Saturday, 24 December 2016

Travelling to London by train

I currently work for a very small software company, which is big change for me as this company has 3 orders of magnitude fewer employees than any other company I've worked for before. There are many changes for me, but the one I want to talk about today is how I approach expenses.

In previous jobs, I didn't care about expenses, if the company wanted me to go somewhere I would expect the company to pay the full cost, even if it meant silly money for a train ticket due to being asked to be in London next morning, but in my current job I almost feel that I'm paying for it personally, which means, among other things, that I try to minimize travel or look for cheaper alternatives.

A few weeks ago I had to go from Sheffield to London (~ 170 miles) to see a client for an urgent meeting in the morning with just two days notice, so I had several alternatives:

Means of Travel Cost To Company
Car to Customer site £105
Car To North London, then Tube £100
Train, then Tube £186

Had the meeting been around 13:00 I would've been able to catch an off-peak train so this is what the costs would be:

Means of Travel Cost To Company
Car to Customer site £105
Car To North London, then Tube £100
Train, then Tube £80

It is clear that the train companies use price sensitivity to the full, particularly when it comes to travel to London, but there is a way to fight back and that is to buy the train ticket in tranches, which is what I did:

Means of Travel Cost To Company
Sheffield To Leicester £34
Leicester To Market Harbourough £11.6
Market Harbourough to Luton £27
Luton to London St Pancras £27.5
Tube £5.6

Including booking fee, the grand total was £107, which is slightly more than drive but has two major advantages:
  • Arrival Time is significantly less dependent on external factors (namely traffic)
  • I can work on the train.
It's only fair to point out that some of these are day returns so it wouldn't work for all instances and also that booking tickets in advance can result in pretty reasonable prices too.

I made a point about travel to London, I think other cities like Leeds, Manchester and Birmingham also have peak time fares but the premium is not anywhere near as much as to London.

Finally, it would probably be trivial to optimize the cost of the tickets by using the available API or even national rail's website itself, given it's query friendly url format, not tried it though

Saturday, 10 December 2016

Different Approaches to problem solving - Typescript Regular Expression escaping.

One our developers left the company last week and one of the last things he did was to expand the password reset functionality so that managers can change the passwords of their direct reports on the system (most of our users don't have emails and we've not got SMS messaging working yet)

In any case, the password complexity rules are as follows:
  • The password length must be greater than or equal to 8
  • The password must contain one or more uppercase characters
  • The password must contain one or more lowercase characters
  • The password must contain one or more numeric values
This is the regex used client side to validate these rules.


This is the actual regular expression that the browser was seeing after transpiling:


There are no typos, the second group is missing the backward slash before the d,  while the third group has kept the backslash before the n, I don't understand why this is, but we can ignore this for the purposes of this little tale.

In any case, the intention was this:

The actual expression was this:

This would not have been an issue had it been tested properly or had our convention for development passwords deviated from variations on leet speak versions of the word password, which contained the required d.


So the new guy joins us and he has this issue assigned to him. He clearly struggles to understand the issue, although I make it clear to him that if he gets stuck he should not hesitate to talk to me, but he doesn't. In fact, in the first two days he only asks me about a single issue, which turns out to be a node issue and was actually preventing him from getting started.

In any case, at the end of his second day of work, he submits a pull request and goes offline. I look at the pull request and this is what he came up with:


This is exactly what is required and is far simpler than the original regular expression, while at the same time bypassing any potential escaping issues.

I'll state the obvious, which is:
Sometimes a head on approach is less likely to solve an issue than a side ways approach

If you know why the escaping issue (We're using Aurelia) leave a comment.