7fff – think max value

Good example of antiquity of some Core Ruby classes

A common pattern in Ruby is to call .to_s on an object when you want a String, even if the object itself might be a String. So, e.g., if you are getting NoMethodErrors on nils when you need a String, you might call .to_s to convert that nil into a String (”).

Well, you might want to do the same thing to convert Floats to BigDecimals. But guess what? BigDecimal doesn’t include a .to_d method! Oops. The BigDecimal class must be so old that this idiom hadn’t evolved.

Ruby inherited callback runs before subclass is loaded

Harrumph.

I wanted to call a class method on a subclass when the base class’s inherited callback is triggered.

But it doesn’t work, because the subclass isn’t loaded when this callback is triggered.

So the following doesn’t work (’boo’ prints instead of ‘foo’):

class Base
  def self.permalink
    'boo'
  end
  def self.inherited(c)
    puts "permalink: #{c.permalink}"
  end
end

class C < Base
  def self.permalink
    'foo'
  end
end

You may be able to get what you want by forcing the class to load with Class.new:

class Base
  def self.permalink
    'boo'
  end
  def self.inherited(c)
    puts "permalink: #{c.permalink}"
  end
end

C = Class.new(Base) do
  def self.permalink
    'foo'
  end
end

Nice post at Geezeo regarding BeatThat!

Geezeo — the community-driven personal finance site — did a nice blog post on our product BeatThat!

http://blog.geezeo.com/2009/03/beat-that/

DNS failover: Short TTL vs Multiple A Records?

Note to self:

Apparently the reason people do round-robin DNS with multiple A records is because Internet Explorer retires a bad IP better when the A Record disappears vs. the TTL expiring (worse case for the latter: 28 minutes!).

http://www.netwidget.net/books/apress/dns/info/failover.html

Know your compact fluorescent bulbs

Here’s a great post by my colleague Tom that explains which compact fluorescent bulbs are good:

http://fivepercent.us/2008/09/09/cfl-bulb-review-recommended-cfl-bulbs-to-replace-incandescent/

Managing Two Network Providers: Using a PePlink Balance 30

At work we’ve been a Verizon customer for phone and network. We use a Cisco 800 Series router which gives us wireless and VPN. It has a horrible Java applet interface which is so bad I can’t recommend that router. In any case, we were saturating our bandwidth through this router, and everyone was being driven crazy by the effect on our network when someone would hog up the traffic when deploying software (mostly big transfers from Subversion using ssh — our Subversion server is on this office LAN managed by the Cisco router).

Now we’re all software developers. We’re a tiny company and don’t have anyone to manage our IT; we do it ourselves, and we have rather a lot of equipment and a simple but non-trivial network. Through the goodwill of friends and former colleagues we’ve gotten some advice, but, really, it’s not what we’re good at.

Recently we decided we wanted to augment our Verizon drop with a 2nd drop from Comcast. Comcast has some good deals providing a decent amount of bandwidth. So we bought the drop.

Now how to integrate this into our existing network? With the minimum amount of screwing around? Basically we wanted to leave the Cisco and its VPN alone. We also wanted the office traffic to go via the Comcast drop whenever possible.

This sounds easy, but it’s not. There are a lot of expensive devices that can help you manage “quality of service,” but, really, we wanted something cheap and easy.

After rather a lot of research we settled on the PePlink Balance 30. [Buy from Amazon]

It’s about the size of a conventional home router. It provides for 3 WAN links. So, typically, you would plug Verizon into one WAN port, Comcast into the second, and perhaps — if you have access to it — some free wireless network into the third. In other words, you want to provide to your office multiple ways to get to the outside world in case something goes down.

In our cast, we plugged the Cisco router into one WAN port, the cable from the Comcast modem into the other.

The next step was some custom routing rules. Basically we said that all traffic for the network and VPN managed by the Cisco should go there; and everything else to Comcast.

So far it seems to work great.

The device provides good stats showing WAN utilization, and we’re getting what we want. Some traceroutes look funny (like they’re going via the VPN), but I hope to have that fixed up pretty soon now.

There’s a review out there from SmallNetBuilder.