Scalar::Validation
Makes validation of scalar values or function (sub) parameters easy, is fast and uses pure Perl.
This documentation refers to version 0.610 of Scalar::Validation
use Scalar::Validation qw(:all); my $int_1 = validate int_1 => Int => 123; my $float_1 = validate float_1 => Float => 3.1415927; my $para_1 = par parameter_1 => -Range => [1,5] => Int => shift; my $exponent = npar -exponent => -Range => [1,5] => Int => \%options; my $para_2 = parameter parameter_1 => -Range => [1,5] => Int => shift; my $exponent_2 = named_parameter -exponent => -Range => [1,5] => Int => \%options; my $int_2 = validate (int_2 => -And => [Scalar => 'Int'], 123); my $int_3 = validate (int_3 => -Or => [Int => 'CodeRef'], 123); my $code_ref = validate (code_ref => -Or => [Int => 'CodeRef'], sub { 123; }); my $enum_abc = validate (parameter => -Enum => {a => 1, b => 1, c => 1}, 'c'); my $enum_abc = validate (parameter => -Enum => [ qw (a b c) ], 'c'); my $int_4 = validate (int_4 => -Optional => Int => undef); my $int_5 = validate (int_5 => -Optional => -And => [Scalar => Int => 0] => undef); my $int_6 = validate (int_6 => -Optional => -Or => [Int => CodeRef => 0] => undef); my $enum_2 = validate (enum_2 => -Optional => -Enum => {a => 1, b => 1, c => 1} => undef); my $range_1 = validate (range_1 => -Optional => -Range => [1,5] => Int => undef);
Just checks, never dies:
is_valid (valid_1 => Int => 123); # is valid, returns 1; is_valid (valid_2 => Int => 1.23); # is not valid, returns 0; is_valid (valid_3 => Int => 'a'); # is not valid, returns 0; is_valid (valid_4 => Int => undef); # is not valid, returns 0;
Free defined rules or wheres only (also for validate(...))
my $value = 2; # be careful, doesn't check that $_ is an integer! is_valid (free_where_greater_zero => sub { $_ && $_ > 0} => $value); # is valid, returns 1 is_valid (free_rule_greater_zero => { -as => Int => -where => sub { $_ > 0}, -message => sub { "$_ is not > 0" }, } => $value); # is valid, returns 1 my $my_rule = { -as => Int => -where => sub { $_ && $_ > 0} => -message => sub { "$_ is not > 0" }; is_valid (free_rule_greater_zero => $my_rule => $value); # is valid, returns 1
Managing Rules
declare_rule ( NegativeInt => -as => Int => # Parent rule is optional -where => sub { $_ < 0 }, -message => sub { "value $_ is not a negative integer" }, ); replace_rule ( NegativeInt => -as => Int => # Parent rule is optional -where => sub { $_ =< 0 }, -message => sub { "value $_ is not a negative integer" }, ); delete_rule ('NegativeInt'); rule_known(Unknown => 1); # returns 0 (false) rule_known(Negative => 1); # returns 1 (true)
Dynamic Rules For Comparison
par parameter => greater_than 4 => Int => shift; # = 5 validate parameter => g_t 4 => Int => $value; # = 6 is_valid (parameter => greater_equal 4 => Float => $value); # = 4.1 is_valid (parameter => g_e 4 => Int => $value); # = 4 npar -parameter => less_than 4 => Int => \%options; is_valid (parameter => l_t (4 => 'Float') => $value); # = 4.1 validate (parameter => less_equal (4 => 'Float') => $value); # = 4.1 is_valid (parameter => l_e 4 => Int => $value); # = 3 my $value = 'Text'; is_valid (parameter => equal_to (text => String) => lc($value)); # compares as String is_valid (parameter => equal_to (4 => String) => '4.0'); # not valid, compares as String is_valid (parameter => equal_to (4 => Float) => 4.0); # valid, compares as number is_valid (parameter => equal_to (4 => Int) => 4.0); # valid !!, compares as number
This class implements a fast and flexible validation for scalars. It is implemented functional to get speed and some problems using global rules for all ;).
Following validation functions exist:
validate(...); par(...); # Alias for validate() parameter(...); # Alias for validate() named_parameter(...); n_par(...); # Alias for named_parameter() is_valid(...);
Different names for same functionality. Use like
my $var_float = validate ('PI is a float' => Float => $PI); my $par_int = par (par_int => Int => shift);
First argument is a free name of the check done. If used as parameter check for subs it is the 'name' of the parameter.
Last argument holds the value to be checked. It has to be a scalar, and therefore the module was named Scalar::Validation.
