Athena Developer Guide

Athena
Chapter 14 Tools and ToolSvc Version/Issue: 2.0.0
Chapter 14
Tools and ToolSvc
14.1 Overview
Tools are light weight objects whose purpose is to help other components perform their work. A
framework service, the ToolSvc, is responsible for creating and managing Tools. An Algorithm
requests the tools it needs to the ToolSvc, specifying if requesting a private instance by declaring
itself as the parent. Since Tools are managed by the ToolSvc, any component 1 can request a tool.
Only Algorithms and Services can declare themselves as Tools parents.
In this chapter we first describe these objects and the difference between “private” and “shared” tools.
We then look at the AlgTool base class and show how to write concrete Tools.
In section 14.3 we describe the ToolSvc and show how a component can retrieve Tools via the
service.
Finally we describe Associators, common utility GaudiTools for which we provide the interface and
base class.
14.2 Tools and Services
As mentioned elsewhere Algorithms make use of framework services to perform their work. In general
the same instance of a service is used by many algorithms and Services are setup and initialized once at
the beginning of the job by the framework. Algorithms also delegate some of their work to
sub-algorithms. Creation and execution of sub-algorithms are the responsibilities of the parent
1. In this chapter we will use an Algorithm as example component requesting tools.
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