OpenEuphoria

Re: EuCOM : Attn Matt : String Return Value

• Posted by Matt Lewis <matthewwalkerlewis at ?mail?com> Oct 09, 2007
• 703 views

Pete Lomax wrote:
> 
> Matt Lewis wrote:
> > 
> > Actually, namespaces will be inherited (and are inherited, for code at the
> > head of the svn repository) in the next release.  I typically run this 
> > code, which is probably why I haven't noticed the bug.
> 
> Cool. How did you solve that in the end? In Positive I devised a set of
> priority
> tables, which is quite simple really but harder to explain, eg:
> 
> -- fileno  desc       parents	 priorities
> --   1	   inc7 	{}	{2,1,1,1,1,1}
> --   2	     eric	{1}	{2,4,3,3,3,3}
> --   3	       bob	{2}	{2,4,6,5}

<snip>

My technique is a bit different.  I don't worry about priorities.  Just the
'lineage' of each file.  Basically, I record who got included by whom.
Then, when doing a symbol lookup, if there are multiple matching global
symbols, I have to do some work.

If no namespace identifier is used:

I detect if a symbol is within or without the current file's include
tree.  If there is only one symbol from the include tree, and one or more
from without, then the one from within is selected.  This resolution will,
IMHO, solve 95% of the possible namespace conflicts with 3rd party libs.

If multiple symbols from within are identified, then an error results.  

If no symbols from within are identified, and multiple from without, an
error results

Now, when a namespace identifier is used:

If a symbol is not within the file (as specified by the namespace identifier), 
*or its include tree* then it is ignored.  If multiple symbols are found,
then an error results.  

This could, in theory, break some existing code, but given the dearth of 
namespacing in today's code base, I doubt that many would be affected. 
I suppose it is this situation which led you to the priority scheme, and
which might be useful in this case.

I suppose that giving preference to a symbol in the namespaced file (as
opposed to files included by that file) would also work to solve the 
dilemma.  It would be similar to having local symbols overriding globals
from other files.  If the user really needed to use the nested symbol,
then he could include whatever file it was and give it its own 
namespace.  A corner case, to be sure, but not inconceivable.

Matt