const after initialization / pointers, references and values

[Vicente via Digitalmars-d]

First of all thanks for your replies, they are useful.

@Philippe:
A pure function is ok for initializing "default_nodes" but not 
for "nodes" because a pure function can't read a file.
The "static this" has the problem it needs know the initializer 
at compile time but I wanted to choose the initializer at run 
time.
I know "default_nodes" can be changed to immutable, but then it 
will require an explicit cast to remove the immutability.
The final class may be a good point, I'll try this one.

@Jakob:
Thank you, but I'll go with Philippe's suggestion.

@Wyatt:
Certainly ref parameters help a lot, but I'm trying to get a 
"Node" by returning (a reference to) it. Does the ref keyword 
apply to the return type?
Next time I'll post to D.learn, sorry for misplacing my question.

Regards,
   Vicente.