What tracers are made of

In object-oriented languages like SMALLTALK-80, browsers and irtpeciors are used to provide insight into the static worlc! of objects and their relations, debuggers are used to inspect and modify states of computation. This article presents a detailed description of TRICK, a basic toolkit to build iracers. Tracers can be used to uncover the dynamic properties of SMALLTALK-$0 programs. As an example of how the power of this kit may be used by an experienced programmer, we describe the TUCK system, a visual trace construction kit, by means of which trace specifications may be set up through direct manipulation of graphical objects. 1 Tracers' TRICK In object-oriented languages like SMALLTALK-80, browsers and inpectors are used to provide insight into the static world of objects and their relations, debuggers are used to ins;?ect and modify states of computation (cf. [4]). We suggest to build tracers that can be used to uncover the dynamic properties of programs. Like browsers and inspectors, tracers live in windows, an arbitrary number of which can coexist concurrently and may cooperate with each other as well as with their cousins: the brcwsers, inspectors, and debuggers. Also, they are manipulated in similar ways, may be accessed from the other tools, and in turn provide access to these tools. Permission to copv without fee all or part of this material is granted provided that the copies are not made or distributed for direct commercial advantage, the ACM copyright notice and the title of the publication and its date appear, and notice is given that copying is by permission of the Association for Computing Machinery. To copy otherwise, or to republish, requires a fee and/or specific permission. This paper describes TRICK (tracers' internal construction kit), the low level program interface for the SMALLTALK-programmer who wants to build textual or graphical tracers. We will show how it has been successfully used to build TRACK (trace construction kit), which is described in more detail in [2]. Browsers and inspectors obviously can be used to look at the code that implements them. Figure 1 depicts an analogous situation in which the TRACK tracer is applied to some of the components it is built of; the trace shows how a message to be traced is passed through the various subfilters of a truce filter which is one of the buildings blocks available within TRICK. 2 Tracing Object-Oriented Programs Standard tracing tools in object-oriented languages (like …