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Playing With Ruby Metaprogramming

Posted: February 25th, 2010 | Author: gozali | Filed under: Programming, Ruby | Tags: , | 6 Comments » 
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class Array
  def remove(*args)
    string_params = ""
    args.each do |arg_item|
      string_params += arg_item
    end   
    flatten.collect { |k| k.delete string_params}
  end
 
  def repeat(int)
    initial_array = collect { |j| j.to_s.split * int}
    initial_array.flatten
  end
end
rb(main):001:0> require 'meta-test.rb'
=> true
irb(main):002:0> ["one", "two", "three"].repeat(3) 
=> ["one", "one", "one", "two", "two", "two", "three", "three", "three"]
irb(main):003:0>
 
irb(main):003:0> %w{one two three four five six seven eight nine ten}.remove("i","o") 
=> ["ne", "tw", "three", "fur", "fve", "sx", "seven", "eght", "nne", "ten"]

Metaprogramming with Ruby is fun, isn’t it? :)

Rails Tips : Prawnto PDF Generator Dynamic File Name

Posted: December 29th, 2009 | Author: gozali | Filed under: Programming, Rails, Ruby, Work | Tags: , , , , | 1 Comment »

I was getting stuck how to generate dynamic file name for prawn generated pdf file, because there’s lack of example and document here http://cracklabs.com/prawnto/demos

What is Prawnto? Prawnto is is a rails plugin leveraging the new prawn library to produce compiled pdf views, as for me i’m using it for custom reporting tools.

OK, let’s getting back to the problem, what should you do is place prawnto definition in your method rather than in controller’s callbacks :

# /app/controllers/transactions_controller.rb

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def show
    prawnto :prawn => { :page_size => 'A4',
                                     :left_margin => 40,
                                     :right_margin => 30,
                                     :top_margin => 40,
                                     :bottom_margin => 30},
                                     :filename => "invoice_#{@transaction.id}_customer_#{@transaction.customer_id}.pdf"
    render :layout => false
end

# /app/views/transactions/show.pdf.prawn

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<%= link_to "Generate PDF", transaction_url(transaction.id, :format => 'pdf') %>

Hope this is useful, cheers :)

Ruby Tips : Mengubah Isi Array Menjadi Tipe Data Tertentu

Posted: December 15th, 2009 | Author: gozali | Filed under: Programming, Ruby | Tags: , , | 4 Comments »

Sebagai contoh kita ingin menggabungkan dua buah Array dengan elemen yang bervariasi, misalnya String dan Integer dan membuang elemen yang duplicated.

Ilustrasinya sebagai berikut :

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x = [1, 2, 3, 4]
y = ["1", "2", "3", 5]

Array x memiliki elemen dengan tipe data Integer sedangkan Array y memiliki String dan Integer yang sebenarnya jika String tersebut diubah tipe datanya menjadi Integer akan memiliki elemen yang hampir sama dengan Array x. Lalu bagaimana cara agar ketika kedua Array tersebut digabungkan kita mendapatkan Array dengan data yang unik?

Caranya sangat sederhana dan cukup satu baris saja di Ruby :
Dari String ke Integer

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irb(main):003:0> z = (x+ y).flatten.collect { |i| i.to_i } 
=> [1, 2, 3, 4, 1, 2, 3, 5]
irb(main):004:0> z.uniq
=> [1, 2, 3, 4, 5]

Dari Integer ke String :

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irb(main):005:0> z = (x+ y).flatten.collect { |i| i.to_s }
=> ["1", "2", "3", "4", "1", "2", "3", "5"]
irb(main):006:0> z.uniq
=> ["1", "2", "3", "4", "5"]

Atau bahkan Float

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irb(main):007:0> z = (x+ y).flatten.collect { |i| i.to_f }
=> [1.0, 2.0, 3.0, 4.0, 1.0, 2.0, 3.0, 5.0]
irb(main):008:0> z.uniq
=> [1.0, 2.0, 3.0, 4.0, 5.0]

Demikian, semoga bermanfaat :)

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