When using Tempfile Ruby is creating a file with a thread-safe and inter-process-safe name. I only need a file name in that way.
I was wondering if there is a more straight forward approach way than:
t = Tempfile.new(['fleischwurst', '.png'])
temp_path = t.path
t.close
t.unlink
Dir::Tmpname.create
You could use Dir::Tmpname.create. It figures out what temporary directory to use (unless you pass it a directory). It's a little ugly to use given that it expects a block:
require 'tmpdir'
# => true
Dir::Tmpname.create(['prefix-', '.ext']) {}
# => "/tmp/prefix-20190827-1-87n9iu.ext"
Dir::Tmpname.create(['prefix-', '.ext'], '/my/custom/directory') {}
# => "/my/custom/directory/prefix-20190827-1-11x2u0h.ext"
The block is there for code to test if the file exists and raise an Errno::EEXIST so that a new name can be generated with incrementing value appended on the end.
The Rails Solution
The solution implemented by Ruby on Rails is short and similar to the solution originally implemented in Ruby:
require 'tmpdir'
# => true
File.join(Dir.tmpdir, "YOUR_PREFIX-#{Time.now.strftime("%Y%m%d")}-#{$$}-#{rand(0x100000000).to_s(36)}-YOUR_SUFFIX")
=> "/tmp/YOUR_PREFIX-20190827-1-wyouwg-YOUR_SUFFIX"
File.join(Dir.tmpdir, "YOUR_PREFIX-#{Time.now.strftime("%Y%m%d")}-#{$$}-#{rand(0x100000000).to_s(36)}-YOUR_SUFFIX")
=> "/tmp/YOUR_PREFIX-20190827-1-140far-YOUR_SUFFIX"
Dir::Tmpname.make_tmpname (Ruby 2.5.0 and earlier)
Dir::Tmpname.make_tmpname was removed in Ruby 2.5.0. Prior to Ruby 2.4.4 it could accept a directory path as a prefix, but as of Ruby 2.4.4, directory separators are removed.
Digging in tempfile.rb you'll notice that Tempfile includes Dir::Tmpname. Inside you'll find make_tmpname which does what you ask for.
require 'tmpdir'
# => true
File.join(Dir.tmpdir, Dir::Tmpname.make_tmpname("prefix-", nil))
# => "/tmp/prefix-20190827-1-dfhvld"
File.join(Dir.tmpdir, Dir::Tmpname.make_tmpname(["prefix-", ".ext"], nil))
# => "/tmp/prefix-20190827-1-19zjck1.ext"
File.join(Dir.tmpdir, Dir::Tmpname.make_tmpname(["prefix-", ".ext"], "suffix"))
# => "/tmp/prefix-20190827-1-f5ipo7-suffix.ext"
Since Dir::Tmpname.make_tmpname was removed in Ruby 2.5.0, this one falls back to using SecureRandom:
require "tmpdir"
def generate_temp_filename(ext=".png")
filename = begin
Dir::Tmpname.make_tmpname(["x", ext], nil)
rescue NoMethodError
require "securerandom"
"#{SecureRandom.urlsafe_base64}#{ext}"
end
File.join(Dir.tmpdir, filename)
end
Since you only need the filename, what about using the SecureRandom for that:
require 'securerandom'
filename = "#{SecureRandom.hex(6)}.png" #=> "0f04dd94addf.png"
You can also use SecureRandom.alphanumeric
I found the Dir:Tmpname solution did not work for me. When evaluating this:
Dir::Tmpname.make_tmpname "/tmp/blob", nil
Under MRI Ruby 1.9.3p194 I get:
uninitialized constant Dir::Tmpname (NameError)
Under JRuby 1.7.5 (1.9.3p393) I get:
NameError: uninitialized constant Dir::Tmpname
You might try something like this:
def temp_name(file_name='', ext='', dir=nil)
id = Thread.current.hash * Time.now.to_i % 2**32
name = "%s%d.%s" % [file_name, id, ext]
dir ? File.join(dir, name) : name
end
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.
