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.\" ========================================================================
.\"
.IX Title "Params::Util 3"
.TH Params::Util 3 "2006-11-01" "perl v5.8.8" "User Contributed Perl Documentation"
.SH "NAME"
Params::Util \- Simple, compact and correct param\-checking functions
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 2
\&  # Import some functions
\&  use Params::Util qw{_SCALAR _HASH _INSTANCE};
.Ve
.PP
.Vb 2
\&  # If you are lazy, or need a lot of them...
\&  use Params::Util ':ALL';
.Ve
.PP
.Vb 6
\&  sub foo {
\&      my $object  = _INSTANCE(shift, 'Foo') or return undef;
\&      my $image   = _SCALAR(shift)          or return undef;
\&      my $options = _HASH(shift)            or return undef;
\&      # etc...
\&  }
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\f(CW\*(C`Params::Util\*(C'\fR provides a basic set of importable functions that makes
checking parameters a hell of a lot easier
.PP
While they can be (and are) used in other contexts, the main point
behind this module is that the functions \fBboth\fR Do What You Mean,
and Do The Right Thing, so they are most useful when you are getting
params passed into your code from someone and/or somewhere else
and you can't really trust the quality.
.PP
Thus, \f(CW\*(C`Params::Util\*(C'\fR is of most use at the edges of your \s-1API\s0, where
params and data are coming in from outside your code.
.PP
The functions provided by \f(CW\*(C`Params::Util\*(C'\fR check in the most strictly
correct manner known, are documented as thoroughly as possible so their
exact behaviour is clear, and heavily tested so make sure they are not
fooled by weird data and Really Bad Things.
.PP
To use, simply load the module providing the functions you want to use
as arguments (as shown in the \s-1SYNOPSIS\s0).
.PP
To aid in maintainability, \f(CW\*(C`Params::Util\*(C'\fR will \fBnever\fR export by
default.
.PP
You must explicitly name the functions you want to export, or use the
\&\f(CW\*(C`:ALL\*(C'\fR param to just have it export everything (although this is not
recommended if you have any _FOO functions yourself with which future
additions to \f(CW\*(C`Params::Util\*(C'\fR may clash)
.SH "FUNCTIONS"
.IX Header "FUNCTIONS"
.ie n .Sh "_STRING $string"
.el .Sh "_STRING \f(CW$string\fP"
.IX Subsection "_STRING $string"
The \f(CW\*(C`_STRING\*(C'\fR function is intended to be imported into your
package, and provides a convenient way to test to see if a value is
a normal non-false string of non-zero length.
.PP
Note that this will \s-1NOT\s0 do anything magic to deal with the special
\&\f(CW'0'\fR false negative case, but will return it.
.PP
.Vb 2
\&  # '0' not considered valid data
\&  my $name = _STRING(shift) or die "Bad name";
.Ve
.PP
.Vb 2
\&  # '0' is considered valid data
\&  my $string = _STRING($_[0]) ? shift : die "Bad string";
.Ve
.PP
Please also note that this function expects a normal string. It does
not support overloading or other magic techniques to get a string.
.PP
Returns the string as a conveince if it is a valid string, or
\&\f(CW\*(C`undef\*(C'\fR if not.
.ie n .Sh "_IDENTIFIER $string"
.el .Sh "_IDENTIFIER \f(CW$string\fP"
.IX Subsection "_IDENTIFIER $string"
The \f(CW\*(C`_IDENTIFIER\*(C'\fR function is intended to be imported into your
package, and provides a convenient way to test to see if a value is
a string that is a valid Perl identifier.
.PP
Returns the string as a convenience if it is a valid identifier, or
\&\f(CW\*(C`undef\*(C'\fR if not.
.ie n .Sh "_CLASS $string"
.el .Sh "_CLASS \f(CW$string\fP"
.IX Subsection "_CLASS $string"
The \f(CW\*(C`_CLASS\*(C'\fR function is intended to be imported into your
package, and provides a convenient way to test to see if a value is
a string that is a valid Perl class.
.PP
This function only checks that the format is valid, not that the
class is actually loaded. It also assumes \*(L"normalised\*(R" form, and does
not accept class names such as \f(CW\*(C`::Foo\*(C'\fR or \f(CW\*(C`D'Oh\*(C'\fR.
.PP
Returns the string as a convenience if it is a valid class name, or
\&\f(CW\*(C`undef\*(C'\fR if not.
