Thursday, 3 April 2014

Code Line Numbers

I had a programmer sat with me the other day, he seems a good one too, though I've not seen his actual code.  And he surprised me by peering at my development environment and saying...

"How can you program without line numbers on?"

He was serious, we were exchanging information to ensure I wrote code to meet his coding standards... So why not program with line numbers... Well, I could be annoying and say, I don't write BASIC, so I don't need line numbers... I also don't count K-Locs as a form of reward as to how busy I've been, nor use it as a measure of how productive I am... So really I have to ask myself the opposite, "Why don't you program with line numbers on Xel?"

And the simple answer for me is experience.  Maybe you're different, and you like line numbers, if so "This is not the article you are looking for, move along... Move along"... But to answer for myself, it is simply because I'm human, and the human mind likes to see patterns, it likes to see things and tries it's hardest to impose some semblance of meaning into them.  And for me, if I turn line numbers on then I expect 5 to follow 4, and 4 to have followed 3, and 2 to have come before 3 but after 1... It's an order, and in modern code it is an incorrect order because we should be writing, if not object orientated, then at least functional code.

Functions can be called in any order, objects can be instantiated and used differently by different users, your code itself might do one sequence one way today but a different sequence tomorrow.  The functions themselves still do the same single job with the same input, as per their definition, but code as a whole is no longer linear.

So over time my personal experience has told me to group my code into a simple, but not formal - until this blog post - order, which is "Constructors at the top", then the functions defined "in order of frequency of use", so if you have an update function called all the time in a class, put it at the top, so its easy to spot after your constructors.  Especially in a language like C++ where your constructors can be very brief - or should be very brief, if they're not go rear Scott Meters & Bjarne Stroustrop on the topic!

And then functions are laid out in order of use, least used or single call functions are at the bottom.  I've just come to this pattern, its quite hard to even define it here in words, I suppose I should give code examples, but I'll leave this for another day and come full circle to answer the question "How can you program without line numbers on?"

"Code/Function use is not linear, don't give any indicates to your mind that it is, and if you're going to argue about the contents of one function, your function is too long, break it down into sub-functions which will fit onto the screen as a whole and so you don't need line numbers you can see the whole function in a single pass of the eye".

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