class::Process
categories::Core>Kernel
summary:: Runtime environment for the virtual machine and interpreter.

description::
A Process is the runtime environment for the virtual machine and interpreter.
It has a subclass named link::Classes/Main:: which is where you should override the methods
of Process. There are two methods of interest. One is named code::startup:: and is
called after the class library has been compiled. The other is named code::run:: and
is called when the user chooses the Run menu command.

classMethods::

method::tailCallOptimize
Get or set tail call optimization. The default is on. Setting this to code::false:: can help with debugging by including intermediate levels in an error backtrace.

instanceMethods::

method::nowExecutingPath

Usage: code::thisProcess.nowExecutingPath::

Returns the full path to the file containing the code that is currently executing emphasis::interactively:: in the interpreter. Usually this is the current document. If the code block executes another file on disk, using link::Classes/String#-load:: or link::Classes/String#-loadPaths::, teletype::nowExecutingPath:: will be the location of the executed file.

teletype::nowExecutingPath:: is valid only for interactive code, i.e., code files with a teletype::.scd:: extension. It does not apply to class definitions (teletype::.sc::). For that, use code::thisMethod.filenameSymbol:: or code::this.class.filenameSymbol::.

This method is supported in the SuperCollider IDE, the macOS-only SuperCollider.app, and the scel (SuperCollider-Emacs-Lisp) environment. In other editor environments, it will return code::nil::.

WARNING:: teletype::nowExecutingPath:: has a corresponding setter method, teletype::nowExecutingPath_::, for internal use only by the interpreter. Do not call the setter method!::

method::startup

called after the class library has been compiled. Override this in class link::Classes/Main:: to do whatever you want.

method::run

called when the user chooses the Run menu command. Override this in class link::Classes/Main:: to do whatever you want.

method::mainThread

The top-level link::Classes/Thread::, i.e the link::Classes/Thread#-parent#parent:: of all
other Threads. This instance of Thread always exists and is created with the Process when
SuperCollider starts.

discussion::

All SuperCollider code initially runs in the context of the main Thread:

list::
## Code evaluated in code editor
## Code evaluated on command line
## Tasks scheduled on any link::Classes/Clock::
## Functions evaluated in response to incoming OSC and MIDI messages
::

This means that link::Classes/Thread#.thisThread#thisThread:: will always initially point
to the main Thread. However, when some code starts a link::Classes/Routine::, the Routine
becomes the current Thread, with the main Thread as its parent.