.ie n .Sh "_POSINT $integer"
.el .Sh "_POSINT \f(CW$integer\fP"
.IX Subsection "_POSINT $integer"
The \f(CW\*(C`_POSINT\*(C'\fR function is intended to be imported into your
package, and provides a convenient way to test to see if a value is
a positive integer (of any length).
.PP
Returns the value as a convience, or \f(CW\*(C`undef\*(C'\fR if the value is not a
positive integer.
.Sh "_SCALAR \e$scalar"
.IX Subsection "_SCALAR $scalar"
The \f(CW\*(C`_SCALAR\*(C'\fR function is intended to be imported into your package,
and provides a convenient way to test for a raw and unblessed
\&\f(CW\*(C`SCALAR\*(C'\fR reference, with content of non-zero length.
.PP
For a version that allows zero length \f(CW\*(C`SCALAR\*(C'\fR references, see
the \f(CW\*(C`_SCALAR0\*(C'\fR function.
.PP
Returns the \f(CW\*(C`SCALAR\*(C'\fR reference itself as a convenience, or \f(CW\*(C`undef\*(C'\fR
if the value provided is not a \f(CW\*(C`SCALAR\*(C'\fR reference.
.Sh "_SCALAR0 \e$scalar"
.IX Subsection "_SCALAR0 $scalar"
The \f(CW\*(C`_SCALAR0\*(C'\fR function is intended to be imported into your package,
and provides a convenient way to test for a raw and unblessed
\&\f(CW\*(C`SCALAR0\*(C'\fR reference, allowing content of zero\-length.
.PP
For a simpler \*(L"give me some content\*(R" version that requires non-zero
length, \f(CW\*(C`_SCALAR\*(C'\fR function.
.PP
Returns the \f(CW\*(C`SCALAR\*(C'\fR reference itself as a convenience, or \f(CW\*(C`undef\*(C'\fR
if the value provided is not a \f(CW\*(C`SCALAR\*(C'\fR reference.
.ie n .Sh "_ARRAY $value"
.el .Sh "_ARRAY \f(CW$value\fP"
.IX Subsection "_ARRAY $value"
The \f(CW\*(C`_ARRAY\*(C'\fR function is intended to be imported into your package,
and provides a convenient way to test for a raw and unblessed
\&\f(CW\*(C`ARRAY\*(C'\fR reference containing \fBat least\fR one element of any kind.
.PP
For a more basic form that allows zero length \s-1ARRAY\s0 references, see
the \f(CW\*(C`_ARRAY0\*(C'\fR function.
.PP
Returns the \f(CW\*(C`ARRAY\*(C'\fR reference itself as a convenience, or \f(CW\*(C`undef\*(C'\fR
if the value provided is not an \f(CW\*(C`ARRAY\*(C'\fR reference.
.ie n .Sh "_ARRAY0 $value"
.el .Sh "_ARRAY0 \f(CW$value\fP"
.IX Subsection "_ARRAY0 $value"
The \f(CW\*(C`_ARRAY0\*(C'\fR function is intended to be imported into your package,
and provides a convenient way to test for a raw and unblessed
\&\f(CW\*(C`ARRAY\*(C'\fR reference, allowing \f(CW\*(C`ARRAY\*(C'\fR references that contain no
elements.
.PP
For a more basic \*(L"An array of something\*(R" form that also requires at
least one element, see the \f(CW\*(C`_ARRAY\*(C'\fR function.
.PP
Returns the \f(CW\*(C`ARRAY\*(C'\fR reference itself as a convenience, or \f(CW\*(C`undef\*(C'\fR
if the value provided is not an \f(CW\*(C`ARRAY\*(C'\fR reference.
.ie n .Sh "_ARRAYLIKE $value"
.el .Sh "_ARRAYLIKE \f(CW$value\fP"
.IX Subsection "_ARRAYLIKE $value"
The \f(CW\*(C`_ARRAYLIKE\*(C'\fR function tests whether a given scalar value can respond to
array dereferencing.  If it can, the value is returned.  If it cannot,
\&\f(CW\*(C`_ARRAYLIKE\*(C'\fR returns \f(CW\*(C`undef\*(C'\fR.
.ie n .Sh "_HASH $value"
.el .Sh "_HASH \f(CW$value\fP"
.IX Subsection "_HASH $value"
The \f(CW\*(C`_HASH\*(C'\fR function is intended to be imported into your package,
and provides a convenient way to test for a raw and unblessed
\&\f(CW\*(C`HASH\*(C'\fR reference with at least one entry.
