2/18/02
- AutoCAD and the dblist command
- The presence of a database in AutoCAD allows the user to
access previous commands.
- The user also has the possibility to tell AutoCAD how many
previous lines of commands to display.
- By viewing the database list, one begins to gain some
insight to how the program works.
- Since the commands are text based (as demonstrated in the
database list) one realizes that AutoCAD is a command language program.
- Even though the user may be using a graphic interface, it is
still text based.
- This type of computer / user relationship is called a GUI;
(graphic user interface).
- Here the user sees icons and uses the mouse to instruct the
computer. What this does is allow the user to command what the core of the program does.
- Advantages of the command language program.
- Since the data is created and stored in a text format, ASCII
can be used.
- This allows the user to theoretically create text files that
contain lines of commands that can be ran in AutoCAD. (Assuming the file is executable.
- This is called a command file, script file, or macro.
- The programming language used to do this is called lisp:
(list processing).
- Another way of viewing information in AutoCAD is by using
the list command.
- This is a way one can view detailed commands and information
associated with an object.
- One of the categories viewable under the list is the objects
handle.
- This is AutoCAD’s I.D. tag system.
- All handles must be unique.
- It is important to remember that the AutoCAD and Computer
vocabularies are often different. For example:
- An AutoCAD line is thought of as having a measurable length,
where as, with the generic computer vocabulary, a line is defined by two points, extending
infinitely in either direction.
- An AutoCAD polygon is defined as having sides of equal
lengths, with equal angles between each segment, where in the more generic computer
vocabulary, the sides of polygons can be of any length.
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