Perl debugger is interactively using features

LanX has asked for the wisdom of the Perl Monks concerning the following question:

Hi,

I tested on two different installations that the debugger is activating a bunch of features when using it interactively.

I suppose it's doing a use VERSION internally activating features

It's kind of surprising because I provided a -e and not a -E in the prompt.

Is this documented behavior and if not shouldn't it be?

~$ perl -de0

Loading DB routines from perl5db.pl version 1.77
Editor support available.

Enter h or 'h h' for help, or 'man perldebug' for more help.

main::(-e:1):    0
  DB<1> p $]
5.038002
  DB<2> use B::Deparse

  DB<3> p B::Deparse->new->coderef2text(sub{})
{
    use feature 'current_sub', 'bitwise', 'evalbytes', 'fc', 'isa', 'm
+odule_true', 'postderef_qq', 'say', 'signatures', 'state', 'unicode_s
+trings', 'unicode_eval';
    
}
  DB<4>
[download]

Cheers Rolf
_{(addicted to the Perl Programming Language :)

see Wikisyntax for the Monastery}

Comment on Perl debugger is interactively using features Select or Download Code

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Re: Perl debugger is interactively using features by ikegami (Patriarch) on Jun 10, 2025 at 18:39 UTC
It's the result of the following in `perl5db.pl`: `BEGIN { require feature; $^V =~ /^v(\d+\.\d+)/; feature->import(":$1"); $_initial_cwd = Cwd::getcwd(); }` [download] (On a side note, it's pretty silly you can't do `use feature $^V;`.)	[reply] [d/l] [select]
Re^2: Perl debugger is interactively using features by LanX (Saint) on Jun 10, 2025 at 20:21 UTC
Do you know since which version this is in the code? Cheers Rolf _{(addicted to the Perl Programming Language :) see Wikisyntax for the Monastery}	[reply]
Re^3: Perl debugger is interactively using features by tonyc (Hermit) on Jun 10, 2025 at 23:22 UTC
It was added in 5.16.0 and documented in perldelta	[reply]
Re^4: Perl debugger is interactively using features by LanX (Saint) on Jun 10, 2025 at 23:24 UTC
Re: Perl debugger is interactively using features by LanX (Saint) on Jun 11, 2025 at 11:23 UTC
I just checked again: `perldebug` mentions the word "interactive" 13 times but never "features" Shouldn't this interactive feature be documented? The -E commandline switch (capital E) was added in 5.10. Shouldn't the debugger's rather depend on the -e or -E switch? Thanks. Cheers Rolf _{(addicted to the Perl Programming Language :) see Wikisyntax for the Monastery}	[reply]