.PP
For a version of this function that allows the \f(CW\*(C`HASH\*(C'\fR to be empty,
see the \f(CW\*(C`_HASH0\*(C'\fR function.
.PP
Returns the \f(CW\*(C`HASH\*(C'\fR reference itself as a convenience, or \f(CW\*(C`undef\*(C'\fR
if the value provided is not an \f(CW\*(C`HASH\*(C'\fR reference.
.ie n .Sh "_HASH0 $value"
.el .Sh "_HASH0 \f(CW$value\fP"
.IX Subsection "_HASH0 $value"
The \f(CW\*(C`_HASH0\*(C'\fR function is intended to be imported into your package,
and provides a convenient way to test for a raw and unblessed
\&\f(CW\*(C`HASH\*(C'\fR reference, regardless of the \f(CW\*(C`HASH\*(C'\fR content.
.PP
For a simpler \*(L"A hash of something\*(R" version that requires at least one
element, see the \f(CW\*(C`_HASH\*(C'\fR function.
.PP
Returns the \f(CW\*(C`HASH\*(C'\fR reference itself as a convenience, or \f(CW\*(C`undef\*(C'\fR
if the value provided is not an \f(CW\*(C`HASH\*(C'\fR reference.
.ie n .Sh "_HASHLIKE $value"
.el .Sh "_HASHLIKE \f(CW$value\fP"
.IX Subsection "_HASHLIKE $value"
The \f(CW\*(C`_HASHLIKE\*(C'\fR function tests whether a given scalar value can respond to
hash dereferencing.  If it can, the value is returned.  If it cannot,
\&\f(CW\*(C`_HASHLIKE\*(C'\fR returns \f(CW\*(C`undef\*(C'\fR.
.ie n .Sh "_CODE $value"
.el .Sh "_CODE \f(CW$value\fP"
.IX Subsection "_CODE $value"
The \f(CW\*(C`_CODE\*(C'\fR function is intended to be imported into your package,
and provides a convenient way to test for a raw and unblessed
\&\f(CW\*(C`CODE\*(C'\fR reference.
.PP
Returns the \f(CW\*(C`CODE\*(C'\fR reference itself as a convenience, or \f(CW\*(C`undef\*(C'\fR
if the value provided is not an \f(CW\*(C`CODE\*(C'\fR reference.
.ie n .Sh "_CODELIKE $value"
.el .Sh "_CODELIKE \f(CW$value\fP"
.IX Subsection "_CODELIKE $value"
The \f(CW\*(C`_CODELIKE\*(C'\fR is the more generic version of \f(CW\*(C`_CODE\*(C'\fR. Unlike \f(CW\*(C`_CODE\*(C'\fR,
which checks for an explicit \f(CW\*(C`CODE\*(C'\fR reference, the \f(CW\*(C`_CODELIKE\*(C'\fR function
also includes things that act like them, such as blessed objects that
overload \f(CW'&{}'\fR.
.PP
Please note that in the case of objects overloaded with '&{}', you will
almost always end up also testing it in 'bool' context at some stage.
.PP
For example:
.PP
.Vb 7
\&  sub foo {
\&      my $coed1 = _CODELIKE(shift) or die "No code param provided";
\&      my $code2 = _CODELIKE(shift);
\&      if ( $code2 ) {
\&           print "Got optional second code param";
\&      }
\&  }
.Ve
.PP
As such, you will most likely always want to make sure your class has
at least the following to allow it to evaluate to true in boolean
context.
.PP
.Vb 2
\&  # Always evaluate to true in boolean context
\&  use overload 'bool' => sub () { 1 };
.Ve
.PP
Returns the callable value as a convenience, or \f(CW\*(C`undef\*(C'\fR if the
value provided is not callable.
.PP
Note \- This function was formerly known as _CALLABLE but has been renamed
for greater symmetry with the other _XXXXLIKE functions.
.PP
The use of _CALLABLE has been deprecated. It will continue to work, but
with a warning, until end\-2006, then will be removed.
.PP
I apologise for any inconvenience caused.
.ie n .Sh "_INVOCANT $value"
.el .Sh "_INVOCANT \f(CW$value\fP"
.IX Subsection "_INVOCANT $value"
This routine tests whether the given value is a valid method invocant.  If so,
the value itself is returned.  Otherwise, \f(CW\*(C`_INVOCANT\*(C'\fR returns \f(CW\*(C`undef\*(C'\fR.
