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proto and multi

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Richard Hainsworth
June 29, 2020 17:29
proto and multi
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I have several multi methods.

All of them have the same first statement, then differ depending on the 

proto seems to be a way to factor out the common statement, and there is 
a phrase in the Documentation that * can affect the dispatch, viz:

"You can give the |proto| a function body, and place the |{*}| where you 
want the dispatch to be done. This can be useful when you have a "hole" 
in your routine that gives it different behavior depending on the 
arguments given:"

The docs give and example proto, but unfortunately, not how this works 
with other multi's.

So  I tried this:

class NewClass {
     has $.debug is rw = False;
     has $.value is rw = 'Initial value';

     proto method handle(|c ) {
         note "value is $.value" if $.debug;
         { * } }
     multi method handle(Str $s) {
         $.value = $s;
         say 'in string' }
     multi method handle(Positional @s) {
         $.value = @s[0];
         say 'in positional' }

my NewClass $x .= new;

$x.handle('hello world');
$x.handle(<hello world>);
$x.debug = True;
$x.handle('hello world');
$x.handle(<hello world>);

#raku test.raku
#value is Initial value
#value is Initial value

I am wondering how to use proto and {*}

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