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digitalmars.D.learn - auto functions not authorized inside main?

reply Philippe Sigaud <philippe.sigaud gmail.com> writes:
Is it defined somewhere that auto functions are not authorized inside main?

void main()
{
    auto fun(string s) { return s;} // this does not compile
}

error:

main.d|6|found 's' when expecting ')'|
main.d|6|semicolon expected, not ')'|
main.d|6|found ')' instead of statement|
main.d|7|unrecognized declaration|
||=== Build finished: 4 errors, 0 warnings ===|


So it's not even parsed?

I couldn't find a bugzilla entry for this and I cannot believe no one ever
tried to put an auto fun inside main!

Is that part of the spec?

Philippe
Jun 27 2010
next sibling parent bearophile <bearophileHUGS lycos.com> writes:
Philippe Sigaud:

 I couldn't find a bugzilla entry for this and I cannot believe no one ever
 tried to put an auto fun inside main!


Maybe auto funcs are seen as instantiated templates, and templates can't be
defined inside functions. Anyway, I think you can file this as enhancement
request.

Bye,
bearophile
Jun 27 2010
prev sibling next sibling parent reply "Rory McGuire" <rmcguire neonova.co.za> writes:
On Sun, 27 Jun 2010 17:17:25 +0200, Philippe Sigaud  
<philippe.sigaud gmail.com> wrote:


 Is it defined somewhere that auto functions are not authorized inside  
 main?

 void main()
 {
     auto fun(string s) { return s;} // this does not compile
 }

 error:

 main.d|6|found 's' when expecting ')'|
 main.d|6|semicolon expected, not ')'|
 main.d|6|found ')' instead of statement|
 main.d|7|unrecognized declaration|
 ||=== Build finished: 4 errors, 0 warnings ===|


 So it's not even parsed?

 I couldn't find a bugzilla entry for this and I cannot believe no one  
 ever
 tried to put an auto fun inside main!

 Is that part of the spec?

 Philippe


Hope this isn't a stupid question, but how would you access this function  
if it did work?
Would it be fun("asdf")?
Is this just shorthand for:
auto fun = function(string s) {return s;};



-Rory
Jun 28 2010
parent reply BCS <none anon.com> writes:
Hello Rory,


 On Sun, 27 Jun 2010 17:17:25 +0200, Philippe Sigaud
 <philippe.sigaud gmail.com> wrote:
 

 void main()
 {
 auto fun(string s) { return s;} // this does not compile
 }


 Hope this isn't a stupid question, but how would you access this
 function
 if it did work?
 Would it be fun("asdf")?
 Is this just shorthand for:
 auto fun = function(string s) {return s;};


I would look almost the same to the user but should in fact be a normal local 
function.

-- 
... <IXOYE><
Jun 28 2010
parent "Rory McGuire" <rmcguire neonova.co.za> writes:
On Mon, 28 Jun 2010 16:01:46 +0200, BCS <none anon.com> wrote:


 Hello Rory,


 On Sun, 27 Jun 2010 17:17:25 +0200, Philippe Sigaud
 <philippe.sigaud gmail.com> wrote:


 void main()
 {
 auto fun(string s) { return s;} // this does not compile
 }


 Hope this isn't a stupid question, but how would you access this
 function
 if it did work?
 Would it be fun("asdf")?
 Is this just shorthand for:
 auto fun = function(string s) {return s;};


 I would look almost the same to the user but should in fact be a normal  
 local function.


Ye I got it now.

My brain was interpreting it as a delegate that wasn't being assigned to  
anything for some reason.

Now I get that it is just return type inferance doesn't work for inner  
functions.

-Rory
Jun 28 2010
prev sibling parent "Rory McGuire" <rmcguire neonova.co.za> writes:
On Mon, 28 Jun 2010 16:07:43 +0200, Philippe Sigaud  
<philippe.sigaud gmail.com> wrote:


 On Mon, Jun 28, 2010 at 15:40, Rory McGuire <rmcguire neonova.co.za>  
 wrote:



 void main()
 {
    auto fun(string s) { return s;} // this does not compile
 }








 Hope this isn't a stupid question, but how would you access this  
 function if it did work?
 Would it be fun("asdf")?





 Yes, that's what I had in mind. Basically, just using it as any other  
 auto inner function.



 void main()
 {
 auto fun(string s) { return s;}
 auto s = fun("abc");
 auto t = fun("def");
 }


 Is this just shorthand for:
 auto fun = function(string s) {return s;};





 That'd be about the same, yes. Fact is, I don't really _need_ this, I  
 was just astonished to be bitten by this.
 Why can I do



 void main()
 {
    string foo(string s) { return s;}
 }



 and not



 void main()
 {
    auto foo(string s) { return s;}
 }



 ?



 ***



 OK, I tested it some more, and it seems you cannot define auto function  
 inside any other function. So auto function cannot be inner functions.  
 I'm quite astonished I never did that when using D, but OK.








 Philippe





Right! I get what you're saying, didn't realise because it was formatted  
more how I would format a anon delegate.
You're saying "surely the compiler can infer the return type for a inner  
function just as much as it can infer the return type of a normal function.

Must be a compiler bug.

-Rory
Jun 28 2010