.ie n .Sh "_INSTANCE $object\fP, \f(CW$class"
.el .Sh "_INSTANCE \f(CW$object\fP, \f(CW$class\fP"
.IX Subsection "_INSTANCE $object, $class"
The \f(CW\*(C`_INSTANCE\*(C'\fR function is intended to be imported into your package,
and provides a convenient way to test for an object of a particular class
in a strictly correct manner.
.PP
Returns the object itself as a convenience, or \f(CW\*(C`undef\*(C'\fR if the value
provided is not an object of that type.
.ie n .Sh "_SET \e@array, $class"
.el .Sh "_SET \e@array, \f(CW$class\fP"
.IX Subsection "_SET @array, $class"
The \f(CW\*(C`_SET\*(C'\fR function is intended to be imported into your package,
and provides a convenient way to test for set of at least one object of
a particular class in a strictly correct manner.
.PP
The set is provided as a reference to an \f(CW\*(C`ARRAY\*(C'\fR of objects of the
class provided.
.PP
For an alternative function that allows zero-length sets, see the
\&\f(CW\*(C`_SET0\*(C'\fR function.
.PP
Returns the \f(CW\*(C`ARRAY\*(C'\fR reference itself as a convenience, or \f(CW\*(C`undef\*(C'\fR if
the value provided is not a set of that class.
.ie n .Sh "_SET0 \e@array, $class"
.el .Sh "_SET0 \e@array, \f(CW$class\fP"
.IX Subsection "_SET0 @array, $class"
The \f(CW\*(C`_SET0\*(C'\fR function is intended to be imported into your package,
and provides a convenient way to test for a set of objects of a
particular class in a strictly correct manner, allowing for zero objects.
.PP
The set is provided as a reference to an \f(CW\*(C`ARRAY\*(C'\fR of objects of the
class provided.
.PP
For an alternative function that requires at least one object, see the
\&\f(CW\*(C`_SET\*(C'\fR function.
.PP
Returns the \f(CW\*(C`ARRAY\*(C'\fR reference itself as a convenience, or \f(CW\*(C`undef\*(C'\fR if
the value provided is not a set of that class.
.Sh "_HANDLE"
.IX Subsection "_HANDLE"
\&\fB\s-1EXPERIMENTAL:\s0 \s-1SUBJECT\s0 \s-1TO\s0 \s-1CHANGE\s0 \s-1OR\s0 \s-1POSSIBLE\s0 \s-1REMOVAL\s0\fR
.PP
The \f(CW\*(C`_HANDLE\*(C'\fR function is intended to be imported into your package,
and provides a convenient way to test whether or not a single scalar
value is a file handle.
.PP
Unfortunately, in Perl the definition of a file handle can be a little
bit fuzzy, so this function is likely to be somewhat imperfect (at first
anyway).
.PP
That said, it is implement as well or better than the other file handle
detectors in existance (and we stole from the best of them).
.SH "TO DO"
.IX Header "TO DO"
\&\- Add _CAN to help resolve the UNIVERSAL::can debacle
.PP
\&\- More comprehensive tests for _SET and _SET0
.PP
\&\- Would be nice if someone would re-implement in \s-1XS\s0 for me? (done'ish)
.PP
\&\- Would be even nicer if someone would demonstrate how the hell to
build a Module::Install dist of the ::Util dual Perl/XS type. :/
.PP
\&\- Implement an assertion-like version of this module, that dies on
error.
.PP
\&\- Implement a Test:: version of this module, for use in testing
.SH "SUPPORT"
.IX Header "SUPPORT"
Bugs should be reported via the \s-1CPAN\s0 bug tracker at
.PP
<http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Params\-Util>
.PP
For other issues, contact the author.
.SH "AUTHOR"
.IX Header "AUTHOR"
Adam Kennedy <adamk@cpan.org>
.SH "SEE ALSO"
.IX Header "SEE ALSO"
Params::Validate, <http://ali.as/>
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2005, 2006 Adam Kennedy.
.PP
This program is free software; you can redistribute
it and/or modify it under the same terms as Perl itself.
.PP
The full text of the license can be found in the
\&\s-1LICENSE\s0 file included with this module.
Creat By MiNi SheLL
Email: devilkiller@gmail.com