verhoeff(3)



valtype::verhoeff(3tcl)        Validation types        valtype::verhoeff(3tcl)

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NAME
       valtype::verhoeff  - Validation for plain number with a VERHOEFF check-
       digit

SYNOPSIS
       package require Tcl  8.5

       package require snit  2

       package require valtype::common

       package require valtype::verhoeff  ?1?

       valtype::verhoeff validate value

       valtype::verhoeff checkdigit value

______________________________________________________________________________

DESCRIPTION
       This package implements a snit validation type for a plain number  with
       a VERHOEFF 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::verhoeff validate .... ;# Does nothing
                  valtype::verhoeff validate .... ;# Throws an error (bad verhoeff checkdigit).

       The  validate method will always return the validated value on success,
       and throw the -errorcode INVALID on error, possibly with additional el-
       ements 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.

       valtype::verhoeff validate value
              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.

       valtype::verhoeff checkdigit value
              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  er-
              ror 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  -er-
       rorcode 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 VERHOEFF. 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:

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

       INVALID VERHOEFF CHECK-DIGIT
              The  check  digit of the input value is wrong. This usually sig-
              nals 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 out-
       put 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, ver-
       hoeff

CATEGORY
       Validation, Type checking

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

tcllib                                 1               valtype::verhoeff(3tcl)

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