Contexts

Contexts are a solution to the problem of requiring global state.

There are multiple nested levels of context in score :

• score::ApplicationContext : where classes are registered
• score::GUIApplicationContext : extends ApplicationContext, available in the GUI software (not in the command-line & embedded players)
• score::DocumentContext
• Process::Context
• Various execution contexts, for audio, etc.

A context is simply a class that references other classes useful in a given context.

For instance, score::ApplicationContext gives access to the factories, etc. score::DocumentContext gives access to the command and selection stack of a given document, as well as the model object tree.

Ideally, contexts should not be called through functions but passed from parent to child, to respect dependency injection and minimize the number of global function calls.

Some common classes will have a built-in reference to the ApplicationContext : for instance all commands, and all serialization classes