[erlang-questions] Stuff that breaks when you move it

[Bengt Kleberg]

Greetings,

One solution is Plan9 (http://plan9.bell-labs.com/plan9/).


bengt

On Mon, 2009-08-03 at 15:04 +0200, Joe Armstrong wrote:
> There's two kinds of stuff:
> 
>     A) Stuff which doesn't break when you move it
>     B) Stuff which breaks when you move it
> 
> Type A includes:
>     zip files,  PDF files, jpg files, mp3 files, ...
> 
> 
> Type B includes:
>      Erlang, HTML files, DRM protected files, erlang beam files, ...
> 
> 
> A good general principle is:
> 
>     P-1 - "Stuff should not break if you move it to a new directory"
> 
> A is good B is bad.
> 
> Experiment:
> 
>     # cd /usr/local/lib
>     # mv erlang globble
>     # globble/bin/erl
>     exec: 28: /usr/local/lib/erlang/erts-5.7.1/bin/erlexec: not found
> 
> Thus Erlang is in B.
> 
> But it doesn't have to be so - this is a bug not a feature
> 
> Note: 1) This problem (stuff breaking when you move it) is
> a particular pain when you have to make something work
> that depends upon several different components and each one
> individually breaks when you move it.
> 
> 2) Sometimes stuff cannot be moved to where the author wanted
> you to move it to. So if you have not got admin rights
> you *cannot* move your program to /bin (or whatever)
> 
> So lets add:
> 
>      P-2: It should be possible to move stuff to *any*
>           directory in the file system to which you have write access
>           without breaking it.
> 
> And while we're on the subject:
> 
>      P-3: We should be able to *remove* stuff without breaking
>      other stuff that is not dependent upon the stuff we have removed.
> 
>  And
> 
>      P-4: If we add stuff to the system and then remove it we should put
>      the system back to the state it was in before we added the
>      stuff that we removed. (Possibly we might change the state of the
>      system log to say that we have added and removed something,
>      but nothing else should happen)
> 
> Very little software obeys principles P-1 to P-4.
> 
> This is bad.
> 
> Fix it.
> 
> Cheers
> 
> /Joe
> 
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