exists

Tied-hash membership test: does a key exist in %Config?

תקציר

if (exists $Config{useithreads}) { ... }

מה מוחזר

A true value when the key is part of the configuration (even if the recorded value is undef), false otherwise.

דוגמאות

use Config;
print exists $Config{d_fork}       ? "yes" : "no";  # yes
print exists $Config{nonesuch}     ? "yes" : "no";  # no
print exists $Config{useithreads}  ? "yes" : "no";  # yes (value is undef)

מקרי קצה

• Pair EXISTS with FETCH to distinguish ”key is absent“ from ”key is present but undef“.

הבדלים מן ה-upstream

Fully compatible with upstream.