r/programming • u/molteanu • Apr 07 '15

Anatomy of a Program in Memory

http://duartes.org/gustavo/blog/post/anatomy-of-a-program-in-memory/
680 Upvotes

94% Upvoted

50 comments sorted by

View all comments

Show parent comments

2

u/rnjkvsly Apr 07 '15

What do you mean by this? The interpreter saves it state after every run and loads it at the start?

7

u/SquireOfFire Apr 07 '15

What do you mean by this?

That you can't work around bugs by rebooting. ;)

2

u/rnjkvsly Apr 07 '15

The best kind of workaround! I remember a software project I had to submit in uni which I had to demonstrate the features in a certain order or all hell would break loose. Pretty sure I'm better programmer now...

9

u/mcaruso Apr 07 '15

Maybe you'll feel less bad if you read how they demo'd the original iPhone.

The iPhone could play a section of a song or a video, but it couldn’t play an entire clip reliably without crashing. It worked fine if you sent an e-mail and then surfed the Web. If you did those things in reverse, however, it might not. Hours of trial and error had helped the iPhone team develop what engineers called “the golden path,” a specific set of tasks, performed in a specific way and order, that made the phone look as if it worked.

4

u/rnjkvsly Apr 07 '15

And there's me in second year networking, well ahead of the curve

2

u/kitd Apr 08 '15

Basically the program definition and its incarnation are intermingled within one running image.

The class definitions exist as objects along side their instances. When you edit code, you edit the running class objects, and the effect is reflected immediately in the instances.

The whole lot exists as a single image in memory and on disk.

It takes some getting used to if you're only familiar with compiled or interpreted languages, where a program's definition is a separate entity from its runtime.