TITLE: Another Advertisement for Smalltalk
AUTHOR: Eugene Wallingford
DATE: June 10, 2005 3:10 PM
DESC: Why don't I program in Smalltalk more often?
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BODY:
Last week, I posted a note on a cool consequence
of Smalltalk being written in Smalltalk, the
ability to change the compiler
to handle new kinds of numeric literals. Here
is another neat little feature of Smalltalk:
You can quit the interpreter in the middle
of executing code, and when you start back up the
interpreter will finish executing the code!
Consider this snippet of code:
Smalltalk snapshot: true andQuit: true.
... code to execute at next start-up, such as:
PWS serveOnPort: 80 loggingTo: 'log.txt'
If you execute this piece of code, whether as a
method body or as stand-alone code in a workspace,
it will execute the first statement -- which
saves the image and quits. But in saving the
image, you save the state of the execution, which
is precisely this point in the code being executed.
When you next start up the system, it will resume
write where it left off, in this case with the
message to start up a web server.
How I wish my Java environments did this...
This is another one of those things that you want
Java, Perl, Python, and Ruby programmers to know
about Smalltalk: it isn't just a language; it is
a living system of objects. When you program in
Smalltalk, you don't think of building a new program
from scratch; you think of molding and growing the
initial system to meet your needs.
This example is from
Squeak,
the open-source Smalltalk I use when I have the
chance to use Smalltalk. I ran across the idea
at
Blaine Buxton's blog,
and he found the idea in a Squeak Swiki entry for
running a Squeak image headless.
(A "headless image" is one that doesn't come up
interactively with a user. That is especially
useful for running the system in the background
to drive some application, say a web server.)
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