[Tutor] A couple of somewhat esoteric questions

[Dave Angel]

"Clayton Kirkwood" <crk at godblessthe.us> Wrote in message:
> 
> 
> !-----Original Message-----
> !From: Tutor [mailto:tutor-bounces+crk=godblessthe.us at python.org] On
> !Behalf Of Steven D'Aprano
...
> 
> For clarification, a key only has one value which can be changed. 

No, because the key has to be immutable, like a string or an int.

> Multiple
> keys can have the same value (hopefully not to the same memory location,
> because one would usually not want the change of one key's value to alter
> another key's value. As to the hash table, yes, I agree that this would be
> one to many, hence the chains.

Memory locations are an implementation detail. We're talking in
 this paragraph about keys and values. A value is an object, the
 dict provides a one-way mapping from immutable key to an
 arbitrary value object. If the value objects happen to be
 immutable,  it makes no difference if a program uses the same
 value for multiple keys. If the values are not immutable,  python
 makes no assurance whether two values are equal, or identical. If
 the latter is undesirable for a particular use, it's up to the
 application logic to prevent it. It's probably more often useful
 than problematic. Python makes no such assurances.
 




> !Can you give a concrete example of what you're trying to do?
> 
> The changing of the order is necessary when you want numeric indexing, say
> for columns or rows.
> 

No idea how this relates to dicts, which have no order, nor rows
 nor columns. Make it concrete.


-- 
DaveA