in reply to Re^5: shift on empty array in list context broken
in thread shift on empty array in list context broken

> Would this affect the interpretation of the contexts?

No, the context of x is not propagated.

the [...,...] is imposing list context 

  DB<50> x [ shift @x, splice @x,0,1 ]
0  ARRAY(0x34a5270)
   0  undef

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to enforce scalar context I used a scalar assignment

  
DB<60> x [ ($a=shift @x), ($b=splice @x,0,1) ]

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if you have doubts enter a call to a sub which returns the context depending on wantarray

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery FootballPerl is like chess, only without the dice

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Re^7: shift on empty array in list context broken (show context)
by LanX (Saint) on Jul 17, 2019 at 11:59 UTC
    > if you have doubts enter a call to a sub which returns the context depending on wantarray

      DB<35> sub context { local $\="\n";print wantarray ? "list" : define
+d wantarray ? "scalar" : "void";() }

  DB<36> x [ ($a= context), (context) ]
scalar
list
0  ARRAY(0x3466930)
   0  undef
  DB<37>

    [download]

    Cheers Rolf
    (addicted to the Perl Programming Language :)
    Wikisyntax for the Monastery FootballPerl is like chess, only without the dice

[reply]
[d/l]

      Right, now I've gone a bit more towards a TAP approach, but I'm having difficulties getting my plans to run. So far I've got:

      C:\Users\Theseus\perlmonks\sopw\11102936>dmake test
C:\"Dwimperl\perl\bin\perl.exe" "-MExtUtils::Command::MM" "-MTest::Har
+ness" "-e" "undef *Test::Harness::Switches; test_harness(0, 'blib\lib
+', 'blib\arch')" t/*.t
t/00-load.t ....... # Testing SoPW_11102936 0.01, Perl 5.014002, C:\Dw
+imperl\perl\bin\perl.exe
t/00-load.t ....... ok
t/01-works.t ...... Not an ARRAY reference at C:\Users\Theseus\perlmon
+ks\sopw\11102936\blib\lib/SoPW_11102936.pm line 78.
t/01-works.t ...... 1/9 # Looks like you planned 9 tests but ran 1.
# Looks like your test exited with 255 just after 1.
t/01-works.t ...... Dubious, test returned 255 (wstat 65280, 0xff00)
Failed 8/9 subtests
t/manifest.t ...... skipped: Author tests not required for installatio
+n
t/pod-coverage.t .. skipped: Author tests not required for installatio
+n
t/pod.t ........... skipped: Author tests not required for installatio
+n

Test Summary Report
-------------------
t/01-works.t    (Wstat: 65280 Tests: 1 Failed: 0)
  Non-zero exit status: 255
  Parse errors: Bad plan.  You planned 9 tests but ran 1.
Files=5, Tests=2,  1 wallclock secs ( 0.05 usr +  0.05 sys =  0.09 CPU
+)
Result: FAIL
Failed 1/5 test programs. 0/2 subtests failed.
dmake:  Error code 255, while making 'test_dynamic'

      [download]

      The Module and Test as is:

      Read more... (3 kB)
      Read more... (1072 Bytes)

      fyi report bugs here in the thread is fine. I've not uploaded to cpan.

[reply]
[d/l]
[select]

      see Update

      Ok I've had another go. This time within the debugger and the output is leaning more towards concise. However, I am now unsure whether I have something that could relate to the issue or if it's because am still noobing DB.

      Apart from getting contexts out of kilter, there are a couple of issues. Firstly,( moved to new SoPW Should high traceDepth trace into debugger code? )

      Secondly, I get a 'panic' warning, about attempting to copy a freed scalar. So I'm in panic mode and posting this now, along with the trace I attempted. Its probably nothing right?

      Read more... (3 kB)

      Update Ok scratch that, I added use strict; Also, moved the 'Firstly' out to a new SoPW.

      Read more... (5 kB)

      After attempting to do as you suggested, and reading plenty (read not nearly enough) of documentation, I have a little more appreciation for the debugger and how it can be used. If not actually managing to get any closer to the OP.

      As for using wantarray to view the contexts, for a moment there I thought there was a void built-in.

      But I see now that they are word-strings being returned to represent contexts.

      documentation visited

[reply]
[d/l]
[select]
        Sorry, but what are you trying to show here?

        Cheers Rolf
        (addicted to the Perl Programming Language :)
        Wikisyntax for the Monastery FootballPerl is like chess, only without the dice

[reply]

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