I'm trying to use the google_search ruby library (code follows) but it complains that 'cattr_accessor is an undefined method' - any ideas why this might be or how I could fix it?
require 'rubygems'
require 'google_search'
GoogleSearch.web :q => "pink floyd"
cattr_accessor seems to be a Rails extension that acts like attr_accessor, but is accessible on both the class and its instances.
If you want to copy the source of the cattr_accessor method, check out this documentation:
# File vendor/rails/activesupport/lib/active_support/core_ext/class/attribute_accessors.rb, line 46
def cattr_accessor(*syms)
cattr_reader(*syms)
cattr_writer(*syms)
end
# File vendor/rails/activesupport/lib/active_support/core_ext/class/attribute_accessors.rb, line 4
def cattr_reader(*syms)
syms.flatten.each do |sym|
next if sym.is_a?(Hash)
class_eval("unless defined? ##\#{sym}\n##\#{sym} = nil\nend\n\ndef self.\#{sym}\n##\#{sym}\nend\n\ndef \#{sym}\n##\#{sym}\nend\n", __FILE__, __LINE__)
end
end
# File vendor/rails/activesupport/lib/active_support/core_ext/class/attribute_accessors.rb, line 24
def cattr_writer(*syms)
options = syms.extract_options!
syms.flatten.each do |sym|
class_eval("unless defined? ##\#{sym}\n##\#{sym} = nil\nend\n\ndef self.\#{sym}=(obj)\n##\#{sym} = obj\nend\n\n\#{\"\ndef \#{sym}=(obj)\n##\#{sym} = obj\nend\n\" unless options[:instance_writer] == false }\n", __FILE__, __LINE__)
end
end
You can get this functionality by including the Ruby Facets gem. Reference the source here:
https://github.com/rubyworks/facets/blob/master/lib/core/facets/cattr.rb
You generally don't need to require all code from the gem. You can selectively require what you want. There are quite a few useful extensions in the gem though.
Related
I have a ruby script for yaml merging as follows
#!/usr/bin/env ruby
require 'yaml'
raise "wrong number of parameters" unless ARGV.length == 2
y1 = YAML.load_file(ARGV[0]).symbolize_keys
y2 = YAML.load_file(ARGV[1]).symbolize_keys
puts y1.merge!(y2).to_yaml
when I execute it:
./test.rb ./src/api/config/config1.yml ./src/api/config/config2.yml
I've got the following error:
./test.rb:5:in `<main>': undefined method `symbolize_keys' for {"root"=>{"cloud.n2"=>{"accessKey"=>"I5VAJUYNR4AAKIZDH777"}}}:Hash (NoMethodError)
Hash#symbolize_keys method comes from activesupport gem (activesupport/lib/active_support/core_ext/hash/keys.rb).
In order to use it, you need to add the following line to your script:
require "active_support"
While the other answers/comments are correct it seems like overkill to require all of ActiveSupport for this. Instead either use:
require 'active_support/core_ext/hash/keys'
Or if you have control over the yml files then just make the keys symbols there and avoid any transformation. For Example
require 'yaml'
yml = <<YML
:root:
:cloud.n2:
:accessKey: "I5VAJUYNR4AAKIZDH777"
YML
YAML.load(yml)
#=> {:root=>{:"cloud.n2"=>{:accessKey=>"I5VAJUYNR4AAKIZDH777"}}}
This does not really the answer your question, but Ruby 2.5.0 introduced Hash#transform_keys (release notes) which also can be used to symbolize keys and is in core Ruby.
{'a' => 1, 'b' => 2}.transform_keys(&:to_sym)
#=> {:a=>1, :b=>2}
There is also a bang version which mutates the hash instead of creating a new one.
As other have already noted, symbolize_keys is an ActiveSupport method. If you are not using ActiveSupport, and/or on a pre-2.5 version of Ruby that does not include transform_keys, you could define it yourself.
class Hash
def transform_keys
return enum_for(:transform_keys) unless block_given?
result = self.class.new
each_key do |key|
result[yield(key)] = self[key]
end
result
end
def transform_keys!
return enum_for(:transform_keys!) unless block_given?
keys.each do |key|
self[yield(key)] = delete(key)
end
self
end
def symbolize_keys
transform_keys{ |key| key.to_sym rescue key }
end
def symbolize_keys!
transform_keys!{ |key| key.to_sym rescue key }
end
end
This is not to say that there are not likely other dependencies on Rails or ActiveSupport that will be required for your script.
So, I'm trying to build a quick console program for my development needs, akin to rails console (I'm using Sinatra + DataMapper + pry).
