Table of Contents |
The System Library > Miscellaneous
Library Definitions
Miscellaneous Library Definitions
This section describes a few miscellaneous functions and classes that the system library defines.
Functions
forEachInstance(*cls*, *func*)
This function is a simple object “iterator” function; it iterates (in arbitrary order) over all instances of the class given by the cls argument, and for each instance invokes the function given by func, passing the current instance as the function’s single argument.
This function is a convenience. You can use it as an alternative to
writing a loop involving the firstObj/nextObj functions. For example, to
set the isAnimate property for all instances
of Actor:
forEachInstance(Actor, {obj: obj.isAnimate = true});
\_default_display_fn(*val*)
This function simply calls the function
tadsSay(val) from the tads-io
intrinsic function set. It’s defined as a function here simply so that
the library can register it with the VM as the default display function.
Classes
class Exception: object
This class is defined to serve as the base class for all exceptions,
including run-time errors and program-defined exceptions. The class
defines a method, displayException(), that
should be overridden in all subclasses to display an appropriate message
describing the exception.
class RuntimeError: Exception
This class is the base class for all run-time exceptions that the VM itself throws.
class ModuleExecObject: object
This is the base class for PreinitObject and InitObject. (See the section on initialization for full details on these objects.)
mainGlobal: object
This object simply serves as a repository for global variables for the
system library. In particular, this object’s property
preinited\_ stores the pre-initialization
status; this property is set to true after
pre-initialization has been completed, so that the library knows that
the process won’t have to be repeated when the program is started.
TADS 3 System Manual
Table of Contents |
The System Library > Miscellaneous
Library Definitions