I've spent a certain amount of time looking into the performanceof the regular expression engines in both (some version(s) of)Perl and Python and reading things like Russ Cox's serieson regular expressions . Like a lot of other peopleI've also read a certain amount of general wisdom on regularexpression performance out on the Internet.

Here is what my direct experience has convinced me: I have no realidea how a regular expression engine is going to perform in somesituation unless I measure

As part of thinking about 'web of trust' systems, I've recently cometo think that there are effectively two sorts of identities on theInternet. For lack of a better terminology I will call these 'internal'and 'external'.

An external identity is an identity that is linked to something in theoutside Internet world. In one sense, the identity exists to assert thatthe person behind a series of work is the same person and this new workcomes from the same person as a series of

I have been busy having a somewhat painful learning experience about SAS , especiallybearing on putting SATA disks behind SAS. In my usual way I'm going towrite down what I've learned so that it will stick.

SAS is yet another disk interconnect technology. It came out of SCSI(as opposed to SATA coming out of ATA) and so it is generally morelarge-scale, enterprisey, and costly. You can, at least in theory, useSATA disks in (some) SAS systems.

I was recently reading David Halter's Why Python's dir functionis wrong which points out that dir() on classes and types excludes somevalid attributes from the result (for example, __bases__ ).As it happens, I have a theory about why Python behaves this way.The short version is that it is a heuristic to make dir() moreuseful.

(Note that classes and types are the same thing .From now on I'm going to use 'class'

Someone from outside looking at my environment and what I use and domight think that I'm a Unix purist; after all, I use an odd andlimited shell , a strippeddown and custom desktop environment , and Ipersist in reading my email with MH ( whichis a very Unixy thing in the abstract ) instead of a modernIMAP client. I could go on, but I think you get the general drift.That impression would be a mistake. I am not really a Unix purist.

Oh,

For reasons beyond the scope of this entry I've been thinking aboutadding some CSRF protectionto the comment posting system here (which is the only thing that'sexposed to CSRF attacks). My understanding is that the standardapproach to CSRF protection is to set the same magic number as a cookie and as a hidden formparameter when you initially send the form to the user then rejectform submissions when the two don't match. The problem with this,from my perspective, is that this needs you

In an earlier entry I mentioned that Ifelt that RPM was a better package format in practice than Debian .debs.Today it's time to take a stab at justify this. But to start with, let'stalk about what this entry is not about.

In the old days Debian was superior in practice because the whole aptsoftware suite and ecology had no real equivalent in RPM land. Thosedays are long gone. These days yum is as much as part of the RPMecology as apt is for

Like many Unix people, I have a slowly accumulating drift of dotfiles(and dot-directories) cluttering up my $HOME . It has recently struckme that a certain amount of these dotfiles are in fact a self-inflictedinjury, by which I mean that they don't actually have to be dotfiles in $HOME and I could move them elsewhere if I wanted to. There are twovariants of this injury.

The first variety is where I have simply made a file a dotfile in $HOME out of

As I mentioned in my entry on the physical versus the virtual approachto network drop wiring , we use the physicalwiring approach and I think it's the right approach for us. Today I wantto run down my view of the collection of reasons that make it so.

First off is that physical wiring can be done almost entirely with acollection of inexpensive and relatively small switches, since mostswitches are only for a single VLAN. Virtual wiring basically demandsbig switches with a lot of ports so that you can