Architecture details
Click on the picture to get details about Gambas architecture...
A drawing is better than a long speech. And I'm fond of this kind
of diagram that make people think that program design is completely
clean and careful thought ;-).
The
Development Environment hides this machinery behind a pretty graphical interface.
Project
A project is a set of files stored in one
directory.
A project can contain source files (forms, classes, modules)
or any data files of any types:
-
The project configuration is stored in a file named
".project".
-
The source files are stored in a sub-directory named
".src".
-
Data files are stored in the project directory or in visible sub-directories.
Archiver
The
Archiver is a program named
gba3.
It transforms your project, the compiled files included, in one sole
executable file.
Compiler
The
Compiler is a program named
gbc3.
It transforms your project's forms, classes and modules files into binary
compiled files that can be understood and executed by the interpreter.
Executable Files
A Gambas executable file is an uncompressed archive of your project, the compiled files included.
The archive file is marked as a script with the
#!/usr/bin/gbx3
magic header, so that Linux executes it by calling the interpreter transparently.
Compiled Files
A compiled file is a binary representation of
a class, that contains every information useful to the interpreter :
functions transformed to byte code, constants, variables definitions,
debugging information, etc.
Using mmap System Call
If your project was compiled as an executable, i.e. as an archive,
the interpreter maps the file into memory instead of loading it. It is worth doing !
Interpreter
The
Interpreter is a program named
gbx3.
It executes the byte code of the compiled file generated
by the compiler.
Class Loader
The
Class Loader loads compiled forms, classes and modules into the interpreter.
Execution Unit
The
Execution Unit is the heart of the interpreter.
It dispatches and executes each byte-code instruction
generated by the compiler.
Debugger
The
Debugger is a command-line tool embedded in the interpreter.
It allows the development environment to debug a Gambas program by running it step by step,
watching the stack contents, evaluating any expression in the current running context...
Subroutines
The
Subroutines are the interpreter
functions associated to the corresponding Gambas
functions like
Sin,
Left,
Stat, etc. or
operators like
+,
-,
*,
&, etc.
Component Interface
The
Component Interface is a set of
routines and services used by the components to communicate with the
interpreter.
The interpreter's internals are hidden that way.
Component Loader
The
Component Loader is the part of the
interpreter that loads components shared libraries, gives them access to the
Component Interface, and that publishes their interface to the other
components.
Native classes
The
Native Classes are classes that can be used without loading
any component.
They are integrated in the interpreter, and can be looked
upon as a part of the Gambas language.
Components
Components are shared libraries that are loaded at run time by the interpreter.
They can contain new classes and hook routines such as event loop management, shell arguments
analyze, etc. They can publish a set of routines as an interface to other components also.
Components can be written in Gambas too. The archiver generates them as Gambas executables
from Gambas projects marked as "component projects".