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valtype::luhn(n) Validation types valtype::luhn(n) 





NAME


valtype::luhn - Validation for plain number with a LUHN
  checkdigit






SYNOPSIS


package require Tcl 8.5


package require snit 2


package require valtype::common 


package require valtype::luhn ?1?


valtype::luhn validate value


valtype::luhn checkdigit value










DESCRIPTION


This package implements a snit validation type for a plain number
    with a LUHN checkdigit.


A validation type is an object that can be used to validate Tcl
    values of a particular kind. For example, snit::integer, a validation
    type defined by the snit package is used to validate that a Tcl value
    is an integer.


Every validation type has a validate method which is used
    to do the validation. This method must take a single argument, the value to
    be validated; further, it must do nothing if the value is valid, but throw
    an error if the value is invalid:






    valtype::luhn validate .... ;# Does nothing


    valtype::luhn validate .... ;# Throws an error (bad luhn checkdigit).





The validate method will always return the validated value
    on success, and throw the -errorcode INVALID on error, possibly with
    additional elements which provide more details about the problem.






API


The API provided by this package satisfies the specification of
    snit validation types found in the documentation of Snit's Not Incr
    Tcl.



  

  
This method validates the value and returns it, possibly in a
      canonical form, if it passes. If the value does not pass the validation an
      error is thrown.

  

  
This method computes a check digit for the value. Before doing so
      it is validated, except for a checkdigit. If the value does not pass the
      validation no check digit is calculated and an error is thrown
    instead.








ERROR CODES


As said in the package description, the errors thrown by the
    commands of this package in response to input validation failures use the
    -errorcode INVALID to distinguish themselves from package internal
    errors.


To provide more detailed information about why the validation
    failed the -errorCode goes actually beyond that. First, it will
    contain a code detailing the type itself. Here this is LUHN. This is
    then followed by values detailing the reason for the failure. The full set
    of -errorCodes which can be thrown by this package are:



  

  
The input value contained one or more bad characters, i.e. characters
      which must not occur in the input for it to be a plain number with a LUHN
      checkdigit.

  

  
The check digit of the input value is wrong. This usually signals a
      data-entry error, with digits transposed, forgotten, etc. Of course, th
      input may be an outright fake too.








BUGS, IDEAS, FEEDBACK


This document, and the package it describes, will undoubtedly
    contain bugs and other problems. Please report such in the category
    valtype of the Tcllib Trackers
    [http://core.tcl.tk/tcllib/reportlist]. Please also report any ideas for
    enhancements you may have for either package and/or documentation.


When proposing code changes, please provide unified diffs,
    i.e the output of diff -u.


Note further that attachments are strongly preferred over
    inlined patches. Attachments can be made by going to the Edit form of
    the ticket immediately after its creation, and then using the left-most
    button in the secondary navigation bar.






KEYWORDS


Checking, Testing, Type checking, Validation, Value checking, isA,
    luhn






CATEGORY


Validation, Type checking






COPYRIGHT


Copyright (c) 2011 Andreas Kupries <andreas_kupries@users.sourceforge.net>








  

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