68 lines
2.6 KiB
Diff
68 lines
2.6 KiB
Diff
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From 3eb35b099f783db0ec40f0ca9f20fd1666c54cdb Mon Sep 17 00:00:00 2001
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From: Yves Orton <demerphq@gmail.com>
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Date: Thu, 30 Jan 2020 09:36:37 +0100
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Subject: [PATCH] perltie.pod: rework example code so EXTEND is a no-op
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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Most tied array implementations can and should NO-OP the EXTEND
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method, and the sample code should not conflate EXTEND with STORESIZE.
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EXTEND is actually less usefully used by the core than it could be
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as AvMAX() does not have an equivalent tied method. So we cannot
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check if we need to extend for a tied array.
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This is related to [rt.cpan.org #39196] / Issue #17496.
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Signed-off-by: Petr Písař <ppisar@redhat.com>
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---
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pod/perltie.pod | 18 +++++++++++++-----
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1 file changed, 13 insertions(+), 5 deletions(-)
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diff --git a/pod/perltie.pod b/pod/perltie.pod
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index 2d433e8204..1bb220691b 100644
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--- a/pod/perltie.pod
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+++ b/pod/perltie.pod
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@@ -301,7 +301,7 @@ spaces so we have a little more work to do here:
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croak "length of $value is greater than $self->{ELEMSIZE}";
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}
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# fill in the blanks
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- $self->EXTEND( $index ) if $index > $self->FETCHSIZE();
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+ $self->STORESIZE( $index ) if $index > $self->FETCHSIZE();
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# right justify to keep element size for smaller elements
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$self->{ARRAY}->[$index] = sprintf "%$self->{ELEMSIZE}s", $value;
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}
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@@ -351,16 +351,24 @@ X<EXTEND>
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Informative call that array is likely to grow to have I<count> entries.
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Can be used to optimize allocation. This method need do nothing.
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-In our example, we want to make sure there are no blank (C<undef>)
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-entries, so C<EXTEND> will make use of C<STORESIZE> to fill elements
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-as needed:
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+In our example there is no reason to implement this method, so we leave
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+it as a no-op. This method is only relevant to tied array implementations
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+where there is the possibility of having the allocated size of the array
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+be larger than is visible to a perl programmer inspecting the size of the
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+array. Many tied array implementations will have no reason to implement it.
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sub EXTEND {
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my $self = shift;
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my $count = shift;
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- $self->STORESIZE( $count );
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+ # nothing to see here, move along.
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}
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+B<NOTE:> It is generally an error to make this equivalent to STORESIZE.
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+Perl may from time to time call EXTEND without wanting to actually change
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+the array size directly. Any tied array should function correctly if this
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+method is a no-op, even if perhaps they might not be as efficient as they
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+would if this method was implemented.
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+
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=item EXISTS this, key
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X<EXISTS>
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--
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2.21.1
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