クレジットカード番号には法則があり、先頭6桁でカードの種類を識別、分類することができる。
詳細はISO/IEC 7812で規定されている。
ISO/IEC 7812 - Wikipedia https://ja.wikipedia.org/wiki/ISO/IEC_7812
先頭の6桁を銀行識別番号（Bank Identification Number、略称:BIN）ないしは発行者識別番号（Issuer Identification Number、略称:IIN）と呼び、この先頭6桁でカード発行会社(イシュア、issuer)が判るようになっている。
| class Integer | |
| N_BYTES = [42].pack('i').size | |
| N_BITS = N_BYTES * 16 | |
| MAX = 2 ** (N_BITS - 2) - 1 | |
| MIN = -MAX - 1 | |
| end | |
| p Integer::MAX #=> 4611686018427387903 | |
| p Integer::MAX.class #=> Fixnum | |
| p (Integer::MAX + 1).class #=> Bignum |
| # Put this in your ~/.(bash|zsh|*)rc file | |
| # Usage: apm bundle | |
| # For an example Atomfile, look here: https://github.com/bahlo/dotfiles/tree/master/atom.symlink | |
| function apm() { | |
| REAL_APM="/usr/local/bin/apm" | |
| if [[ $# -eq 0 ]]; then | |
| $REAL_APM $1 | |
| echo "<command> can also be bundle." | |
| echo |
| # Call scopes directly from your URL params: | |
| # | |
| # @products = Product.filter(params.slice(:status, :location, :starts_with)) | |
| module Filterable | |
| extend ActiveSupport::Concern | |
| module ClassMethods | |
| # Call the class methods with names based on the keys in <tt>filtering_params</tt> | |
| # with their associated values. For example, "{ status: 'delayed' }" would call |
| <!DOCTYPE html> | |
| <html> | |
| <head> | |
| <meta charset="utf-8"> | |
| <title>Building a router</title> | |
| <script> | |
| // Put John's template engine code here... | |
| (function () { | |
| // A hash to store our routes: |
| #!/bin/bash | |
| # Set the ROOM_ID & AUTH_TOKEN variables below. | |
| # Further instructions at https://www.hipchat.com/docs/apiv2/auth | |
| ROOM_ID=XXX | |
| AUTH_TOKEN=XXX | |
| MESSAGE="Hello world!" | |
| curl -H "Content-Type: application/json" \ |
| drb.rb | |
| #!/usr/local/bin/ruby | |
| =begin | |
| Tiny distributed Ruby --- dRuby | |
| DRb --- dRuby module. | |
| DRbProtocol --- Mixin class. | |
| DRbObject --- dRuby remote object. | |
| DRbConn --- | |
| DRbServer --- dRuby message handler. | |
| =end |