I run it and launch cat = Category.new(name: 'TestCat', type: :referential). It gives me the following error:
Error: Cannot open "/home/art-solopov/Projects/by-language/Ruby/billy-bones/=" for reading.
What could be the cause of the problem?
console:
#!/usr/bin/env ruby
$LOAD_PATH << 'lib'
require 'pry'
require 'config'
binding.pry
lib/config.rb:
# Configuration files and app-wide requires go here
require 'sinatra'
require 'data_mapper'
require 'model/bill'
require 'model/category'
configure :production do
DataMapper::Logger.new('db-log', :debug)
DataMapper.setup(:default,
'postgres://billy-bones:billy#localhost/billy-bones')
DataMapper.finalize
end
configure :development do
DataMapper::Logger.new($stderr, :debug)
DataMapper.setup(:default,
'postgres://billy-bones:billy#localhost/billy-bones-dev')
DataMapper.finalize
DataMapper.auto_upgrade!
end
configure :test do
require 'dm_migrations'
DataMapper::Logger.new($stderr, :debug)
DataMapper.setup(:default,
'postgres://billy-bones:billy#localhost/billy-bones-test')
DataMapper.finalize
DataMapper.auto_migrate!
end
lib/model/category.rb:
require 'data_mapper'
class Category
include DataMapper::Resource
property :id, Serial
property :name, String
property :type, Enum[:referential, :predefined, :computable]
has n, :bills
# has n, :tariffs TODO uncomment when tariff ready
def create_bill(params)
# A bill factory for current category type
case type
when :referential
ReferentialBill.new params
when :predefined
PredefinedBill.new params
when :computable
ComputableBill.new params
end
end
end
If I substitute pry with irb in the console script, it goes fine.
Thank you very much!
P. S.
Okay, yesterday I tried this script again, and it worked perfectly. I didn't change anything. I'm not sure whether I should remove the question now or not.
P. P. S.
Or actually not... Today I've encountered it again. Still completely oblivious to what could cause it.
** SOLVED **
DAMN YOU PRY!
Okay, so here's the difference.
When I tested it the second time, I actually entered a = Category.new(name: 'TestCat', type: :referential) and it worked. Looks like pry just thinks cat is a Unix command, not a valid variable name.
Not answer to the pry question I just generally hate case statements in ruby.
Why not change:
def create_bill(params)
# A bill factory for current category type
case type
when :referential
ReferentialBill.new params
when :predefined
PredefinedBill.new params
when :computable
ComputableBill.new params
end
end
to:
def create_bill(params)
# A bill factory for current category type
self.send("new_#{type}_bill",params)
end
def new_referential_bill(params)
ReferentialBill.new params
end
def new_predefined_bill(params)
PredefinedBill.new params
end
def new_computable_bill(params)
ComputableBill.new params
end
You could make this more dynamic but I think that would take away from readability in this case but if you'd like in rails this should do the trick
def create_bill(params)
if [:referential, :predefined, :computable].include?(type)
"#{type}_bill".classify.constantize.new(params)
else
#Some Kind of Handling for non Defined Bill Types
end
end
Or this will work inside or outside rails
def create_bill(params)
if [:referential, :predefined, :computable].include?(type)
Object.const_get("#{type.to_s.capitalize}Bill").new(params)
else
#Some Kind of Handling for non Defined Bill Types
end
end
Some popular blog sites typically use square brackets in their URLs but ruby's built-in URI.parse() method chokes on them, raising a nasty exception, as per:
http://redmine.ruby-lang.org/issues/show/1466
I'm trying to write a simple monkey-patch that gracefully handles URLs with the square bracket. The following is what I have so far:
require 'uri'
module URI
def self.parse_with_safety(uri)
safe_uri = uri.replace('[', '%5B')
safe_uri = safe_uri.replace(']', '%5D')
URI.parse_without_safety(safe_uri)
end
alias_method_chain :parse, :safety
end
But when run, this generates an error:
/Library/Ruby/Gems/1.8/gems/activesupport-2.3.8/lib/active_support/core_ext/module/aliasing.rb:33:in alias_method: NameError: undefined method 'parse' for module 'URI'
How can I successfully monkey-patch URI.parse?
alias_method_chain is executed on the module level so it only affects instance methods.
What you have to do is execute it on the module's class level:
require 'uri'
module URI
class << self
def parse_with_safety(uri)
parse_without_safety uri.gsub('[', '%5B').gsub(']', '%5D')
end
alias parse_without_safety parse
alias parse parse_with_safety
end
end
#nil his comment is very helpful, we ended up with the following:
def parse_with_safety(uri)
begin
parse_without_safety uri.gsub(/([{}|\^\[\]\#`])/) {|s| URI.escape(s)}
rescue
parse_without_safety '/'
end
end
I'm learning Ruby (using version 1.8.6) on Windows 7.
