[ nice-Bugs-798312 ] local function param namespace

Bugs item #798312, was opened at 2003-08-31 16:37
Message generated for change (Comment added) made by igouy
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=112788&aid=798312&group_id=12788

Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Isaac Gouy (igouy)
Assigned to: Nobody/Anonymous (nobody)
Summary: local function param namespace

Initial Comment:
My guess is that this is a feature request?



These comments refer to the code in 

WordfreqIntermediateExample. 



I made the formatLine package function a local function 

(mainly so I could reuse the StringBuffer) and 

discovered that the parameter name 'word' clashed with 

the variable name 'word'. Of course, we can rename the 

parameter in some arbitrary way like 'wordX' (although 

the keyword parameters mean that's not so good and 

perhaps we need to go back and rename the local 

var...).





void main(String[] args){

   var String word;

...



   String formatLine(String wordX, Cell count){

...

      buffer.append(wordX);

...

   }



...   formatLine(wordX: e.getKey(), count: e.getValue()) 



}

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

>Comment By: Isaac Gouy (igouy)
Date: 2003-09-01 08:33

Message:
Logged In: YES 
user_id=536291

> more important to show different aspects of Nice

I agree! And its important to show a practical style.





> redeclaration of local variables is not allowed

Let me step through what surprises me:



This compiles:

   void main1(String[] args){

      void F(String word){}

      var String word;

   }



but this doesn't:

   void main2(String[] args){

      var String word;

      void F(String word){}

   }



   \test\t.nice: line 3, column 23:

   Symbol word is already defined.

   Previous definition: \test\t.nice: line 2, column 15



1) I hadn't realized declaration order mattered







   void main3(String[] args){

      word = "test";

      void F(String word){}

   }



   \test\t.nice: line 2, column 4:

   word is not declared



2) It seems that the parameter of functional F doesn't exist 

beyond the scope of F. So the name clash of main3 is 

surprising to me. (And of course I don't experience that name 

clash in other languages.)







   void main4(String[] args){

      word = "test";

      void F(){ var String word; }

   }



   \test\t.nice: line 2, column 4:

   word is not declared





   void main5(String[] args){

      var String word;

      void F(){ var String word; }

   }



   \test\t.nice: line 3, column 25:

   Symbol word is already defined.

   Previous definition: \test\t.nice: line 2, column 15



3) Same as #2 but with a variable local to F.





Given that the param and var are local to F, I only "expect" 

that they will have name clashes in that local scope.



Aside from the bad 'surprise', the main consequence is more 

debug/editing when a function is moved, and a 'forced' 

arbitrary naming of vars and params to get around the name 

clash (rather than express intent).



Nice compiler version 0.9.2 (build 2003.09.01, 08:24:05 UTC)



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

Comment By: Arjan Boeijink (arjanb)
Date: 2003-09-01 05:30

Message:
Logged In: YES 
user_id=688815

This is not a bug, redeclaration of local variables is not 

allowed because it mostly indicates an error or bad code 

practise.



BTW I changed the code in that example because it 

contained to much optimization tricks. I know the code comes 

form a benchmark but I think it's more important to show 

different aspects of Nice than showing how to squeeze out a 

few percent more perfomance.



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

Comment By: Daniel Bonniot (bonniot)
Date: 2003-09-01 01:27

Message:
Logged In: YES 
user_id=88952

Idem, please submit something we can copy paste and compile

(without "..."). It's also good if you can remove irrelevant

parts, so the code is as short as possible.



It's also not clear from your message was is the bug (you

seem to have to identifiers with the same name, isn't a

"clash" expected?), or what feature you request.

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

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