NAME

Call::Context - Sanity-check calling context

SYNOPSIS

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

DISCUSSION

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.

FUNCTIONS

must_be_list()

die()s if the calling function is itself called outside list context. (See the SYNOPSIS for examples.)

must_not_be_scalar()

die()s if the calling function is itself called in scalar context. (See the SYNOPSIS for examples.)

EXCEPTIONS

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.

REPOSITORY

https://github.com/FGasper/p5-Call-Context