simevent

The simevent module provides the basic implementation for simulation events, or SimEvent in short. SimEvents are instances that store information about a method that can be called later by the simulator, as used in the event scheduling paradigm for discrete-event simulation. This later, or deferred, calling of a method is known as “deferred method invocation”.

The SimEventInterface in this module allows other implementations of the SimEvent, which will be recognized by the event lists and other classes.

class pydsol.core.simevent.SimEventInterface

Bases: ABC

SimEventInterface defines the properties that all SimEvent classes need to have. The most important property of a SimEvent is that it is executable, so it defines the execute() method.

abstract execute()

execute the event, usually as a method call on an object.

abstract property time: int | float

Return the absolute execution time, float or int.

abstract property priority: int

Return the priority; higher value is higher priority.

abstract property id: int

Return the unique id of of the SimEvent.

class pydsol.core.simevent.SimEvent(time: int | float, target, method: str, priority: int = 5, **kwargs)

Bases: SimEventInterface

SimEvent stores the information on a deferred method call that will be scheduled on the event list. Deferred method invocation is the execution of a method with arguments at a chosen time, rather than immediately.

The methods to implement are specified in the SimEventInterface.

Attributes:

• _absolute_time (float or int) – the absolute execution time of the SimEvent

• _priority (int) – the priority of the event when two events are scheduled at the same time; higher numbers indicate higher priority; typically, priorities are numbered 1 through 10 with a default priority of 5

• _id (int) – unique number of the event to act as a tie breaker when both the absolute time and the priority of the event are the same

• _target (object) – the object on which the method has to be called

• _method (method) – the method to call, stored as the attr of the target

• _kwargs (dict) – a dict with arguments to use for the method

__init__(time: int | float, target, method: str, priority: int = 5, **kwargs)

Parameters:

• time (float or int) – the absolute execution time of the SimEvent

• target (object) – the object instance on which the method has to be called

• method (str) – the name of the method to call, as a string

• priority (int (optional)) – the priority of the event when two events are scheduled at the same time. Higher numbers indicate higher priority. Typically, priorities are numbered 1 through 10 with a default priority of 5. When not provided, the default priority of 5 will be used.

• **kwargs (dict (optional)) – the arguments of the method call provided as comma-separated arg=value pairs

Raises:

DSOLError – when one of the arguments is not of the correct type, when: the method does not exist for the target, or when the method is not callable on the target.

execute()

Execute the stored method on the target object with the provided arguments for the method.

Returns:

This is quite important. Since the method will be called asynchronously, no object can do anything with a return value.

Return type:

None

Raises:

DSOLError – when the method call fails or returns an exception:

property time: float | int

Return the absolute execution time, float or int.

property priority: int

Return the priority; higher value is higher priority.

property id: int

Return the unique id of of the SimEvent.

property target: object

Return the target object instance to execute the method call on.

property method: str

Return the name of the method to be called on the target.

property kwargs: dict

Return the dict of arguments to be passed to the method.