s
this
is "helpful"
=> nil
1.9.3-p448 :003 >
I'm trying to prettify an Ruby object using awesome_print so I can place this string inside an email and send it off. So in terms of code, (I know this is wrong), but here's what I'm trying to achieve:
my_str = (ap error.object).to_str
# Do something with my_str, like stick it in a <pre> tag inside an html email.
How do I convert the output from ap to string? Reason I'm asking is as I noticed, ap seems to only return the object.
It doesn't seem to be documented in the README.md, but if you look at the Kernel modifications the library makes here: https://github.com/michaeldv/awesome_print/blob/master/lib/awesome_print/core_ext/kernel.rb
You can see that in addition to the ap method, the awesome_print gem also adds an ai method to all objects.
1.9.3p392 :001 > require 'awesome_print'
=> true
1.9.3p392 :002 > test = {a: "b"}
=> {:a=>"b"}
1.9.3p392 :003 > ap test
{
:a => "b"
}
1.9.3p392 :006 > test.ai
=> "{\n :a\e[0;37m => \e[0m\e[0;33m\"b\"\e[0m\n}"
1.9.3p392 :007 > test.ai(html:true)
=> "<pre>{\n <pre>:a</pre><kbd style=\"color:slategray\"> => </kbd><pre><kbd style=\"color:brown\">"b"</kbd></pre>\n}</pre>"
That said, the output formatting might not be that useful (the html version adds a ton of whitespace, and the non-html version has the weird terminal coloring characters), and being an undocumented feature, it's liable to break without warning in a minor version update.
The other thing worth noting in the kernel.rb above is that ap and ai have aliases: awesome_print and awesome_inspect.
awesomeprint is meant for printing ASCII colors and stuff, not HTML. What I'd use is pygments gem:
# gem install pygments.rb
require 'pygments'
str = <<EOT
# This is an awesome comment on my rb script
a = 2
puts a
hsh = {asdf: 1, qwer: 2, uiop: 3}
EOT
Pygments.highlight str
https://github.com/tmm1/pygments.rb
I'm using a Ruby 1.8 lib kakasi-ruby, but it seems that it can only be compiled against Ruby 1.8 (https://github.com/hogelog/kakasi-ruby/issues/2)
My application is Ruby 1.9.3, so I need to call kakasi-ruby from Ruby 1.9.3.
How should I do?
Do I have to open a subprocess with Ruby 1.8, and wait for it finish to get the process return value?
Edit:
https://github.com/hogelog/kakasi-ruby
Found 3 possible paths:
There seems to be a branch for 1.9 in the repo. Maybe try to compile that instead?
Otherwise your fastest option is probably to go back to 1.8 depending on what kind of app it is.
Calling with 1.8 may work BUT since the library seems to be a binding to some C code you could probably call that code directly just as well.
BTW, here is the usage in Ruby 1.9
plee#sos:~/Japanese$ irb
1.9.3p194 :001 > require 'kakasi'
=> true
1.9.3p194 :002 > src="前原誠司経済財政相は４日、朝日新聞などのインタビューに対し"
=> "前原誠司経済財政相は４日、朝日新聞などのインタビューに対し"
1.9.3p194 :003 > src=src.encode("EUC-JP", "UTF-8")
=> "\x{C1B0}\x{B8B6}\x{C0BF}\x{BBCA}\x{B7D0}\x{BAD1}\x{BAE2}\x{C0AF}\x{C1EA}\x{A4CF}\x{A3B4}\x{C6FC}\x{A1A2}\x{C4AB}\x{C6FC}\x{BFB7}\x{CAB9}\x{A4CA}\x{A4C9}\x{A4CE}\x{A5A4}\x{A5F3}\x{A5BF}\x{A5D3}\x{A5E5}\x{A1BC}\x{A4CB}\x{C2D0}\x{A4B7}"
1.9.3p194 :004 > dst=Kakasi.kakasi("-w", src)
=> "\xC1\xB0\xB8\xB6 \xC0\xBF\xBB\xCA \xB7\xD0\xBA\xD1 \xBA\xE2\xC0\xAF \xC1\xEA \xA4\xCF \xA3\xB4 \xC6\xFC \xA1\xA2 \xC4\xAB\xC6\xFC\xBF\xB7\xCA\xB9 \xA4\xCA\xA4\xC9\xA4\xCE \xA5\xA4\xA5\xF3\xA5\xBF\xA5\xD3\xA5\xE5\xA1\xBC \xA4\xCB \xC2\xD0\xA4\xB7"
1.9.3p194 :005 > dst.force_encoding("EUC-JP")
=> "\x{C1B0}\x{B8B6} \x{C0BF}\x{BBCA} \x{B7D0}\x{BAD1} \x{BAE2}\x{C0AF} \x{C1EA} \x{A4CF} \x{A3B4} \x{C6FC} \x{A1A2} \x{C4AB}\x{C6FC}\x{BFB7}\x{CAB9} \x{A4CA}\x{A4C9}\x{A4CE} \x{A5A4}\x{A5F3}\x{A5BF}\x{A5D3}\x{A5E5}\x{A1BC} \x{A4CB} \x{C2D0}\x{A4B7}"
1.9.3p194 :006 > dst=dst.encode("UTF-8", "EUC-JP")
=> "前原 誠司 経済 財政 相 は ４ 日 、 朝日新聞 などの インタビュー に 対し"
1.9.3p194 :007 >