How to split() strings of indefined item count to Python variables elegantly?

A common problem for  (space) separated string parsing is that there are a number of fixed items followed by some amount of optional items. You want to extract parsed values to Python variables and initialize optional values with None if they are missing.

E.g. we have option format description string with 2 or 3 items value1 value2 [optional value]

s = "foo bar" # This is a valid example option string
s2 = "foo bar optional" # This is also, with one optional item

Usually we’d like to parse this so that non-existing options are set to None. Traditonally one does Python code like below:

# Try get extration and deletion
parts = s.split(" ")
value1 = parts[0]
value2 = parts[1]
if len(parts) >= 3:
    optional_value = parts[2]
    optionanl_value = None

However, this looks little bit ugly, considering  if there would always be just two options one could write:

value1, value2 = s.split(" ")

When the number of optional options grow, the boiler-plate code starts annoy greatly.

I have been thinking how to write a split() code to parse options with non-existing items to be set None. Below is my approach for a string with total of 4 options of which any number can be optional.

parts = s.split(" ", 4) # Will raise exception if too many options 
parts += [None] * (4 - len(parts)) # Assume we can have max. 4 items. Fill in missing entries with None.
value1, value2, optional_value, optional_value2 = parts

Any ideas for something more elegant?

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ssh-copy-id for OSX

ssh-copy-id is a handy shell script which allows you to easily copy your public key to a remote server, so that you don’t need type in password every time you take SSH connection into that box. Ubuntu and the latest Linux distros ship ssh-copy-id with the ssh client installation. However, for OSX you need to manually drop this little script into your /usr/bin.

The usage is simple. Just run:


to copy your public SSH key to After that


shoud ask no password.

Working installation instructions for ssh-copy-id on OSX are in Chris Pitzer’s blog.

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Why C# / Javascript will be allowed and Flash won’t be as App Store programming language

All the Flash developers of the world wet their pants on 8th April 2010 when Apple announced that Flash based application won’t be approved in the Apple’s App Store. This essentially destroyed the easy opportunity to monetize existing Flash development skills and the huge Adobe expansion potential into mobile markets, pissing a lot of folks who had bet on Adobe’s technology, leading developers’ rage on Internet forums.  Bad news for those who had already building iPhone apps on Flash CS5 even before it was released…

Unfortunately it was not only Adobe and Flash who got in the line of fire: popular frameworks like Appcelerator, Unity 3D and Monotouch apps are theoretically excluded to enter App Store by the new developer agreement which states that the original source code of the application must be C, C++, Objective-C or WebKit/Javascript.

I belive Apple does not hate certain programming languages. Apple does not either want to force you to use their development tools. Only by understanding what Apple really meant with the infamous 3.3.1  clause in the developer agreement, we can start building a bridge to get MonoTouch et. al. to be Apple’s favorites again.

1. History of Flash (Lite)

Adobe (Macromedia) and Flash have been into mobile business far before iPhone was published. The thing is called Flash Lite run-time. It runs on billions of phones.

The problem of Flash Lite is that it does not very well integrate with its host environment. It does not even have so simple user interface component as a “menu” out of the box. Which means that every developer must create their own menu implementation. Which means that there exist hundreds of shitty Flash Lite menu implementations out there, each behaving differently and each not resembling the native menu component. This is not a very nice thing if you consider the user experience of the application and iPhone  is all about user experience. Note that this is not so big thing for games, as games have radically different user experience anyway.

Flash does not communicate with its host platform either. You wouldn’t be able to access native API features even if you fully controlled the deployment environment of Flash application, as Flash is a binary blob into which you cannot plug-in more parts. There even exists a product for mobile Flash whose sole purpose is circumvent the limitations of  Flash by using a localhost TCP/IP socket connection and a native server application. If developers choose Flash they choose to lock themselves into Flash and what Adobe gives for them.

This crippling of your platform potential with Flash is not limited to Flash Lite and mobile. I have personal experiences from a project done with Adobe Air for Windows. We wisely chose Adobe Air as a desktop application development platform, because it would guarantee the future portability of our code. However, this nice idea did not really interest in the point when we noticed that we e.g. couldn’t control how File Open dialogs behave (file mask, remember start folder, etc.), severely reducing the user experience of the application.

So, Steve Jobs definitely is on something when he says “intermediary translation or compatibility layer” is bad for your platform.

Note that the same limitation concerns Java ME also. Desktop Java has JNI interface for building extensions, but mobile Java doesn’t.

2. How other frameworks differ from Flash

Let’s take a MonoTouch for example. MonoTouch is Novell’s open source Mono project based development tool which allows you to create iPhone applications in C# language. Compared to Objective C, development using MonoTouch  has several advantages for certain audience: you don’t need to learn new programming language, C# is closer to traditional Java/C++ languages than Objective-C, you can leverage the full potential of existing C# ecosystem out there, the standard library has more functionality and of course, it is easier to port the core of the application from a platform to another.

Note that the porting part concerns core i.e. application logic only. MonoTouch does not try to separate you from Apple’s platform. It does not reinvent platform services or user interface building blocks, or force something like Windows user interface into your shiny iPhone. In fact, MonoTouch seamlessly integrates with Apple’s platform. You even need to use Apple’s own Interface Builder tool to create user interfaces, which will be exposed to MonoTouch’s C# code. Binding with native API is breeze: below ten lines of code guaranteeing that whenever Apple releases a new platform feature it will be instantly available for all MonoTouch developers.

MonoTouch embraces the platform. You can pick Objective C or C# depending on taste. The resulting source code is similar in idea, different in syntax. There is no “compatibility layer” so to say. Not even technically, as C# is compiled to native ARM binary. There is no way how a person could distinguish a MonoTouch application from an application build using Objective-C.

3. Open source philosophy and platforms

Appcelerator, PhoneGap and other open source / Javascript frameworks are also protected from Apple’s wrath. They are open source which means that you can tap the full potential Apple’s development platform as long as someones writes a little binding code. Also, they try to use native look and feel and components as much as possible, just to make the applications slick. The frameworks do not have conflicting interest with Apple; the frameworks provide portability to a certain point, but they do this respecting their master.

Flash does not enjoy this freedom; developers can’t change Flash or venture outside Flash’s sandbox.

4. The Future

There is no point of technically counter App Store’s developer agreement, like saying “hey I’ll just compile all my Flash source code to C so it is C code.” It’s Apple’s game. Apple can do anything they wish and they can also change the developer agreement. So when Apple sees something happening in its ecosystem which might damage it, it simply pulls the rug under your feet again. But Apple can also change the agreement in a positive way. PhoneGap has already went through process of becoming App Store approved framework once. I hope that development communities will not burn its bridges with Apple, but try to communicate this matter with a meaningful manner and come to a development agreement resolution based on ideas given in this blog post. Below is my proposition (IANAL. It is left to the reader to come up with something smarter):

3.3.1 — Applications may only use Documented APIs in the manner prescribed by Apple and must not use or call any private APIs. Applications must be written using Apple’s guidelines and best practices to express Apple’s intend how the application should behave.

iPhone is not a monopoly. You are free to build and run your Flash application on a device like N900 on any day and sell it in Nokia’s OVI store. If this is a problem for your business then maybe you should reconsider your business model to be less iPhone centric and promote heterogenicity of mobile platforms and application stores.

Until Flash is fixed so that you can mix-in native code, instead of it being a barrier between the expression and the hosting platform, I find it unlikely any company based their reputation around the user experience would allow Flash on their platform.

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