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
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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)