'\"
'\" Generated from file 'vtype\&.inc' by tcllib/doctools with format 'nroff'
'\" Copyright (c) 2011 Andreas Kupries <andreas_kupries@users\&.sourceforge\&.net>
'\"
.TH "valtype::creditcard::amex" n 1\&.1 tcllib "Validation types"
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.SH NAME
valtype::creditcard::amex \- Validation for AMEX creditcard number
.SH SYNOPSIS
package require \fBTcl 8\&.5 9\fR
.sp
package require \fBsnit 2\fR
.sp
package require \fBvaltype::common\fR
.sp
package require \fBvaltype::luhn\fR
.sp
package require \fBvaltype::creditcard::amex ?1\&.1?\fR
.sp
\fBvaltype::creditcard::amex\fR \fBvalidate\fR \fIvalue\fR
.sp
\fBvaltype::creditcard::amex\fR \fBcheckdigit\fR \fIvalue\fR
.sp
.BE
.SH DESCRIPTION
This package implements a snit validation type for an AMEX creditcard number\&.
.PP
A validation type is an object that can be used to validate Tcl values
of a particular kind\&.  For example, \fBsnit::integer\fR, a validation
type defined by the \fBsnit\fR package is used to validate that a
Tcl value is an integer\&.
.PP
Every validation type has a \fBvalidate\fR 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:
.CS


    valtype::creditcard::amex validate \&.\&.\&.\&. ;# Does nothing
    valtype::creditcard::amex validate \&.\&.\&.\&. ;# Throws an error (bad American Expresss creditcard number)\&.

.CE
.PP
The \fBvalidate\fR method will always return the validated value on
success, and throw the \fB-errorcode\fR INVALID on error, possibly
with additional elements which provide more details about the problem\&.
.SH API
The API provided by this package satisfies the specification
of snit validation types found in the documentation of
\fISnit's Not Incr Tcl\fR\&.
.TP
\fBvaltype::creditcard::amex\fR \fBvalidate\fR \fIvalue\fR
This method validates the \fIvalue\fR and returns it, possibly in a
canonical form, if it passes\&. If the value does not pass the
validation an error is thrown\&.
.TP
\fBvaltype::creditcard::amex\fR \fBcheckdigit\fR \fIvalue\fR
This method computes a check digit for the \fIvalue\fR\&. 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\&.
.PP
.SH "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
\fB-errorcode\fR INVALID to distinguish themselves from package
internal errors\&.
.PP
To provide more detailed information about why the validation
failed the \fB-errorCode\fR goes actually beyond that\&.
First, it will contain a code detailing the type itself\&. Here this is
\fBCREDITCARD AMEX\fR\&. This is then followed by values detailing the
reason for the failure\&. The full set of \fB-errorCode\fRs which can
be thrown by this package are:
.TP
INVALID CREDITCARD AMEX CHARACTER
The input value contained one or more bad characters, i\&.e\&. characters
which must not occur in the input for it to be an AMEX creditcard number\&.
.TP
INVALID CREDITCARD AMEX CHECK-DIGIT
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\&.
.TP
INVALID CREDITCARD AMEX LENGTH
The input value is of the wrong length to be an AMEX creditcard number\&.
.TP
INVALID CREDITCARD AMEX PREFIX
The input value does not start with the magic value(s) required for it
to be an AMEX creditcard number\&.
.PP
.SH "BUGS, IDEAS, FEEDBACK"
This document, and the package it describes, will undoubtedly contain
bugs and other problems\&.
Please report such in the category \fIvaltype\fR of the
\fITcllib Trackers\fR [http://core\&.tcl\&.tk/tcllib/reportlist]\&.
Please also report any ideas for enhancements you may have for either
package and/or documentation\&.
.PP
When proposing code changes, please provide \fIunified diffs\fR,
i\&.e the output of \fBdiff -u\fR\&.
.PP
Note further that \fIattachments\fR are strongly preferred over
inlined patches\&. Attachments can be made by going to the \fBEdit\fR
form of the ticket immediately after its creation, and then using the
left-most button in the secondary navigation bar\&.
.SH KEYWORDS
AMEX, American Express, Checking, Testing, Type checking, Validation, Value checking, bank, card for credit, credit card, finance, isA
.SH CATEGORY
Validation, Type checking
.SH COPYRIGHT
.nf
Copyright (c) 2011 Andreas Kupries <andreas_kupries@users\&.sourceforge\&.net>

.fi
