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Feature request: implement $DB::method variable #16056

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p5pRT opened this issue Jun 28, 2017 · 4 comments
Open

Feature request: implement $DB::method variable #16056

p5pRT opened this issue Jun 28, 2017 · 4 comments
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distro-Linux type-core

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@p5pRT
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p5pRT commented Jun 28, 2017

Migrated from rt.perl.org#131674 (status was 'open')

Searchable as RT131674$
@p5pRT
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p5pRT commented Jun 28, 2017

From @KES777

Created by @KES777

When I want to debug return values from some subroutine I analize $DB​::sub
variable at DB​::sub. But faced into the problem when the method call is done.

[perldebguts](https://perldoc.perl.org/perldebguts.html) states​:

When execution of the program reaches **a subroutine call**,
a call to &DB​::sub (args) is made instead,
with $DB​::sub holding the name of the called subroutine

But when execution of the next program reaches 11 line​:

$cat $test.pl
package Test1;

sub t1 {};

package Test2;

push @​ISA, 'Test1';

package main;

Test2->t1; # <<<<<<< 11 line

The $DB​::sub contain `Test1​::t1` instead of expected `Test2​::t2`
when `Test2` do not implement `t1` method
And $DB​::sub contain `Test2​::t1` when `Test2` implement `t1` method

This stops me to setup breakpoint without knowing the hierarchy of
debugging object. (Complexity raises with multiple inheritance)

I understand that DOC describes **a subroutine call** but lack of `$DB​::method`
cause the inconvenience.

Please provide $DB​::method variable with value of called method

Perl Info 

Flags:
    category=core
    severity=low

Site configuration information for perl 5.24.1:

Configured by kes at Sun Apr 30 22:40:30 EEST 2017.

Summary of my perl5 (revision 5 version 24 subversion 1) configuration:
   
  Platform:
    osname=linux, osvers=4.4.0-53-generic, archname=x86_64-linux
    uname='linux kes-x751sa 4.4.0-53-generic #74-ubuntu smp fri dec 2 15:59:10 utc 2016 x86_64 x86_64 x86_64 gnulinux '
    config_args='-de -Dprefix=/home/kes/perl5/perlbrew/perls/perl-5.24.1 -Aeval:scriptdir=/home/kes/perl5/perlbrew/perls/perl-5.24.1/bin'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=undef, usemultiplicity=undef
    use64bitint=define, use64bitall=define, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2',
    cppflags='-fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include'
    ccversion='', gccversion='5.4.0 20160609', gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678, doublekind=3
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16, longdblkind=3
    ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t', lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -fstack-protector-strong -L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib/gcc/x86_64-linux-gnu/5/include-fixed /usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib
    libs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc
    perllibs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc
    libc=libc-2.23.so, so=so, useshrplib=false, libperl=libperl.a
    gnulibc_version='2.23'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -O2 -L/usr/local/lib -fstack-protector-strong'

Locally applied patches:
    Devel::PatchPerl 1.38


@INC for perl 5.24.1:
    /home/kes/perl5/perlbrew/perls/perl-5.24.1/lib/site_perl/5.24.1/x86_64-linux
    /home/kes/perl5/perlbrew/perls/perl-5.24.1/lib/site_perl/5.24.1
    /home/kes/perl5/perlbrew/perls/perl-5.24.1/lib/5.24.1/x86_64-linux
    /home/kes/perl5/perlbrew/perls/perl-5.24.1/lib/5.24.1


Environment for perl 5.24.1:
    HOME=/home/kes
    LANG=en_US.UTF-8
    LANGUAGE=en
    LC_ADDRESS=uk_UA.UTF-8
    LC_IDENTIFICATION=uk_UA.UTF-8
    LC_MEASUREMENT=uk_UA.UTF-8
    LC_MESSAGES=en_US.UTF-8
    LC_MONETARY=uk_UA.UTF-8
    LC_NAME=uk_UA.UTF-8
    LC_NUMERIC=uk_UA.UTF-8
    LC_PAPER=uk_UA.UTF-8
    LC_TELEPHONE=uk_UA.UTF-8
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/kes/perl5/perlbrew/bin:/home/kes/perl5/perlbrew/perls/perl-5.24.1/bin:/home/kes/bin:/home/kes/bin:/home/kes/bin:/home/kes/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
    PERLBREW=command perlbrew
    PERLBREW_BASHRC_VERSION=0.78
    PERLBREW_HOME=/home/kes/.perlbrew
    PERLBREW_MANPATH=/home/kes/perl5/perlbrew/perls/perl-5.24.1/man
    PERLBREW_PATH=/home/kes/perl5/perlbrew/bin:/home/kes/perl5/perlbrew/perls/perl-5.24.1/bin
    PERLBREW_PERL=perl-5.24.1
    PERLBREW_ROOT=/home/kes/perl5/perlbrew
    PERLBREW_VERSION=0.78
    PERL_BADLANG (unset)
    SHELL=/bin/bash

@p5pRT
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p5pRT commented Jun 28, 2017

From @KES777

bugreport.tar

@p5pRT
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p5pRT commented Jun 29, 2017

From zefram@fysh.org

KES wrote​:

When I want to debug return values from some subroutine I analize $DB​::sub
variable at DB​::sub. But faced into the problem when the method call is done.

This mechanism behaves precisely as I would expect​: Test1​::t1 is in
fact the subroutine being called, and $DB​::sub identifies it correctly.
If $DB​::sub were to say "Test2​::t1" instead, that would break debugging,
because there is no subroutine by that name.

Please provide $DB​::method variable with value of called method

At the point the call is made and invokes debugger hooks, there is no
distinction between a method call and a direct subroutine call. If you
really want to intercept method calls, you'll need to catch the op that
performs the method lookup. I'm not going to advise you how to do that​:
you'd only get further out of your depth.

This stops me to setup breakpoint without knowing the hierarchy of
debugging object. (Complexity raises with multiple inheritance)

I think that by "debugging object" you mean "the invocant". The ->can
method would seem to address this issue.

Please learn Perl before you report any more supposed bugs. Writing a
debugger is not the way to learn Perl​: it is an especially tricky task
that only expert Perl programmers should undertake.

-zefram

@p5pRT
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p5pRT commented Jun 29, 2017

The RT System itself - Status changed from 'new' to 'open'

@xenu xenu removed the affects-5.24 label Nov 19, 2021
@xenu xenu removed the Severity Low label Dec 29, 2021
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