When I try to run the stock_stats.rb program below, I get the following error:
C:\Users\Will\Desktop\ruby>ruby stock_stats.rb
stock_stats.rb:1: undefined method `require_relative' for main:Object (NoMethodE
rror)
I have three v.small code files:
stock_stats.rb
require_relative 'csv_reader'
reader = CsvReader.new
ARGV.each do |csv_file_name|
STDERR.puts "Processing #{csv_file_name}"
reader.read_in_csv_data(csv_file_name)
end
puts "Total value = #{reader.total_value_in_stock}"
csv_reader.rb
require 'csv'
require_relative 'book_in_stock'
class CsvReader
def initialize
#books_in_stock = []
end
def read_in_csv_data(csv_file_name)
CSV.foreach(csv_file_name, headers: true) do |row|
#books_in_stock << BookInStock.new(row["ISBN"], row["Amount"])
end
end
# later we'll see how to use inject to sum a collection
def total_value_in_stock
sum = 0.0
#books_in_stock.each {|book| sum += book.price}
sum
end
def number_of_each_isbn
# ...
end
end
book_in_stock.rb
require 'csv'
require_relative 'book_in_stock'
class CsvReader
def initialize
#books_in_stock = []
end
def read_in_csv_data(csv_file_name)
CSV.foreach(csv_file_name, headers: true) do |row|
#books_in_stock << BookInStock.new(row["ISBN"], row["Amount"])
end
end
# later we'll see how to use inject to sum a collection
def total_value_in_stock
sum = 0.0
#books_in_stock.each {|book| sum += book.price}
sum
end
def number_of_each_isbn
# ...
end
end
Thanks in advance for any help.
require_relative doesn't exist in your version of Ruby. You could upgrade Ruby, install the backports gem and require 'backports/1.9.1/kernel/require/relative' but the easiest fix will be to change your require to:
require File.join(File.dirname(__FILE__), 'csv_reader')
Edit:
Back in the days where this question was asked it referred to Ruby 1.8.6 where there was no require_relative. By now Ruby 1.8.6 is outdated and shouldn't be used anymore.
Original:
There is simply no method name require_relative. You can use require there aswell.
The require_relative function is included in an extension project to the Ruby core libraries, found here: http://www.rubyforge.org/projects/extensions
You should be able to install them with gem install extensions.
Then in your code add the following line before the require_relative:
require 'extensions/all'
I have a method that takes a block.
Obviously I don't know what is going to be passed in and for bizarre reasons that I won't go into here I want to print the contents of the block.
Is there a way to do this?
You can do this with Ruby2Ruby which implements a to_ruby method.
require 'rubygems'
require 'parse_tree'
require 'parse_tree_extensions'
require 'ruby2ruby'
def meth &block
puts block.to_ruby
end
meth { some code }
will output:
"proc { some(code) }"
I would also check out this awesome talk by Chris Wanstrath of Github http://goruco2008.confreaks.com/03_wanstrath.html He shows some interesting ruby2ruby and parsetree usage examples.
In Ruby 1.9+ (tested with 2.1.2), you can use https://github.com/banister/method_source
Print out the source via block#source:
#! /usr/bin/ruby
require 'rubygems'
require 'method_source'
def wait &block
puts "Running the following code: #{block.source}"
puts "Result: #{yield}"
puts "Done"
end
def run!
x = 6
wait { x == 5 }
wait { x == 6 }
end
run!
Note that in order for the source to be read you need to use a file and execute the file (testing it out from irb will result in the following error: MethodSource::SourceNotFoundError: Could not load source for : No such file or directory # rb_sysopen - (irb)
Building on Evangenieur's answer, here's Corban's answer if you had Ruby 1.9:
# Works with Ruby 1.9
require 'sourcify'
def meth &block
# Note it's to_source, not to_ruby
puts block.to_source
end
meth { some code }
My company uses this to display the Ruby code used to make carbon calculations... we used ParseTree with Ruby 1.8 and now sourcify with Ruby 1.9.
In Ruby 1.9, you can try this gem which extract the code from source file.
https://github.com/ngty/sourcify
In Ruby 2.5 the following works
puts block.source
In ruby 2.7, using the method_source gem (pry depends on it)
Set.instance_method(:merge).source.display
# =>
def merge(enum)
if enum.instance_of?(self.class)
#hash.update(enum.instance_variable_get(:#hash))
else
do_with_enum(enum) { |o| add(o) }
end
self
end
The repo says it works for procs, but I haven't tested it.