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| author | Zefram <zefram@fysh.org> | 2020-02-07 11:49:07 +0000 |
|---|---|---|
| committer | Karl Williamson <khw@cpan.org> | 2020-03-12 22:34:26 -0600 |
| commit | 4bd78a4962edb4f91c34534af5ee89fe47594c18 (patch) | |
| tree | 6114f58d702075348639cb19ff969974a82238ea /pod/perlop.pod | |
| parent | e8a86671097b355fe5e0d9da2473a926929d87c4 (diff) | |
| download | perl-4bd78a4962edb4f91c34534af5ee89fe47594c18.tar.gz | |
pod/perlop.pod: cross-precedence chaining
Warn explicitly that chainable operators don't chain with operators of
different precedence.
Diffstat (limited to 'pod/perlop.pod')
| -rw-r--r-- | pod/perlop.pod | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/pod/perlop.pod b/pod/perlop.pod index 9dc927804f..416b844fd2 100644 --- a/pod/perlop.pod +++ b/pod/perlop.pod @@ -60,8 +60,9 @@ special evaluation rules that can result in an operand not being evaluated at all; in general, the top-level operator in an expression has control of operand evaluation. -Some comparison operators, as their associativity, I<chain> with others -of the same precedence. This means that each comparison is performed +Some comparison operators, as their associativity, I<chain> with some +operators of the same precedence (but never with operators of different +precedence). This chaining means that each comparison is performed on the two arguments surrounding it, with each interior argument taking part in two comparisons, and the comparison results are implicitly ANDed. Thus S<C<"$a E<lt> $b E<lt>= $c">> behaves exactly like S<C<"$a E<lt> @@ -562,6 +563,8 @@ X<< ge >> A sequence of relational operators, such as S<C<"$a E<lt> $b E<lt>= $c">>, performs chained comparisons, in the manner described above in the section L</"Operator Precedence and Associativity">. +Beware that they do not chain with equality operators, which have lower +precedence. =head2 Equality Operators X<equality> X<equal> X<equals> X<operator, equality> @@ -585,6 +588,8 @@ X<ne> A sequence of the above equality operators, such as S<C<"$a == $b == $c">>, performs chained comparisons, in the manner described above in the section L</"Operator Precedence and Associativity">. +Beware that they do not chain with relational operators, which have +higher precedence. Binary C<< "<=>" >> returns -1, 0, or 1 depending on whether the left argument is numerically less than, equal to, or greater than the right |