Optional last argument: After the value argument can be added a sub to print out an own error message instead of the default error message:
my $var_float = validate ('PI is a float' => Float => $PI => sub { 'wrong defined $PI: '.$_ } );
All parameters after first before value argument are used to select or define "validation rules": 'Float' and 'Int' in this example.
These subs extract named parameters out of a parameter_hash_ref. Key and value will be deleted from hash during validation. After processing all parameters hash_ref should be empty.
my $par_1_int = npar (par_1 => Int => \%parameters); my $par_2_float = named_parameter (par_2 => Float => \%parameters);
First argument ($key) is the key of the parameter. Last argument ($parameters) has to be a hash_ref.
Without these subs you would have to implement for reading par_1:
my $key = 'par_1'; my $value = delete $parameters->{$key}; my $par_1_int = par ($key => Int => $value);
It could be done in one line, but this line will be complicated and not easy to understand. The key value is needed twice and that can cause Copy-Paste-Errors.
On default, application dies with error message, if data checked by named_parameter(...) or validate(...) is not valid.
named_parameter(...)
validate(...)
validate (parameter => -And => [Scalar => 'Int'], {} ); validate (parameter => -And => [Scalar => 'Int'], [] ); validate (parameter => -And => [Scalar => 'Int'], sub { 'abc'; });
is_valid(...) just does validation and returns 1 in case on success and 0 in case of fail.
is_valid(...)
print is_valid(parameter => -And => [Scalar => 'Int'], 123) ." => 123 is int\n"; print is_valid(parameter => -And => [Scalar => 'Int'], {} ) ." => {} is no scalar\n"; print is_valid(parameter => -And => [Scalar => 'Int'], [] ) ." => [] is no scalar\n"; print is_valid(parameter => -And => [Scalar => 'Int'], sub { 'abc'; }) ." => sub { 'abc'; } is no scalar\n";
If a validation fails and validation mode is not set as 'die', you probably will run in trouble afterwards, when you use invalid data.
Therefore do
local ($FSL::Validation::trouble_level) = 0; # add your code return undef if validation_trouble(); # fire exit, if validation does not die
or something similar.
is_valid(...) does not rise $trouble_level, as to be expected. All other validation subs do!
$trouble_level
Per default, no messages are stored to increase performance. To store messages, the message store has to be localized into an array_ref.
This is the only safe way to deal with recursive calls and die! So use a block like this to store messages
my @messages; { local ($Scalar::Validation::message_store) = []; my $result = is_valid(parameter => -And => [Scalar => 'Int'], {} ); @messages = @{validation_messages()} unless $result; }
Scalar::Validation can be also used a parameter check for unnamed and named parameters. parameters_end \@_; ensures, that all parameters are processed. Otherwise it rises the usual validation error. Shorthand: p_end.
parameters_end \@_;
p_end
sub create_some_polynom { local ($FSL::Validation::trouble_level) = 0; my $max_potenz = par maximum_potenz => -Range => [1,5] => Int => shift; # additional parameters ... p_end \@_; return undef if validation_trouble(); # fire exit, if validation does not die # --- run sub ------------------------------------------------- my $polynom = ''; map { $polynom .= " + ".int (100*rand())."*x^".($max_potenz-$_); } (0..$max_potenz); return $polynom; }; print create_some_polynom(1)."\n"; print create_some_polynom(2)."\n"; print create_some_polynom(3)."\n"; print create_some_polynom(4)."\n"; print create_some_polynom(5)."\n";
Dies by error message
print create_some_polynom("four")."\n"; print create_some_polynom(5.5)."\n"; print create_some_polynom(6)."\n"; print create_some_polynom(6, 1)."\n";
Named arguments can also be handled. This needs more runtime than the indexed variant.
convert_to_named_params() does a safe conversion by validate().
convert_to_named_params()
validate()
sub create_some_polynom_named { local ($FSL::Validation::trouble_level) = 0; my %pars = convert_to_named_params \@_; my $max_potenz = npar -maximum_potenz => -Range => [1,5] => Int => \%pars; # additional parameters ... parameters_end \%pars; return undef if validation_trouble(); # fire exit, if validation does not die # --- run sub ------------------------------------------------- my $polynom = ''; map { $polynom .= " + ".int (100*rand())."*x^".($max_potenz-$_); } (0..$max_potenz); return $polynom; }; print create_some_polynom_named(-maximum_potenz => 4);
You can and should create your own rules, i.e.
