I'd like to construct a prototype which checks at compile time for a "real scalar value" instead of forcing scalar context.

Using (\$) excludes literals and there doesn't seem to be any alternative for constants to be included in ((\[$@%&*]))

(more details in docs for Prototypes)

some example code to make it clearer:

  DB<1> sub tst ($) { print @_}   # primitive approach
 
  DB<2> @a=qw/a b c/              
 
  DB<3> tst @a                    # NO! I don't want to force scalar c
+ontext on other datatypes
3
  DB<4> sub tst2 (\$) { print @_} # Restrict to scalars starting with 
+sigil "$"
 
  DB<5> tst2 @a                   # YES! at least there is no scalar c
+ontext
Type of arg 1 to main::tst2 must be scalar (not array dereference) at 
+(eval 11)[/usr/share/perl/5.10/perl5db.pl:638] line 2, at EOF<P><P>

  DB<6> tst2 "1"                  # NO! Constants are not allowed ... 
+sigh
Type of arg 1 to main::tst2 must be scalar (not constant item) at (eva
+l 9)[/usr/share/perl/5.10/perl5db.pl:638] line 2, at EOF
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Any ideas? Am I missing something?

(....I'm not really confident anyhow ...)

UPDATE: yeah I know that I still need to dereference with (\$), but that's not the point here.

UPDATE2: now that's confusing, isn't it?

  DB<9> print ref \"1"
SCALAR
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UPDATE3: (16:25 CEST) Is this a purely academic discussion? Don't think so, let me give you an example of a problem with the command join:

  DB<13> @a=qw/a b c/
 
  DB<14> print join ":",@a        # RIGHT
a:b:c
  DB<15> print join @a,":"        # NONSENSE  (at least in 99.9% of th
+e cases) but no error message
:
  DB<16> # What if I REALLY want the length as delimiter?
 
  DB<17> print join scalar @a,":" # well, in <0.1% of the usecases, yo
+u can afford to be explicit
:
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