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Tuesday, July 26, 2011

One of Those Things

Check out this question on Stack Overflow: "Python: replace a string by a float in txt file".

The question is confusing, but it appears to be a longish and confused description of simple formatting or template substitution.  It's hard to be sure, but it sounds like one of Those Things™ (TT).

Most of Those Things (TT) are standard problems with standard solutions.  Until you've seen a lot TT's, it seems like your problem is unique and special.  It's hard to see TT's for what they are.

In this case, the problem appears to be solved by Python's string.Template class with minor modifications.  The documentation for customizing string.Template isn't clear, so here's an example.

from string import Template
class MyTemplate( Template ):
    delimiter= '@'
    pattern= r"@(?P<escaped>@)|@(?P<named>[_a-z][_a-z0-9]*)@|@(?P<braced>[_a-z][_a-z0-9]*)@|@(?P<invalid>)"

That appears to be the standard solution to the standard problem.  Define a new delimiter ('@') and some slightly different delimiter parsing rules and away you go.

This can be used as follows to replace any '@x@' variables in any template file.  What's important is that very little actual code is needed, since it's one of Those Things that's already been solved.

with open( 'a.txt', 'r' ) as source:
    t = MyTemplate(
    result= t.substitute( x=15 )
    print result

Thursday, July 21, 2011

Spam Email Footers

I don't want the spamilicious email.  I'm trying to actually unsubscribe.

The footer says "If you are not the intended recipient, you are hereby notified that any dissemination, distribution or copying of any information contained in or attached to this communication is strictly prohibited. If you have received this message in error, please notify the sender immediately and delete the material from any computer."

I don't feel like the intended recipient because it's just irrelevant junk.  Perhaps you should not have disseminated, distributed, copied or sent me this.  Wouldn't that have been simpler? Keep it to yourself?

I also think I've received the message in error.  Since I don't want the damn thing. And that means that I have to delete it?  Why can't you stop sending it?  Wouldn't that be simpler for both of us?

Monday, July 18, 2011

757 Python User's Group Meetup

Wednesday night.  At 757 Labs.  Be there.

Here's the details on

Lacking any other agenda, I'll do some more presentation on the supreme coolness of Django.

Tuesday, July 12, 2011

I almost wet myself

Someone sent me this: "“Building Skills in Python” – Steven F. Lott".

I had a vague idea that this book would get some traction.  This response was surprising.  I guess I should get to work on the upgrades.  And focus on the "no-nonsense" comment.

Thursday, July 7, 2011

Security Vulnerabilities

Just saw this for the first time today:

I'd always relied on this:

Both are really good lists of security vulnerabilities.

I once had to listen to a DBA tell me that "we don't know what we don't know" as a way of saying that there was no way to be sure that a web app was "secure".  That comment lead the project manager to go  through the classic "risk exposure" exercise (and hours of discussion) to determine that security mattered.  We defined the risks, the costs and the probability of occurrence so that we could document all kinds of potential exposures or something.

Instead of hand-wringing, these kinds of simple lists of the common vulnerabilities provides actionable steps for design, code, test and audit of operations.  Further, they guide selection, configuration and operation of web server technology to assure that the vulnerabilities are addressed.