On Fri, May 29, 2020 at 04:36:41PM -0700, ToddAndMargo via perl6-users wrote:
> On 2020-05-28 06:39, Peter Pentchev wrote:
> > On Wed, May 27, 2020 at 03:12:01PM -0700, ToddAndMargo via perl6-users
> > wrote:
> > > > On 2020-05-27 14:32, Andy Bach wrote:
> > > > > #!/usr/bin/env raku
> > > > > my Str $x;
> > > > > if $x.starts-with( "[" ) &&
> > > > > $x.contains( "]" )
> > > > > { say "Passed"; } else { say "Failed"; }
> > > > >
> > > > > K:\Windows\NtUtil>raku Contains.Test.pl6
> > > > > Cannot resolve caller starts-with(Str:U: Str:D); none of these
> > > > > signatures match
> > > > >
> > > > > (Cool:D: Cool:D $needle, :i(:$ignorecase)!, :m(:$ignoremark), *%_
> > > > > --> Bool)
> > > > > (Cool:D: Cool:D $needle, :m(:$ignoremark)!, *%_ --> Bool)
> > > > > (Cool:D: Cool:D $needle, *%_ --> Bool)
> > > > > (Str:D: Str:D $needle, :i(:$ignorecase)!, :m(:$ignoremark), *%_ -->
> > > > > Bool)
> > > > > (Str:D: Str:D $needle, :m(:$ignoremark)!, *%_ --> Bool)
> > > > > (Str:D: Str:D $needle, *%_ --> Bool)
> > > > > in block <unit> at Contains.Test.pl6 line 3
> > > > >
> > > > > > The function should just complain that the variable is not
> > > > > initialized.
> > > > >
> > >
> > >
> > > > Well, it is:
> > > > Cannot resolve caller starts-with(Str:U: Str:D);
> > > > ...
> > > > in block <unit> at Contains.Test.pl6 line 3
> > > >
> > > > it says:
> > > > For line 3:
> > > > if $x.starts-with( "[" )
> > > > looking for a possible method 'starts-with' with a signature of 2
> > > > params; an undefined string ('Str:U:') and a defined one ('Str:D:')
> > > > failed - here's the list of the possible signatures raku currently has
> > > > ..."
> > > >
> > > > I'd not be surprise if you could write your own "starts-with(Str:U:
> > > > Str:D); " method in raku and take care of this. You could probably even
> > > > have it "say"
> > > > You have an undefined String var in this call, not going to be able to
> > > > do much useful matching against that. Did you forget to initialize
> > > > something?
> > >
> > > Hi Andy,
> > >
> > > The function should just complain that you need to feed it an
> > > initialized value instead of sending you on a wild goose chase,
> >
> > It does say that you are trying to call "starts-with()" as a method on
> > a value of type Str:U (undefined string), and it cannot find such
> > a method. It also tells you what methods it can find.
> >
> > It gives the same error message no matter what types the function/method
> > can handle and no matter what type you are trying to call it on.
> > From that point on Raku kind of expects you to know what Str:U means and
> > that the :U part means "undefined". It would give the same *type* of
> > message if you were trying to call a method that only works on undefined
> > strings and you were trying to call it on a defined string, only then it
> > would say that it can't find such a method for Str:D. In the eyes of
> > Raku, these errors are of the same kind, and it has provided you with
> > the types.
>
> Hi Peter,
>
> No doubt it is operating as designed.
>
> It would be a lot more friendly if "Str:U" was
> changed to "Str:D". Oh please! Oh Please!Sorry, I don't really understand what you mean. "Str:U" means an undefined string - that's what you're calling .starts-with() on. "Str:D" means a defined string - that's what .starts-with() wants to operate on. What do you mean "change Str:U to Str:D" - the error message says "you invoked it on an undefined string, it wants to be invoked on a defined string", what do you want to change? Now, if you meant "change Str:U to 'an undefined string'", mmmm, what I was trying to explain is that the error message is generic, it covers any wrong calls of functions on any types... it does not really try to get into what the types are (it cannot, in the general case for any other type). G'luck, Peter -- Peter Pentchev r...@ringlet.net r...@debian.org p...@storpool.com PGP key: http://people.FreeBSD.org/~roam/roam.key.asc Key fingerprint 2EE7 A7A5 17FC 124C F115 C354 651E EFB0 2527 DF13
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