…and then there were two (posts)

Having survived another day at work, I’ve now gotten round to writing the final few things I missed off this mornings blog post.

One thing I forgot to mention this morning was that, although MSSQL deleted over 1,000 records from a table by a cascaded delete, the output says “4 rows affected” as only four were deleted from the first table. If a higher number had been reported anywhere in the output it might have allerted to us that there was a problem earlier than the customer calling support because their site no longer functioned correctly.

Rant aside, since my last blog post (in May, this is just an extension of this morning’s) my Grandfather, who was formerly a Commando and then a coal miner, died. He’d been ill for sometime but we did not expect him to die quite so suddenly. Fortunately he died peacfully, in A&E where he’d been taken after coughing up some blood at home.

Yesterday Pete wrote about a document on maintainable code he found at work. The document makes some very good points for writing “maintainable code”. However I would dispute the suggestion that “Every function should be most 20 lines of code”. The rule where I work is that a function should be the length necessary to perform its given task, no more and no less. Usually this means that the function will fall well within the 20 line limit suggested, however it is not uncommon for a complex function which performs a very specific task (such as manipulating the contents of a particular input file, from a manufacturer, to fit the database schema)  to be 100 or more lines in length. Setting a hard and fast limit on the length of a region of code, be it an if block, a function/method, a class, etc. is not, in my opinion, conducive to maintainable code.

Another interesting item I saw noted on Planet Compsoc was this BBC article about Lenovo (who made my wonderful T60) preparing to sell laptops with Linux pre-installed on them. At the bottom of the article it says “Analysts believe that approximately 6% of computers users run Linux, similar to the numbers choosing Apple Macs”. I find this fact extreemly interesting as the company I previously worked for, in the holidays, had a statistics analyiser (which I installed) for their web logs, which showed approximately 6% of visitors to the site used Linux. The Mac quotient of Visitors was significantly less than that, however, and a full 90% of Visitors used Windows XP. Another random fact I found interesting was that use of IE 7 and IE 6 to visit the site was evenly split at 45% each. It makes me wonder how many of those have IE 7 simply because Windows Automatic Updates have installed it for them, and how many of the IE 6 users only have that because they never run the Automatic Updates.

Finally; At christmas I undetook the task of re-writing the stock management system I had previously written for my then employer. The re-write was necessary as the system had started out as a very small and simple thing, which had then had bits and pieces botched onto it as and when my boss decided that it would be nifty to have feature X (or Y or, more commonly, X, Y and Z. By lunchtime.). The result, as always with projects which develop like this, was a hideous mess with, for some reason, worked. Until it stopped working. And then something would hit the fan and land on my desk.

As a result I decided to dump the hacked-to-death php code, and re-write it using an MVC framework. I settled on Rails as it promised great productivity and allowing the developer to concentrate on writing functionality while it worried about the nittity-gritty, such as interfacing with the database. I completely re-wrote a system which had taken over 2 years to develop in 3 months, and Rails did deliver on its promises. Since I’ve stuck to the (somewhat enforced) MVC seperation of the Rails framework adding functionality is a doddle, as is maintaining the code. I have, however, found a small flaw in my approach.

The rails URL scheme opperates on the theme of ‘[controller]/[action]/[id]’, where the controller is the name of the controller (duh!), action is the method within that controller which is being called (and is also the name of the view) and id is an identifier (intended for identifing a db record, for example). I am aware this can be hacked somewhat with the Rails cofiguration, but deviating from the intended path for such frameworks often leads to problems down the line when the framework developers decide to fundamentally change the framework such that these hacks no longer work as intended. Anyway, back to the URL scheme. This is all fine and dandy when I have a stock management system with a ‘browse’ controller, which has such actions as ‘list’, ‘view’, ‘pdflist’ and so on, and an ‘edit’ controller which (also) has a ‘list’, ‘edit’, ‘uploadimages’, ‘uploadpdf’ etc. . (I know it looks like the two list actions violated the DRY (Don’t repeat yourself) philosophy, but they operate in fundamentally different ways, the browse one only operates on a specific subset of the database limited, among other things, to just what is in stock.)

My problem is that, although this is fine for a stock management system, I also need to integrate the old parts management system in as well (on the old system this was a HORRIFIC kludge). There are two obvious solutions, neither of which I’m keen on. One is to create a ‘parts’ controller in the existing app, which contains ‘editlist’, ‘viewlist’, ‘edit’, ‘view’, ‘uploadphotos’ etc. . This could possibly extended to move all of the stock stuff into a ‘stock’ controller. I do not like this as it a) feels too much like bolting the thing on, like the old mess which I’m obviously keen to avoid recreating, and b) the controllers would then get very large and the maintainability provided by seperating out these systems will vanish. The second alternative is to create a seperate rails app to do the parts management. As I mentioned I’m trying to integrate these systems, so creating a seperate app for it seems like a bad move towards that end. It would also mean hacking the Rails config to not assume it is at the root url, and setting up the webserver to rewrite urls. It is all hassle I’d like to avoid.

I’m now wondering if I should have use Django instead, where a project (or site) is supposed to be a collection of apps and I suspect that, as a result, the integrated stock and parts management system would be a lot easier to realise. I’m now back into the realm of trying to justify, either way, another rewrite of the system. I will add that Rails has given me some major performance headaches, and I’ve had to re-write portions of my code to not use the Rails helper functions, which I view as bad, as my code now relies of certain aspects of the Rails framerwork not changing, where as the helper functions should (I would hope) be updated to reflect changes made in the future, in order to achieve something of the order of an acceptable performance.

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