diff options
Diffstat (limited to 'pod/perldiag.pod')
| -rw-r--r-- | pod/perldiag.pod | 45 |
1 files changed, 30 insertions, 15 deletions
diff --git a/pod/perldiag.pod b/pod/perldiag.pod index 2c675fdc94..61d1ee8805 100644 --- a/pod/perldiag.pod +++ b/pod/perldiag.pod @@ -104,7 +104,7 @@ really meant to multiply a glob by the result of calling a function. (W ambiguous) You wrote something like C<@{foo}>, which might be asking for the variable C<@foo>, or it might be calling a function named foo, and dereferencing it as an array reference. If you wanted -the varable, you can just write C<@foo>. If you wanted to call the +the variable, you can just write C<@foo>. If you wanted to call the function, write C<@{foo()}> ... or you could just not have a variable and a function with the same name, and save yourself a lot of trouble. @@ -1475,6 +1475,16 @@ workarounds. (F) The method which overloads "=" is buggy. See L<overload/Copy Constructor>. +=item &CORE::%s cannot be called directly + +(F) You tried to call a subroutine in the C<CORE::> namespace +with C<&foo> syntax or through a reference. The subroutines +in this package cannot yet be called that way, but must be +called as barewords. Something like this will work: + + BEGIN { *shove = \&CORE::push; } + shove @array, 1,2,3; # pushes on to @array + =item CORE::%s is not a keyword (F) The CORE:: namespace is reserved for Perl keywords. @@ -1517,21 +1527,26 @@ array is empty, just use C<if (@array) { # not empty }> for example. =item defined(%hash) is deprecated -(D deprecated) C<defined()> is not usually useful on hashes, because it -is not a reliable check for anything. Sometimes it returns true on -an empty hash, and sometimes false. If a non-empty check is what you -want then just use: +(D deprecated) C<defined()> is not usually right on hashes and has been +discouraged since 5.004. + +Although C<defined %hash> is false on a plain not-yet-used hash, it +becomes true in several non-obvious circumstances, including iterators, +weak references, stash names, even remaining true after C<undef %hash>. +These things make C<defined %hash> fairly useless in practice. + +If a check for non-empty is what you wanted then just put it in boolean +context (see L<perldata/Scalar values>): if (%hash) { # not empty } -If you had C<defined(%Foo::Bar::QUUX)> to check whether such a -package variable exists, then it has never actually done that, -but instead creates the hash if necessary (autovivification) -then tests for non-empty. If you really want to check -existence of a package variable then look at the glob slot -with C<defined *Foo::Bar::QUUX{HASH}> (see L<perlref>). +If you had C<defined %Foo::Bar::QUUX> to check whether such a package +variable exists then that's never really been reliable, and isn't +a good way to enquire about the features of a package, or whether +it's loaded, etc. + =item (?(DEFINE)....) does not allow branches in regex; marked by <-- HERE in m/%s/ @@ -1959,14 +1974,14 @@ earlier in the line, and you really meant a "less than". (W overflow) You called C<gmtime> with a number that was larger than it can reliably handle and C<gmtime> probably returned the wrong -date. This warning is also triggered with nan (the special +date. This warning is also triggered with NaN (the special not-a-number value). =item gmtime(%f) too small (W overflow) You called C<gmtime> with a number that was smaller than it can reliably handle and C<gmtime> probably returned the wrong -date. This warning is also triggered with nan (the special +date. This warning is also triggered with NaN (the special not-a-number value). =item Got an error from DosAllocMem @@ -2461,14 +2476,14 @@ L<perlfunc/listen>. (W overflow) You called C<localtime> with a number that was larger than it can reliably handle and C<localtime> probably returned the -wrong date. This warning is also triggered with nan (the special +wrong date. This warning is also triggered with NaN (the special not-a-number value). =item localtime(%f) too small (W overflow) You called C<localtime> with a number that was smaller than it can reliably handle and C<localtime> probably returned the -wrong date. This warning is also triggered with nan (the special +wrong date. This warning is also triggered with NaN (the special not-a-number value). =item Lookbehind longer than %d not implemented in regex m/%s/ |