What is the correct way to view the output of the puts statements below? My apologies for such a simple question.... Im a little rusty on ruby. github repo
require 'active_support'
require 'active_support/core_ext'
require 'indicators'
my_data = Indicators::Data.new(Securities::Stock.new(:symbol => 'AAPL', :start_date => '2012-08-25', :end_date => '2012-08-30').output)
puts my_data.to_s #expected to see Open,High,Low,Close for AAPL
temp=my_data.calc(:type => :sma, :params => 3)
puts temp.to_s #expected to see an RSI value for each data point from the data above
Maybe check out the awesome_print gem.
It provides the .ai method which can be called on anything.
An example:
my_obj = { a: "b" }
my_obj_as_string = my_obj.ai
puts my_obj_as_string
# ... this will print
# {
# :a => "b"
# }
# except the result is colored.
You can shorten all this into a single step with ap(my_obj).
There's also a way to return objects as HTML. It's the my_obj.ai(html: true) option.
Just use .inspect method instead of .to_s if you want to see internal properties of objects.
I have a YAML config file where I want to include specific ruby class/module constants instead of the actual value.
For example, instead of putting "loglevel: 0" in the config file, I want "loglevel: Logger::DEBUG".
Is there a way to have YAML decode or resolve a class or module constant like Logger::DEBUG?
This is what I've been playing with, but looking at the psych ruby code, I don't see anything that might support this.
config.yml
loglevel: !ruby/class:fixnum Logger::DEBUG
In irb
irb> require 'logger'
irb> config = YAML.load_file('config.yml')
config['loglevel'] contains "Logger::DEBUG" as a String instead of the actual value.
I can do an eval on it like so:
irb> p eval config['loglevel']
0
==> 0
I'm just wondering if there's a way to have YAML eval it? I'm okay with doing it in my code after doing a YAML load, but I wanted to make sure I left no stone unturned in my, what has turned into a lengthy, quest ;-).
Not sure of a YAML way, but best not to use eval...
In Ruby 2+
Object.const_get 'Logger::DEBUG'
Or the old school
def const_lookup const_name
const_name.split('::').inject(Object) do |rec, name|
rec.const_get(name)
end
end
const_lookup 'Logger::DEBUG'
Looks like you can do it for classes/modules but not their constants
2.0.0-p247 :046 > YAML.load("!ruby/class 'String'")
=> String
2.0.0-p247 :047 > YAML.load("!ruby/class 'String'").class
=> Class
2.0.0-p247 :065 > YAML.load("!ruby/class 'Logger'")
=> Logger
I am writing some Ruby code, not Rails, and I need to handle something like this:
found 1 match
found 2 matches
I have Rails installed so maybe I might be able to add a require clause at the top of the script, but does anyone know of a RUBY method that pluralizes strings? Is there a class I can require that can deal with this if the script isn't Rails but I have Rails installed?
Edit: All of these answers were close but I checked off the one that got it working for me.
Try this method as a helper when writing Ruby, not Rails, code:
def pluralize(number, text)
return text.pluralize if number != 1
text
end
Actually all you need to do is
require 'active_support/inflector'
and that will extend the String type.
you can then do
"MyString".pluralize
which will return
"MyStrings"
for 2.3.5 try:
require 'rubygems'
require 'active_support/inflector'
should get it, if not try
sudo gem install activesupport
and then the requires.
Inflector is overkill for most situations.
def x(n, singular, plural=nil)
if n == 1
"1 #{singular}"
elsif plural
"#{n} #{plural}"
else
"#{n} #{singular}s"
end
end
Put this in common.rb, or wherever you like your general utility functions and...
require "common"
puts x(0, 'result') # 0 results
puts x(1, 'result') # 1 result
puts x(2, 'result') # 2 results
puts x(0, 'match', 'matches') # 0 matches
puts x(1, 'match', 'matches') # 1 match
puts x(2, 'match', 'matches') # 2 matches
I personally like the linguistics gem that is definitely not rails related.
