Polymorphism, when done right, is a powerful method of simplifying software implementation. There are multiple types of polymorphism, here is a simple example of runtime (aka dynamic) polymorphism in C:

#include <stdio.h>
#include <stdlib.h>

typedef struct animal_s {
    void (*speak)(void);
} animal_t;

void speak_like_a_duck(void)
{
    printf("quack!\r\n");
}

void speak_like_a_dog(void)
{
    printf("woof!\r\n");
}

animal_t *create_duck(void)
{
    animal_t *duck = malloc(sizeof(animal_t));
    duck->speak = &speak_like_a_duck;
    return(duck);
}

animal_t *create_dog(void)
{
    animal_t *dog …

Moving averages are useful since they do not require a buffer of samples to be maintained. Here is a simple implementation in C:

#include <stdio.h>

float ave(float num)
{
    static float fAve = 0.0f;
    static unsigned int fSmp = 0;
    float weight = 0.0f;

    fSmp++;
    weight = 1.0f / fSmp;
    fAve = (weight * num) + ((1 - weight) * fAve);

    return(fAve);
}

int main(int argc, const char *argv[])
{
    char str[100] = {0};
    float num = 0;

    /* Run until user enters …

Need to calculate a geometric mean in Python? You could use Numpy or this one-liner:

# NOTE: This import is only needed for Python3.
from functools import reduce

# Geometric mean of list `n`:
geomean = lambda n: reduce(lambda x,y: x*y, n) ** (1.0 / len(n))

print(geomean([1,2,3,4]))
# Result: 2.2133638394

Here is a neat little control sandbox put together using PhysicsJS and JSFiddle. Try implementing your own stepController() to see if you can balance the circle above the square.

Python does not allow string to be modified via indexed assignment. For example, a = "hello"; a[1] = "x" will produce a TypeError: 'str' object does not support item assignment error. Grr!

The following one-liner stridxrep() can be used if the need ever arises:

a = "hello"

# Python doesn't allow the following:
# a[1] = "x"

# A 'string index replace' function.
stridxrep = lambda s, i, r: "".join([(s[x] if x != i else r) for x in …

Technology moves fast. Really fast. The following are some software technologies that I will be keeping an eye on in 2014:

1. Docker - Brilliant container manager.
2. Rust - Promising systems language.
3. Emscripten - Mind-bending JavaScript compiler.
4. D3.js - Beautiful data visualization.

While these technologies are not necessarily new, my prior experience with them is limited.

NOTE: An update to this post is available here.

Task lists are great! Need to do something eventually but don't have the time or motivation to do it now? Add it to a task list (think of it as procrastination management)!

When managing task lists on a computer, I prefer a file-based plain-text approach. As a software developer and avid Vim user, I have found this method to be the most flexible, reliable, and easy …

When picking a simple but useful data format, CSV is tough to beat. However, looking through large files can be cumbersome. For this reason, I threw together CsvPal, a simple command-line utility for filtering out columns of interest. Check it out if you frequently work with large CSV files.