Smalltalk System

Smalltalk Architecture

Smalltalk System = OO Language + Class Library + Development Environment

Smalltalk System consists of the language, class libraries and development environment. In fact, Smalltalk Language itself is the smallest portion among them. It only defines variables, assigns the variables objects and sends objects messages. (We can't dare to say a language like this in comparison to C or Pascal)

Actually, the standard class library has the real core of Smalltalk language. The standard class library defines all kinds of information and behavior. This sophisticated library also contains lots of definitions. Furthermore, an user can define a class library by needs. Indeed, we can say Smalltalk programming as defining of this kind of class libraries. Surely, a development environment is required to define a class library.

Smalltalk Implementation

SmalltalkSystem.gif
Figure 1. Implementation of a Smalltalk System

Let me explain how a real Smalltalk system is implemented. A Smalltalk system is implemented by virtual image, virtual machine and hardware. In most of high level languages, a compiled image always is a set of codes for a specific hardware (machine codes), but, Smalltalk is using virtual machines for each hardware and this virtual machine can understand same binary image no matter what hardware is. A virtual machine is similar to interpreter of the Basic language. Therefore, we can run a virtual image of Smalltalk on anywhere as long as we had virtual machine on it.

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