Is there a way to check without raising (and rescuing) an error if a library/gem "foo" is installed on the computer and is available?
Probably, ruby-gems or bundler should have some relevant code in the source, but I cannot spot it.
I spotted the relevant source. I can do:
Checking the entire load path:
Gem.find_files("foo").any?
Checking for only gems:
Gem.find_files("foo", false).any?
If you have installed the pry,then you can do as below using the method Pry::Rubygem.installed?:
kirti#kirti-Aspire-5733Z:~$ irb
2.0.0p0 :001 > require 'pry'
=> true
2.0.0p0 :002 > pry
[1] pry(main)> Pry::Rubygem.installed?('nokogiri')
=> true
[2] pry(main)> Pry::Rubygem.installed?('foo')
=> false
[3] pry(main)>
Or you can do as below:
require 'rubygems'
def installed?(name)
if Gem::Specification.respond_to?(:find_all_by_name)
Gem::Specification.find_all_by_name(name).any?
else
Gem.source_index.find_name(name).first
end
end
installed?('nokogiri') # => true
installed?('foo') # => false
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.
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 >
I'm trying to parse some JSON containing escaped unicode characters using JSON.parse. But on one machine, using json/ext, it gives back incorrect values. For example, \u2030 should return E2 80 B0 in UTF-8, but instead I'm getting 01 00 00. It fails with either the escaped "\\u2030" or the unescaped "\u2030".
1.9.2p180 :001 > require 'json/ext'
=> true
1.9.2p180 :002 > s = JSON.parse '{"f":"\\u2030"}'
=> {"f"=>"\u0001\u0000\u0000"}
1.9.2p180 :003 > s["f"].encoding
=> #<Encoding:UTF-8>
1.9.2p180 :004 > s["f"].valid_encoding?
=> true
1.9.2p180 :005 > s["f"].bytes.map do |x| x; end
=> [1, 0, 0]
It works on my other machine with the same version of ruby and similar environment variables. The Gemfile.lock on both machines is identical, including json (= 1.6.3). It does work with json/pure on both machines.
1.9.2p180 :001 > require 'json/pure'
=> true
1.9.2p180 :002 > s = JSON.parse '{"f":"\\u2030"}'
=> {"f"=>"‰"}
1.9.2p180 :003 > s["f"].encoding
=> #<Encoding:UTF-8>
1.9.2p180 :004 > s["f"].valid_encoding?
=> true
1.9.2p180 :005 > s["f"].bytes.map do |x| x; end
=> [226, 128, 176]
So is there something else in my environment or setup that could be causing it to parse incorrectly?
Recently ran into this same problem, and I tracked it down to this Ruby bug caused by the declaration of this buffer in Ruby 1.9.2 and how it gets optimized by GCC. It's fixed in this commit.
You can recompile Ruby with -O0 or use a newer version of Ruby (1.9.3 or better) to fix it.
Try upgrade your JSON Gem (at least to 1.6.6) or newest 1.7.1.
I am using JSON implementation for Ruby in my rails project to parse the JSON string sent by ajax, but I found that although the json string is in UTF-8, the result coming out is in ASCII-8BIT by default, see below
jruby-1.6.7 :068 > json_text = '["に到着を待っている"]'
=> "[\"に到着を待っている\"]"
jruby-1.6.7 :069 > json_text.encoding
=> #<Encoding:UTF-8>
jruby-1.6.7 :070 > json_parsed = JSON.parse(json_text)
=> ["\u00E3\u0081\u00AB\u00E5\u0088\u00B0\u00E7\u009D\u0080\u00E3\u0082\u0092\u00E5\u00BE\u0085\u00E3\u0081\u00A3\u00E3\u0081\u00A6\u00E3\u0081\u0084\u00E3\u0082\u008B"]
jruby-1.6.7 :071 > json_parsed.first.encoding
=> #<Encoding:ASCII-8BIT>
I don't want it being escaped, I would like to have a UTF-8 result. Is there a way to set that? I check the documentation of the JSON project, finding not encoding options for the method JSON.parse. Maybe I missed something, how could I do that?
UPDATE:
as notified by #fl00r, this example is working fine in MRI, but not in JRUBY
This looks like a bug, as this actually works when using the pure version:
jruby-1.6-head :001 > require 'json/pure'
=> true
jruby-1.6-head :002 > json_text = '["に到着を待っている"]'
=> "[\"に到着を待っている\"]"
jruby-1.6-head :003 > json_parsed = JSON.parse(json_text)
=> ["に到着を待っている"]
jruby-1.6-head :004 > json_parsed.first.encoding
=> #<Encoding:UTF-8>
jruby-1.6-head :005 >
Edit: Just saw you opened a ticket for this...
Edit 2: This actually seems to have already been fixed by this commit. To install latest code from json:
$ git clone https://github.com/flori/json.git
$ cd json
$ rake jruby_gem
$ jruby -S gem install pkg/json-1.6.6-java.gem