File perl-Carp-Assert.spec of Package perl-Carp-Assert

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File perl-Carp-Assert.spec of Package perl-Carp-Assert (Revision d67da36a11a243309ac4454ff1b7998f)

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#
# spec file for package perl-Carp-Assert
#
# Copyright (c) 2015 SUSE LINUX GmbH, Nuernberg, Germany.
#
# All modifications and additions to the file contributed by third parties
# remain the property of their copyright owners, unless otherwise agreed
# upon. The license for this file, and modifications and additions to the
# file, is the same license as for the pristine package itself (unless the
# license for the pristine package is not an Open Source License, in which
# case the license is the MIT License). An "Open Source License" is a
# license that conforms to the Open Source Definition (Version 1.9)
# published by the Open Source Initiative.

# Please submit bugfixes or comments via http://bugs.opensuse.org/
#

Name:           perl-Carp-Assert
Version:        0.21
Release:        0
%define cpan_name Carp-Assert
Summary:        executable comments
License:        Artistic-1.0 or GPL-1.0+
Group:          Development/Libraries/Perl
Url:            http://search.cpan.org/dist/Carp-Assert/
Source:         http://www.cpan.org/authors/id/N/NE/NEILB/%{cpan_name}-%{version}.tar.gz
BuildArch:      noarch
BuildRoot:      %{_tmppath}/%{name}-%{version}-build
BuildRequires:  perl
BuildRequires:  perl-macros
BuildRequires:  perl(Test::More) >= 0.88
%{perl_requires}

%description
    "We are ready for any unforseen event that may or may not 
    occur."
        - Dan Quayle

Carp::Assert is intended for a purpose like the ANSI C library
http://en.wikipedia.org/wiki/Assert.h. If you're already familiar with
assert.h, then you can probably skip this and go straight to the FUNCTIONS
section.

Assertions are the explicit expressions of your assumptions about the
reality your program is expected to deal with, and a declaration of those
which it is not. They are used to prevent your program from blissfully
processing garbage inputs (garbage in, garbage out becomes garbage in,
error out) and to tell you when you've produced garbage output. (If I was
going to be a cynic about Perl and the user nature, I'd say there are no
user inputs but garbage, and Perl produces nothing but...)

An assertion is used to prevent the impossible from being asked of your
code, or at least tell you when it does. For example:

# Take the square root of a number.
    sub my_sqrt {
        my($num) = shift;

# the square root of a negative number is imaginary.
        assert($num >= 0);

return sqrt $num;
    }

The assertion will warn you if a negative number was handed to your
subroutine, a reality the routine has no intention of dealing with.

An assertion should also be used as something of a reality check, to make
sure what your code just did really did happen:

open(FILE, $filename) || die $!;
    @stuff = <FILE>;
    @stuff = do_something(@stuff);

# I should have some stuff.
    assert(@stuff > 0);

The assertion makes sure you have some @stuff at the end. Maybe the file
was empty, maybe do_something() returned an empty list... either way, the
assert() will give you a clue as to where the problem lies, rather than 50
lines down at when you wonder why your program isn't printing anything.

Since assertions are designed for debugging and will remove themelves from
production code, your assertions should be carefully crafted so as to not
have any side-effects, change any variables, or otherwise have any effect
on your program. Here is an example of a bad assertation:

assert($error = 1 if $king ne 'Henry');  # Bad!

It sets an error flag which may then be used somewhere else in your
program. When you shut off your assertions with the $DEBUG flag, $error
will no longer be set.

Here's another example of *bad* use:

assert($next_pres ne 'Dan Quayle' or goto Canada);  # Bad!

This assertion has the side effect of moving to Canada should it fail. This
is a very bad assertion since error handling should not be placed in an
assertion, nor should it have side-effects.

In short, an assertion is an executable comment. For instance, instead of
writing this

# $life ends with a '!'
    $life = begin_life();

you'd replace the comment with an assertion which *enforces* the comment.

$life = begin_life();
    assert( $life =~ /!$/ );

%prep
%setup -q -n %{cpan_name}-%{version}

%build
%{__perl} Makefile.PL INSTALLDIRS=vendor
%{__make} %{?_smp_mflags}

%check
%{__make} test

%install
%perl_make_install
%perl_process_packlist
%perl_gen_filelist

%files -f %{name}.files
%defattr(-,root,root,755)
%doc Changes README

%changelog

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File perl-Carp-Assert.spec of Package perl-Carp-Assert (Revision d67da36a11a243309ac4454ff1b7998f)

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