[Oberon] Module aliases - what is the correct way to handle them

[Joerg]

thinking of it, the importscope idea is like a generalization of SYSTEM.
Currently, ORB has a special invisible scope for the module SYSTEM. And it has a special treatment like IF modid1 = “SYSTEM“ THEN it links those objects to topscope.

Currently you can compile

IMPORT S1 := SYSTEM, S2 := SYSTEM;

this is because SYSTEM lives in an own scope with name „system“.

The generalization of it would be that all imported modules (including SYSTEM) are imported into importscope and the special treatment IF modid1=“SYSTEM“ is replaced with a search in importscope.

Let me see, how I find time to implement this idea...

br
Jörg

> Am 16.02.2020 um 13:37 schrieb Joerg <joerg.straube at iaeth.ch>:
> 
> Chris
> 
> you‘re absolutely right the aliases must not be allowed on the righthand side.
> 
> If I think of a possible implementation, the righthand sides and lefthand sides might live in different scopes, eg lefthand side are objects visible in the well known topscope, the righthand sides (aka filenames :-) might live in a new importscope... Just thinking loud.
> 
> br
> Jörg
> 
>> Am 16.02.2020 um 13:16 schrieb Chris Burrows <chris at cfbsoftware.com>:
>> 
>> 
>>> 
>>> -----Original Message-----
>>> From: Oberon [mailto:oberon-bounces at lists.inf.ethz.ch] On Behalf Of
>>> Paul Reed
>>> Sent: Sunday, 16 February 2020 10:38 PM
>>> To: ETH Oberon and related systems
>>> Subject: Re: [Oberon] Module aliases - what is the correct way to
>>> handle them
>>> 
>>> Hi Chris,
>>> 
>>>> I think that the language spec does have such a restriction. In one
>>> M0
>>>> is a module alias, in the other M0 is an actual module name. A
>>> single
>>>> identifier (i.e. M0) can't be used for two different purposes in
>>> the
>>>> same scope... the report says nothing about the order in which the
>>>> import list should be processed.
>>>> IMPORT Z := M0, M0 := M1 ... Should be treated identically to
>>> IMPORT
>>>> M0 := M1, Z := M0
>>> 
>>> Thanks, and (I'm sorry if this is boring for everyone else) now I'm
>>> beginning to see that Jorg and I are thinking one way and you and
>>> Andreas are perhaps thinking another, which has helped me understand
>>> where the complications have come in.
>>> 
>>> I don't have a problem with the above being switched around because I
>>> (and Jorg) see the aliases and the canonical module names as
>>> different things.  I think you and Andreas are allowing a module
>>> alias to appear on the right hand side of an alias definition, but I
>>> wouldn't.  What's right?
>>> 
>> 
>> No - I agree with you. I was just pointing out that if aliases were allowed
>> on the right hand side of an alias definition it could result in ambiguous
>> import lists.
>> 
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> 
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