How Do You Create a Module?

A module is a package of Pike code, typically a file. You can also write modules in C or C++, but how to do that is outside the scope of this tutorial.

The module is a file of Pike code. Lets say that we want to create a module called trig, which has two members: a method cos2 that calculates the square of the cosine function, and the constant pi.

We create a file, called trig.pmod, with the following contents:

float cos2(float f)
{
  return pow(cos(f), 2.0);
}

constant PI = 3.1415926535;

Now that the module file exists, we can use it. If we use it from a program that is stored in the same directory as trig.pmod, we can use the .module-name notation, so the program will look like this:

int main()
{
  write("The square of cos(pi/4) is " +
    .trig.cos2(.trig.PI/4) + ".\n");
  return 0;
}

Or, if we prefer to import the module:

import .trig; // Import the module from this directory

int main()
{
  write("The square of cos(pi/4) is " +
    cos2(PI/4) + ".\n");
  return 0;
}