meganursula: (cthullu)
[personal profile] meganursula
Question for object oriented gurus:

I am currently reviewing some code implementing a current standard of an algorithm i frequently use. (I want to examine some modifications to the algorithm, but, i need a good baseline to compare to.) In it we see something like:

struct velocity
{
int size;
double v[D_max]
};


There are a lot of these structs - position, quantum, etc.

Thing is, in my code, i generally declare
num_dim = n; // this is what they are using size for up above
double position[num_dim];
double velocity[num_dim];


(quantum, for the record, appears to be taking the place of what i usually declare as a constant Eps, and is used to get around numerical issues when looking for zero.)

etc. I do not have additional structs. Thing is, i find all this structifying to be sort of pointless and irritating. Pointless because i do not know what the structs are adding to the code. Irritating because i think they add a level of obfuscation, rendering the code not only longer, but also much less readable.

My question - what, if anything, am i missing in this situation? I get, generally, what object oriented-ness does for you. But i haven't used it very much in the past 6 or so years. (Matlab's excuse for object oriented isn't worth bothering with.) Right now i find myself faced with a few examples of modern code that are object oriented up the ass, and it just seems like it all has been taken too far. If i give myself three months will i become a believer? Will i stop feeling like there should be some sort of natural progression through code and adapt to having objects interacting at will?

Date: 2008-09-12 02:56 pm (UTC)
From: [identity profile] bhudson.livejournal.com
So, port your matlab to C, how much code is that?

Date: 2008-09-12 04:43 pm (UTC)
From: [identity profile] mh75.livejournal.com
My code - *maybe* two pages.

Date: 2008-09-12 05:18 pm (UTC)
From: [identity profile] bhudson.livejournal.com
You write really verbose matlab if you could port it to C in just 6 times as many lines. One project I was on, we told the team in charge of the ROM how many SLOC we had, they multiplied by 18 bytes/SLOC and told us that's how much ROM we could use. We begged for 10x as much because we were using C++, not C as they had assumed, and thus we could express a lot more machine instructions in one line of code. Then, I got tasked with getting the code down to just 180 bytes per line -- eventually we got there.

One thing I should probably have thought of, but wasn't thinking it since I don't usually write this kind of code: if you're basically trolling through dense matrices and vectors, then, yeah, making lots of structures is pretty silly (except for error handling, but your competition isn't doing that, which makes me weep). It matters a lot more when you have complex data structures all linked together by pointers -- which is what I usually deal with. And once I've gone down that bridge, somewhere I probably needed a vector, and so I want your dense linear algebra function to be able to take that vector type instead of forcing me to copy it into an array.

Date: 2008-09-12 05:24 pm (UTC)
From: [identity profile] mh75.livejournal.com
You write really verbose matlab if you could port it to C in just 6 times as many lines.

No, i don't think so. I think you're overestimating the complexity of the actual algorithm.

I suppose all these numbers are fuzzy, though, so maybe before i make people think i'm being too precise i'd have to go through the exercise and actually count the code lines (as opposed to comment lines).

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Megan Hazen

May 2020

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