# from it's frontpage
require 'linguistics'
Linguistics.use :en
"box".en.plural #=> "boxes"
"mouse".en.plural #=> "mice"
# etc
This works for me (using ruby 2.1.1 and actionpack 3.2.17):
~$ irb
>> require 'action_view'
=> true
>> include ActionView::Helpers::TextHelper
=> Object
>> pluralize(1, 'cat')
=> "1 cat"
>> pluralize(2, 'cat')
=> "2 cats"
require 'active_support'
require 'active_support/inflector'
inf = ActiveSupport::Inflector::Inflections.new
to get the inflector, not sure how you use it
my solution:
# Custom pluralize - will return text without the number as the default pluralize.
def cpluralize(number, text)
return text.pluralize if number != 1
return text.singularize if number == 1
end
So you can have 'review' returned if you call cpluralize(1, 'reviews')
Hope that helps.
I've defined a helper function for that, I use it for every user editable model's index view :
def ovyka_counter(array, name=nil, plural=nil)
name ||= array.first.class.human_name.downcase
pluralize(array.count, name, plural)
end
then you can call it from the view :
<% ovyka_counter #posts %>
for internationalization (i18n), you may then add this to your locale YAML files :
activerecord:
models:
post: "Conversation"
This is a newbie question as I am attempting to learn Ruby by myself, so apologies if it sounds like a silly question!
I am reading through the examples of why's (poignant) guide to ruby and am in chapter 4. I typed the code_words Hash into a file called wordlist.rb
I opened another file and typed the first line as require 'wordlist.rb' and the rest of the code as below
#Get evil idea and swap in code
print "Enter your ideas "
idea = gets
code_words.each do |real, code|
idea.gsub!(real, code)
end
#Save the gibberish to a new file
print "File encoded, please enter a name to save the file"
ideas_name = gets.strip
File::open( 'idea-' + ideas_name + '.txt', 'w' ) do |f|
f << idea
end
When I execute this code, it fails with the following error message:
C:/MyCode/MyRubyCode/filecoder.rb:5: undefined local variable or method `code_words' for main:Object (NameError)
I use Windows XP and Ruby version ruby 1.8.6
I know I should be setting something like a ClassPath, but not sure where/how to do so!
Many thanks in advance!
While the top-level of all files are executed in the same context, each file has its own script context for local variables. In other words, each file has its own set of local variables that can be accessed throughout that file, but not in other files.
On the other hand, constants (CodeWords), globals ($code_words) and methods (def code_words) would be accessible across files.
Some solutions:
CodeWords = {:real => "code"}
$code_words = {:real => "code"}
def code_words
{:real => "code"}
end
An OO solution that is definitely too complex for this case:
# first file
class CodeWords
DEFAULT = {:real => "code"}
attr_reader :words
def initialize(words = nil)
#words = words || DEFAULT
end
end
# second file
print "Enter your ideas "
idea = gets
code_words = CodeWords.new
code_words.words.each do |real, code|
idea.gsub!(real, code)
end
#Save the gibberish to a new file
print "File encoded, please enter a name to save the file"
ideas_name = gets.strip
File::open( 'idea-' + ideas_name + '.txt', 'w' ) do |f|
f << idea
end
I think the problem might be that the require executes the code in another context, so the runtime variable is no longer available after the require.
What you could try is making it a constant:
CodeWords = { :real => 'code' }
That will be available everywhere.
Here is some background on variable scopes etc.
I was just looking at the same example and was having the same problem.
What I did was change the variable name in both files from code_words to $code_words .
This would make it a global variable and thus accesible by both files right?
My question is: wouldn't this be a simpler solution than making it a constant and having to write CodeWords = { :real => 'code' } or is there a reason not to do it ?
A simpler way would be to use the Marshal.dump feature to save the code words.
# Save to File
code_words = {
'starmonkeys' => 'Phil and Pete, those prickly chancellors of the New Reich',
'catapult' => 'chucky go-go', 'firebomb' => 'Heat-Assisted Living',
'Nigeria' => "Ny and Jerry's Dry Cleaning (with Donuts)",
'Put the kabosh on' => 'Put the cable box on'
}
# Serialize
f = File.open('codewords','w')
Marshal.dump(code_words, f)
f.close
Now at the beginning of your file you would put this:
# Load the Serialized Data
code_words = Marshal.load(File.open('codewords','r'))
Here's the easy way to make sure you can always include a file that's in the same directory as your app, put this before the require statement
$:.unshift File.dirname(__FILE__)
$: is the global variable representing the "CLASSPATH"