txt: ## dist_zef-lizmat-P5caller.md
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  # NAME
  
  Raku port of Perl's caller() built-in
  
  # SYNOPSIS
  
  ```
  use P5caller;
  
  sub foo { bar }
  sub bar { say caller[3] }        # foo
  
  sub baz { say caller(:scalar) }  # GLOBAL
  my $package = caller
  
  ```
  
  # DESCRIPTION
  
  This module tries to mimic the behaviour of Perl's `caller` built-in as closely as possible in the Raku Programming Language.
  
  # ORIGINAL PERL 5 DOCUMENTATION
  
  ```
  caller EXPR
  caller  Returns the context of the current pure perl subroutine call. In
          scalar context, returns the caller's package name if there is a
          caller (that is, if we're in a subroutine or "eval" or "require")
          and the undefined value otherwise. caller never returns XS subs
          and they are skipped. The next pure perl sub will appear instead
          of the XS sub in caller's return values. In list context, caller
          returns
  
              # 0         1          2
              ($package, $filename, $line) = caller;
  
          With EXPR, it returns some extra information that the debugger
          uses to print a stack trace. The value of EXPR indicates how many
          call frames to go back before the current one.
  
              #  0         1          2      3            4
              ($package, $filename, $line, $subroutine, $hasargs,
  
              #  5          6          7            8       9         10
              $wantarray, $evaltext, $is_require, $hints, $bitmask, $hinthash)
               = caller($i);
  
          Here, $subroutine is the function that the caller called (rather
          than the function containing the caller). Note that $subroutine
          may be "(eval)" if the frame is not a subroutine call, but an
          "eval". In such a case additional elements $evaltext and
          $is_require are set: $is_require is true if the frame is created
          by a "require" or "use" statement, $evaltext contains the text of
          the "eval EXPR" statement. In particular, for an "eval BLOCK"
          statement, $subroutine is "(eval)", but $evaltext is undefined.
          (Note also that each "use" statement creates a "require" frame
          inside an "eval EXPR" frame.) $subroutine may also be "(unknown)"
          if this particular subroutine happens to have been deleted from
          the symbol table. $hasargs is true if a new instance of @_ was set
          up for the frame. $hints and $bitmask contain pragmatic hints that
          the caller was compiled with. $hints corresponds to $^H, and
          $bitmask corresponds to "${^WARNING_BITS}". The $hints and
          $bitmask values are subject to change between versions of Perl,
          and are not meant for external use.
  
          $hinthash is a reference to a hash containing the value of "%^H"
          when the caller was compiled, or "undef" if "%^H" was empty. Do
          not modify the values of this hash, as they are the actual values
          stored in the optree.
  
          Furthermore, when called from within the DB package in list
          context, and with an argument, caller returns more detailed
          information: it sets the list variable @DB::args to be the
          arguments with which the subroutine was invoked.
  
          Be aware that the optimizer might have optimized call frames away
          before "caller" had a chance to get the information. That means
          that caller(N) might not return information about the call frame
          you expect it to, for "N > 1". In particular, @DB::args might have
          information from the previous time "caller" was called.
  
          Be aware that setting @DB::args is best effort, intended for
          debugging or generating backtraces, and should not be relied upon.
          In particular, as @_ contains aliases to the caller's arguments,
          Perl does not take a copy of @_, so @DB::args will contain
          modifications the subroutine makes to @_ or its contents, not the
          original values at call time. @DB::args, like @_, does not hold
          explicit references to its elements, so under certain cases its
          elements may have become freed and reallocated for other variables
          or temporary values. Finally, a side effect of the current
          implementation is that the effects of "shift @_" can normally be
          undone (but not "pop @_" or other splicing, and not if a reference
          to @_ has been taken, and subject to the caveat about reallocated
          elements), so @DB::args is actually a hybrid of the current state
          and initial state of @_. Buyer beware.
  
  ```
  
  # PORTING CAVEATS
  
  In Perl, `caller` can return an 11 element list. In the Raku implementation only the first 4 elements are the same as in Perl: package, filename, line, subname. The fifth element is actually the `Sub` or `Method` object and as such provides further introspection possibilities not found in Perl.
  
  As there is no such thing as `scalar` or `list` context in Raku, one must specify a `:scalar` named parameter to emulate the scalar context return value.
  
  # AUTHOR
  
  Elizabeth Mattijsen [liz@raku.rocks](mailto:liz@raku.rocks)
  
  If you like this module, or what I’m doing more generally, committing to a [small sponsorship](https://github.com/sponsors/lizmat/) would mean a great deal to me!
  
  Source can be located at: <https://github.com/lizmat/P5caller> . Comments and Pull Requests are welcome.
  
  # COPYRIGHT AND LICENSE
  
  Copyright 2018, 2019, 2020, 2021, 2023 Elizabeth Mattijsen
  
  Re-imagined from Perl as part of the CPAN Butterfly Plan.
  
  This library is free software; you can redistribute it and/or modify it under the Artistic License 2.0.
  