[Seaside] [OT] Why use an image file ? (was Re: Seaside & Ruby Rails Compared)

[radoslav hodnicak]

On Wed, 7 Sep 2005 seaside at fbeausoleil.ftml.net wrote:

> Hi !
>
> radoslav hodnicak said the following on 2005-09-06 19:40:
>
>> Loading postgres client 0.9.2 into clean image and then glorp 0.3.138 
> *should* work, I tested it.
>
>
> You see, that's what I never liked about working with images.  Maybe I'm just 
> old school, but if I have two or three projects going on in my image, should 
> I just delete my work just to get some other part working ?

...

that's not what I'm saying. Loading into clean image is just the process 
of eliminating other factors that might lead to failure. If it doesn't 
work after loading into clean image, then it's a problem for me (I'm the 
glorp port maintainer). You don't need to delete your work to get other 
parts working, although sometime you might have conflicting changes when 
it comes to system classes.


> Please, I don't want to offend anyone !  I understand the concept behind the 
> image, and I *really* want to like Smalltalk, but the image thing has stopped 
> me every time.  What I probably need are references as to *why* it is 
> considered better to use an image instead of plain old files.

This question comes up every so often, and indeed images are strange 
concept to many people who look at smalltalk for the first time. However, 
you just have to realize that no matter what programming laguage you use, 
at some point you end up with parts of memory where your data and code 
resides.

Consider writing program in C. You write it, compile it, link it and end 
up with binary file that is then loaded into memory by operating system. 
It is sort-of like smalltalk image, with the difference that it's one way 
- from disk to memory.

In smalltalk, interactivity and direct access to everything is the "prime 
directive". That's why you can change the memory image with normal tools 
(this includes loading or creating new code), that's why you can inspect 
and view everything in it, that's why you can save it back to disk and 
restore later.

I suspect one could always build a new image from files and throw it away 
at exit. But I think it would lead to similar "object blindness" 
java/c++/... programmers develop, because for them objects are just some 
lines in header files. They never had their objects under microscope in 
inspectors, telling them what to do, watching them change and yelling at 
them when something didn't work out as planned :-)

rado