Python: Select from True/False

I just ran across this neat technique while reading wxPython in Action- A common operation is to output a string based on some expression being True or False. Being an assembly programmer at heart I usully code it as something like this:

if borked:
 print "Its Borked"
else:
 print "Its not Borked Yet"

In 'C' you can do this:

borked ? "Its Borked" : "Its not Borked Yet"

An alternative way in Python is to do it like this:

borked and "Its Borked" or "Its not Borked Yet"

The expression is evaluated from left to right and it returns the result of the and if both are true, or the result of the or if the and fails. In Python instead of returning True for 'borked and "Its Borked" it returns the 2nd object, a string in this case, which is exactly what you want if borked is true. When it is false it goes on to the or expression and returns "Its not Borked Yet"

Productivity for Programmers, #1: Trusted Systems

Bob Walsh and Matt Cornell have an excellent post over at MyMicroISV. They talk about 5 systems that every productive programmer needs to have in their toolbox:

• Task System
• Decision Logs
• Version Control
• Code Snippets
• Your Bugs

Personally, I use a combination of Trac, Subversion and Gtodo.

This is the information I've been waiting for - NIST is going to have a competion for a new secure hashing standard. For a year or so there has been information that the SHA-1 hash has been 'broken', I have been waiting for Bruce Schneier's take on the issue:

The hash function you're most likely to use routinely is SHA-1. Invented by the National Security Agency, it's been around since 1995. Recently, though, there have been some pretty impressive cryptanalytic attacks against the algorithm. The best attack is barely on the edge of feasibility, and not effective against all applications of SHA-1. But there's an old saying inside the NSA: "Attacks always get better; they never get worse." It's past time to abandon SHA-1.

You can read the rest of his essay from Wired here at his blog.

Secure Remote Filesystems

Accessing files on remote systems can sometimes be a big pain in the ass (BPITA). You can use Samba to mount filesystems, but that means setting up a Samba server on the remote system and being susceptible to security problems. There is an alternative, called SSHfs that uses SSH to mount the remote filesystem as if it were a local directory.

In Ubuntu it is easy to get working:

sudo apt-get install sshfs
sudo joe /etc/modules
Add fuse on a line by itself
sudo modprobe fuse (only needed to get it loaded now)
sudo gpasswd -a username fuse
newgrp fuse
mkdir ./mnt/remote
sshfs user@remote.system: ./mnt/remote/

Now your remote account's files are accessible right there on the local system, via a secure link. This works for the MAC as well, if you install MACfuse and Secure Remote Disk.

Unmount the remote filesystem using the unmount command:

fusermount -u ./mnt/remote

This is better than Samba because you are using secure link to transfer the data, it is less complicated and therefore less likely to be compromised than Samba. Building on top of things that do 'just 1 thing' is the Unix way and is a large part of why Unix systems and programming practices are more secure and more flexible than those you see with primarily GUI centric systems.

wxPython

Back in July I wrote that I had settled on pyGTK as the cross-platform development tool for me. Well, I've change my mind a little. With pyGTK you don't get the native 'look-and-feel' on other systems like Windows and MAC. This isn't a problem for me, but for normal users it makes the program appear amateur. Good news, though! The wxWidgets project provides a cross platform C++ environment that uses the native widgets for each platform. And, there is a python project, wxPython, that integrates nicely with it.

So, now I can develop cross platform applications, using my favorite language (Python) and they will look like native applications, keeping the natives happy.