Environments

An Environments is a collection of things that can be accessed by name. When we start the SuperCollider IDE, it automatically creates an environment that can be evaluated by the following line:

currentEnvironment;

If this is your first evaluated command, the environment should be empty. This environment contains variables, more specifically all environment variables. A variable starting with a tilde is a environment variable, e.g.:

~number = 100;

If we re-evaluate the first statement, we can observe that currentEnvironment contains the value 100 and this value can be accessed via the name number. In fact ~number is a shortcut for

currentEnvironment.at(\number);

and an assignment like ~number = 100; stands for

currentEnvironment.put(\number, 100);

We can create a fresh environment and push it onto the stack of environments. In fact, that is more or less what happens when we call a function.

Let us create an environment by using a global variable d. Then we push it onto the stack. Additional, let us create a new environment variable for the environment d.

d = ()
d.push;
~number = 233;

If we re-evaluate

currentEnvironment

we can see the new variable. Note that even the names of these two variables are the same, they live in different environments. If we call

d.pop;

we remove d from the stack and currentEnvironment is equal to the environment before we pushed d onto the stack. ~number is now equals 100.