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Diffstat (limited to 'pod/perlhack.pod')
| -rw-r--r-- | pod/perlhack.pod | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/pod/perlhack.pod b/pod/perlhack.pod index f2109bb6bd..efa3344394 100644 --- a/pod/perlhack.pod +++ b/pod/perlhack.pod @@ -2404,9 +2404,9 @@ therefore more ways for things to go wrong. You should try it. Introducing (non-read-only) globals Do not introduce any modifiable globals, truly global or file static. -They are bad form and break multithreading. The right way is to -introduce them as new interpreter variables, see F<intrpvar.h> (at the -very end for binary compatibility). +They are bad form and complicate multithreading and other forms of +concurrency. The right way is to introduce them as new interpreter +variables, see F<intrpvar.h> (at the very end for binary compatibility). Introducing read-only (const) globals is okay, as long as you verify with e.g. C<nm libperl.a|egrep -v ' [TURtr] '> (if your C<nm> has @@ -2417,12 +2417,17 @@ If you want to have static strings, make them constant: static const char etc[] = "..."; -If you want to have arrays of static strings, note carefully +If you want to have arrays of constant strings, note carefully the right combination of C<const>s: static const char * const yippee[] = {"hi", "ho", "silver"}; +There is a way to completely hide any modifiable globals (they are all +moved to heap), the compilation setting C<-DPERL_GLOBAL_STRUCT_PRIVATE>. +It is not normally used, but can be used for testing, read more +about it in L<perlhack>. + =item * Not exporting your new function |