valtype::isbn(n)

💖 valtype::isbn — the manual page, bestie edition 💖

okay so this is the manual page for valtype::isbn, which lives in section n of the manual (the Tcl command section, iykyk). it's all about checking whether a string is a real ISBN or just vibes. let's get into it 🦋

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✨ NAME ✨

valtype::isbn — validation for ISBN 💅

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🌸 SYNOPSIS 🌸

package require Tcl 8.5 9

package require snit 2

package require valtype::common

package require valtype::isbn ?1.1?

valtype::isbn validate value

valtype::isbn checkdigit value

valtype::isbn 13of value

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🎀 DESCRIPTION 🎀

so this package ships a snit validation type for an ISBN. that's the whole job. she's focused. she's employed. periodt.

now, a validation type is basically an object you can point at Tcl values of some particular kind and be like "is this one of those?" fr fr. for example, snit::integer — a validation type that the snit package defines — exists so you can check that a Tcl value is an integer.

every validation type has a validate method, and that's the one doing the actual checking. the rules are:

• it takes a single argument: the value being validated
• if the value is valid, it does nothing
• if the value is invalid, it throws an error

like so:

valtype::isbn validate .... ;# Does nothing
valtype::isbn validate .... ;# Throws an error (bad ISBN).

and here's the glow-up detail: validate always returns the validated value when it succeeds 🫶, and when it fails it throws with -errorcode INVALID, possibly with extra elements riding along that give you more deets about what went wrong. not me being thorough 💅

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👑 API 👑

the API this package gives you satisfies the spec for snit validation types, which lives in the docs for Snit's Not Incr Tcl. no cap.

• valtype::isbn validate value — validates the value and hands it back, possibly in a canonical form, if it passes. if it does not pass, an error gets thrown. simple as.
• valtype::isbn checkdigit value — computes a check digit for value. before it does any of that, it validates the value — except for the checkdigit itself, she's skipping that part. and if the value fails validation? no check digit for you, an error instead. 🙈
• valtype::isbn 13of value — expects an old-style 10-digit ISBN and returns the canonical modern 13-digit ISBN. validate uses this to canonicalize the input, so that every other part of the system downstream can just assume it's working with modern 13-digit ISBNs. it's giving ✨glow-up transformation✨ honestly.

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💀 ERROR CODES 💀

like the package description said: when these commands hit an input validation failure, the error they throw uses -errorcode INVALID to set itself apart from the package's own internal errors.

but wait, there's more — to give you richer info about why validation flopped, the -errorCode actually goes beyond just that. first it carries a code detailing the type itself. here, that's ISBN. then it's followed by values detailing the reason for the failure. the full set of -errorCodes this package can throw is:

• INVALID ISBN CHARACTER — the input had one or more bad characters, i.e. characters that literally must not show up in the input for it to be an ISBN. not allowed, bestie.
• INVALID ISBN CHECK-DIGIT — the check digit of the input is wrong. this usually means a data-entry oopsie — digits transposed, forgotten, that whole situation. of course, the input could just be an outright fake too. 💀
• INVALID ISBN LENGTH — the input is the wrong length to be an ISBN. she's just not the right size for this.

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🐛 BUGS, IDEAS, FEEDBACK 🐛

this document, and the package it describes, will undoubtedly contain bugs and other problems. it's a manual page, they all do. please report such things in the category valtype of the Tcllib Trackers at http://core.tcl.tk/tcllib/reportlist. and please also report any ideas for enhancements you have for either the package and/or the documentation — we want the thoughts 🫶

if you're proposing code changes, please provide unified diffs, i.e. the output of diff -u.

also note: attachments are strongly preferred over inlined patches. you can attach stuff by going to the Edit form of the ticket immediately after creating it, then using the left-most button in the secondary navigation bar. that's the one. 💅

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⭐ KEYWORDS ⭐

Book Number, Checking, EAN, EAN13, European Article Number, ISBN, International Article Number, International Standard Book Number, Testing, Type checking, Validation, Value checking, isA

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🌈 CATEGORY 🌈

Validation, Type checking

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💜 COPYRIGHT 💜

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

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and that's the whole page, bestie 🎀 this was tcllib version 1.1 of valtype::isbn(n), brought to you with love. go validate something. slay 💅✨