declare_rule ( Positive => -as => Int => # Parent rule is optional -where => sub { $_ >= 0 }, -message => sub { "value $_ is not a positive integer" }, ); rule_known(Unknown => 1); # returns 0 (false) rule_known(Positive => 1); # returns 1 (true)
The value to be validated is stored in variable $_. For
$_
-message => sub { "my message for wrong value $_."}
it is enclosed in single ticks, so that you get the following output for $_ = "Garfield":
$_ = "Garfield"
my message for wrong value 'Garfield'.
deletes_rule($rule) deletes rule $rule. It calls current validation fail method, if $rule not set or rule cannot be found.
deletes_rule($rule)
$rule
delete_rule ('NegativeInt');
replace_rule($rule = ...)> deletes rule $rule first and then declares it. Same arguments as for declare_rule;
replace_rule($rule =
replace_rule ( NegativeInt => -as => Int => # Parent rule is optional -where => sub { $_ =< 0 }, -message => sub { "value $_ is not a negative integer or 0" }, );
There are some special rules, that cannot be changed. Those rules start with an '-' char in front:
-Optional # value may be undefined. If not, use following rule -And # all rules must be ok -Or # at least one rule must be ok -Enum # for easy defining enumeration on the fly, by array_ref or hash_ref -Range # Intervall: [start, end] => type -RefEmpty # array_ref: scalar (@$array_ref) == 0 # hash_ref: scalar (keys %$hash_ref) == 0
Reason is, that they combine other rules or have more or different parameters than a "normal" rule or using own implementation just to speed up.
All normal rules should not start with a '-', but it is not forbidden to do so.
my $var_float = validate ('PI is a float' => -Optional => Float => $PI => sub { 'wrong defined $PI: '.$_ } );
This rule does not die, if $PI is undef because of -Optional in front.
You should not use Scalar::Validation direct in your code.
Better is creating an own module My::Validation, that adds the rules you need and only exports the subs the developers in your project should use:
use My::Validation; my $v = validate v => my_type => new MyType();
In this case My::Validation should create rules out of XML datatypes after reading in a XSD file. So rules are dynamic and your application can handle different XSD definitions without knowing something about XSD outside of this module.
Also you can filter XSD type contents, i.e. for enmuerations: Allowing not all possible values in UI or remove entries only for compatibility with old versions.
And your Application or GUI doesn't need to know about it.
There are 4 predefined validation modes:
die warn silent off
is_valid() uses a special validation mode independent from the followings. It will do the checks in every case.
is_valid()
The validation methods call croak "validation message"; in case of failures or a rule fails. Your script (or this part of your script) will die.
croak "validation message";
The validation methods call carp "validation message"; in case of failures or a rule fails. Your get warnings for every failed rule.
carp "validation message";
Your script (or this part of your script) will NOT die.
It will continue work. In critical cases you should take care, that process will be stopped: Use validation_trouble()!
The validation methods just store messages, if there is a message store available. No messages will be printed out.
The validation methods just give back the value. They even don't process the call parameters of the validation routines.
Be careful! Now you are playing with dynamite! But you are fast. If you explode, just try switch validation on, if you are still alive.
Remove all validation calls from your code and fall back to era before Scalar::Validation.
Be careful! Now you are playing with nitroglycerin! But you cannot be faster.
Having two parameter managements, switch between them by testing $Scalar::Validation::off:
$Scalar::Validation::off
sub create_some_polynom { my ($max_potenz, ) = @_; if ($Scalar::Validation::off) { local ($FSL::Validation::trouble_level) = 0; $max_potenz = par maximum_potenz => -Range => [1,5] => Int => shift; # additional parameters ... p_end \@_; return undef if validation_trouble(); # fire exit, if validation does not die } # --- run sub ------------------------------------------------- my $polynom = ''; map { $polynom .= " + ".int (100*rand())."*x^".($max_potenz-$_); } (0..$max_potenz); return $polynom; };
Now you have only one extra if statement compared to version without checks. But you have duplicate parameter management. So only choose this variant if performance is a real problem for your sub.
Be careful! You are still playing with dynamite! But you are fast. If you explode, just try switch validation on, if you are still alive.
Have a look into Validation.t to see what else is possible
Copyright (c) 2014 by Ralf Peine, Germany. All rights reserved.
This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.6.0 or, at your option, any later version of Perl 5 you may have available.
This library is distributed in the hope that it will be useful, but without any warranty; without even the implied warranty of merchantability or fitness for a particular purpose.
To install Scalar::Validation, copy and paste the appropriate command in to your terminal.
cpanm
cpanm Scalar::Validation
CPAN shell
perl -MCPAN -e shell install Scalar::Validation
For more information on module installation, please visit the detailed CPAN module installation guide.