[ nice-Bugs-866853 ] ?t20 incorrect return type

Bugs item #866853, was opened at 2003-12-29 01:40
Message generated for change (Comment added) made by bonniot
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=112788&aid=866853&group_id=12788

Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Isaac Gouy (igouy)
Assigned to: Nobody/Anonymous (nobody)
Summary: ?t20 incorrect return type

Initial Comment:
Unsure if this is a bug or incorrect use.

interface ReadablePropertyMap <Key,Value>  {
  ?Value get(Key k);
}

class hash_property_map <A,B> 
implements ReadablePropertyMap <A,B> {

   HashMap<A,B> data = new HashMap();

   get(k) = data.get(k); // line 10 ***
}


\Nice\graph_test\..\graph_test\hash_property_map.nice:
 line 10, column 13:
Incorrect return type:
Found   : ?t20
Expected: ?Value

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>Comment By: Daniel Bonniot (bonniot)
Date: 2004-01-17 17:01

Message:
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user_id=88952

Sorry for the wrong advice. At the moment, you should resort
to defining the method outside the class, and explain that
the result type is alwys an option type:

interface ReadablePropertyMap <Key,Value> {
  //?Value get(Key k);
}
<Key,Value,V | Value <: ?V> ?V
get(ReadablePropertyMap<Key,Value>, Key k);


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Comment By: Isaac Gouy (igouy)
Date: 2003-12-29 14:37

Message:
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user_id=536291

That gives:
I:\pls\Nice\graph_test>nicec --sourcepath .. -a t.jar 
graph_test
nice.lang: parsing
graph_test: parsing

\Nice\graph_test\..\graph_test\hash_property_map.nice: line 
1, column 43:
Constraints on type parameters should all be specified in the 
prefix constraint

And this gives the ?t20 error again:
<Key,!Value> interface ReadablePropertyMap <Key,Value>  {
  ?Value get(Key k);
}


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Comment By: Daniel Bonniot (bonniot)
Date: 2003-12-29 11:11

Message:
Logged In: YES 
user_id=88952

Same kind of issue. The treatment of marker on type variables 
will definitely need some polishing.

In this case I think the correct definition would be:

<Key,Value> interface ReadablePropertyMap <Key,!Value> {
?Value get(Key k);
}


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Comment By: Isaac Gouy (igouy)
Date: 2003-12-29 01:41

Message:
Logged In: YES 
user_id=536291

Nice compiler version 0.9.6 prerelease (build 2003.12.28, 
21:41:54 UTC)

----------------------------------------------------------------------

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