1 files changed, 140 insertions, 0 deletions
diff --git a/lib/MDK/Common/Various.pm b/lib/MDK/Common/Various.pm
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+package MDK::Common::Various;
+
+=head1 NAME
+
+MDK::Common::Various - miscellaneous functions
+
+=head1 SYNOPSIS
+
+    use MDK::Common::Various qw(:all);
+
+=head1 EXPORTS
+
+=over 
+
+=item first(LIST)
+
+returns the first value. C<first(XXX)> is an alternative for C<((XXX)[0])>
+
+=item second(LIST)
+
+returns the second value. C<second(XXX)> is an alternative for C<((XXX)[1])>
+
+=item top(LIST)
+
+returns the last value. C<top(@l)> is an alternative for C<$l[$#l]>
+
+=item to_bool(SCALAR)
+
+returns a value in { 0, 1 }
+
+=item to_int(STRING)
+
+extracts the number from the string. You could use directly C<int "11 foo">, but
+you'll get I<Argument "11 foo" isn't numeric in int>. It also handles returns
+11 for C<"foo 11 bar">
+
+=item to_float(STRING)
+
+extract a decimal number from the string
+
+=item bool2text(SCALAR)
+
+returns a value in { "true", "false" }
+
+=item bool2yesno(SCALAR)
+
+returns a value in { "yes", "no" }
+
+=item text2bool(STRING)
+
+inverse of C<bool2text> and C<bool2yesno>
+
+=item chomp_(STRING)
+
+non-mutable version of chomp: do not modify the argument, returns the chomp'ed
+value. Also works on lists: C<chomp_($a, $b)> is equivalent to 
+C<chomp($a) ; chomp($b) ; ($a,$b)>
+
+=item backtrace()
+
+returns a string describing the backtrace. eg: 
+
+    sub g { print "oops\n", backtrace() }
+    sub f { &g }
+    f();
+
+gives
+
+    oops
+    main::g() called from /tmp/t.pl:2
+    main::f() called from /tmp/t.pl:4
+
+
+=item internal_error(STRING)
+
+another way to C<die> with a nice error message and a backtrace
+
+=item noreturn()
+
+use this to ensure nobody uses the return value of the function. eg:
+
+    sub g { print "g called\n"; noreturn }
+    sub f { print "g returns ", g() }
+    f();
+
+gives
+
+    test.pl:3: main::f() expects a value from main::g(), but main::g() doesn't return any value
+
+=back
+
+=head1 SEE ALSO
+
+L<MDK::Common>
+
+=cut
+  
+
+use Exporter;
+our @ISA = qw(Exporter);
+our @EXPORT_OK = qw(first second top to_bool to_int to_float bool2text bool2yesno text2bool chomp_ backtrace internal_error noreturn);
+our %EXPORT_TAGS = (all => [ @EXPORT_OK ]);
+
+
+sub first { $_[0] }
+sub second { $_[1] }
+sub top { $_[-1] }
+
+sub to_bool { $_[0] ? 1 : 0 }
+sub to_int { $_[0] =~ /\s*(\d*)/ && $1 }
+sub to_float { $_[0] =~ /\s*(\d*(\.\d*)?)/ && $1 }
+sub bool2text { $_[0] ? "true" : "false" }
+sub bool2yesno { $_[0] ? "yes" : "no" }
+sub text2bool { my $t = lc($_[0]); $t eq "true" || $t eq "yes" ? 1 : 0 }
+
+sub chomp_ { my @l = @_; chomp @l; wantarray() ? @l : $l[0] }
+
+sub backtrace() {
+    my $s;
+    for (my $i = 1; caller($i); $i++) {
+	my ($_package, $file, $line, $func) = caller($i);
+	$s .= "$func() called from $file:$line\n";
+    }
+    $s;
+}
+
+sub internal_error {
+    die "INTERNAL ERROR: $_[0]\n" . backtrace();
+}
+
+sub noreturn() {
+    if (defined wantarray()) {
+	my ($_package, $file, $line, $func) = caller(1);
+	my (undef, undef, undef, $func2) = caller(2);
+	die "$file:$line: $func2() expects a value from $func(), but $func() doesn't return any value\n";
+    }
+}
+
+1;
+