Smalltalk and Object Orientation: an Introduction - Free

solutions are needed which suit the require ments of less technically complex systems, such as a
database server which is accessed by a small number of interacting Smalltalk clients.
Improved support for deploying applications is required. The process of removing as many system
classes as possible without damaging the application’s operation is still largely an art rather than a
science. VisualWorks 2.5 does give greater support for this, however it is still severely limited in its
operation.
Finally, there needs to be a convergence between the di fferent Smalltalk dialects. This will happen
to some extent through the new ANSI standard. However, if this standard does not cover issues such as
the user interface, database access, web access, the use of dynamically linked libraries and OLE, then it
will have only limited success.
33.3 Object oriented development toolkits
For Smalltalk to maintain its position as a mainstream language it must be supported by appropriate
development tools, as well as by a number of language vendors. The merger of Digitalk and Parcplace
systems raised the prospect of the emergence of essentially a single language vendor (as ParcPlace and
Digitalk between them accounted for the majority of Smalltalk system sales). This has been an
impediment to a language’s success in the past. F or example, developers are unwilling to commit to a
language which, on the demise of their system supplier, forces them to re -implement the whole system
in a new language. However IBM have entered the market with their range of Smalltalk products thus
alleviating the situation to a certain extent.
However we are still left with the issue of the range of development tools and toolkits available. It is
possible to classify object oriented development toolkits into a number of categories:
• Object oriented lang uage compilers and linkers . These tend to be command line programs
which read in a source code file and produce object files which are then combined with other
object files to create a stand alone executable. They are typically used in an Edit -Compile-Link-
Execute cycle in which the various tools used are poorly integrated (if they are integrated at all).
• Object oriented application development environments . Object oriented Application
Development Environments (or OOADEs) are comprehensive development environments that
not only possess highly integrated development tools but also provide a far greater level of
developer support than the basic language compilers. For example, database access, use r
interface construction, code generation and libraries of reusable components. Typically
OOADEs exploit an iterative development cycle in which the developer writes some code,
compiles it in-situ and executes it before writing some more code.
• Object oriented CASE (OOD methodology -based) tools. OO CASE tools differ from the OO
ADEs because they support one or more OOD methodologies. The most common OOD
methodologies used with OO CASE tools are OMT and Booch. These two accounted for over
50% of OOD methodologies used world wide in 1995. Given this, it is likely that the Unified
Modeling Language (UML) will have a significant impact in the future, as it is the inheritor of
both OMT and Booch.
There are in fact two different types of OO CASE to ols available: OO analysis and design
tools and OO Integrated CASE tools. The former act as diagramming tools while the latter are
model-based code generating tools. Most of the code generation tools support C++ although
versions for Smalltalk have been ap pearing since the end of 1995. This is now a significant
market which increased in the US by 82% in 1995 to be worth about $138 million.
Smalltalk examples of each of these can be identified. For example gnu -Smalltalk falls into the first
category, while VisualWorks itself falls into the second. There are also a growing number of Smalltalk
based OO CASE tools. For example, Rational (probably the most influential OO CASE developer
having Grady Booch, Jim Rumbaugh and Ivar Jacobson working for them) has a ve rsion of its product
ROSE for Smalltalk (It also produces versions of Rational ROSE for C++, SQL Windows and Ada).
However it is worth noting that although OO CASE tools are the fastest growing product area, this is
an area in which Smalltalk has been a re latively late entrant. OO CASE tools first started appearing
commercially , in any number, around 1992. It was three years before many of these tools offered direct
280