| Call::Context(3pm) | User Contributed Perl Documentation | Call::Context(3pm) |
Call::Context - Sanity-check calling context
use Call::Context;
sub gives_a_list {
#Will die() if the context is not list.
Call::Context::must_be_list();
return (1, 2, 3);
}
gives_a_list(); # die()s: incorrect context (void)
my $v = gives_a_list(); # die()s: incorrect context (scalar)
my @list = gives_a_list(); # lives
#----------------------------------------------------------------------
sub scalar_is_bad {
#Will die() if the context is not list.
Call::Context::must_not_be_scalar();
return (1, 2, 3);
}
scalar_is_bad(); # lives
my $v = scalar_is_bad(); # die()s: incorrect context (scalar)
my @list = scalar_is_bad(); # lives
If your function only expects to return a list, then a call in some other context is, by definition, an error. The problem is that, depending on how the function is written, it may actually do something expected in testing, but then in production act differently.
"die()"s if the calling function is itself called outside list context. (See the SYNOPSIS for examples.)
"die()"s if the calling function is itself called in scalar context. (See the SYNOPSIS for examples.)
This module throws instances of "Call::Context::X". "Call::Context::X" is overloaded to stringify; however, to keep memory usage low, "overload" is not loaded until instantiation.
https://github.com/FGasper/p5-Call-Context
| 2022-10-13 | perl v5.34.0 |