Suggestion: "new delegate" - delegates useable outside of the nesting function scope

[Markus Dangl]

> Implementing static closures in D would be an interesting proposition, as 
> they would technically be objects, though implicitly.  Then there's the 
> problem with RAII class references.  Consider something like:
> 
> char delegate() createFileReader(char[] fileName)
> {
>     auto File f = new File(fileName, FileMode.In);
> 
>     return new delegate char()
>     {
>         return f.getc();
>     };
> }
> 
> This function would return a function that would be used to read (very 
> simply) a file, one character at a time.  The problem is that the File 
> reference in the enclosing scope could not be deleted when createFileReader 
> returns.  I suppose the way around this would be to disallow using RAII 
> class references inside static closures, but.. 


You might find my "AdvancedDelegate" library useful, i recently posted 
it to the announce newsgroup. Using its templates for partial 
application of functions and delegates, you can do something very 
similiar to the code above:

AdvancedDelegate0!(char) createFileReader(char[] fileName)
{
     auto File f = new File(fileName, FileMode.In);

     auto readerFunc = AdvancedDelegate(
         function char(File f)
         {
             return f.getc();
         }
     );
     return readerFunc(f);
}