source: project/wiki/eggref/4/srfi-29 @ 15723

[[tags: egg]]

== srfi-29

A Chicken implementation of
[[http://srfi.schemers.org/srfi-29/srfi-29.html|SRFI 29]].

The addition of the escape code {{~[n]@*}} to the SRFI 28 {{format}} is '''not''' part of
this extention.

[[toc:]]


== Documentation

=== Parameters

==== current-language

<parameter>(current-language [LANGUAGE])</parameter>

Gets or sets the {{LANGUAGE}} symbol.

==== current-country

<parameter>(current-country [COUNTRY])</parameter>

Gets or sets the {{COUNTRY}} symbol.

==== current-locale-details

<parameter>(current-locale-details [LOCALE-DETAILS])</parameter>

Gets or sets the {{LOCALE-DETAILS}} list.

==== current-locale-format-function

<parameter>(current-locale-format-function [FORMAT-PROCEDURE])

Gets or sets the {{FORMAT-PROCEDURE}}.

This procedure must at least have the signature of a SRFI 28 {{format}}
procedure. The default is the Chicken {{format}} procedure.

==== reset-locale-parameters

<procedure>(reset-locale-parameters)</procedure>

When the {{current-locale}} is changed, (see the [[eggs/locale.html|locale egg]]),
the {{current-*}} parameters need not be set individually. This will
update those parameters to the values in the new locale. (Reset as in set
anew.)


=== Bundle Operations

A {{BUNDLE-SPECIFIER}} is a list of symbols of the form
{{(PACKAGE-NAME [LANGUAGE] [COUNTRY] [DETAILS...])}}.

A {{BUNDLE-ALIST}} is a list composed of pairs of the form {{(TEMPLATE-NAME . TEMPLATE-VALUE)}}.

A {{TEMPLATE-NAME}} is something suitable as a key, such as a {{symbol}} or
{{string}}, but maybe any object.

A {{TEMPLATE-VALUE}} maybe any object.

Note that while a {{TEMPLATE-NAME}} and {{TEMPLATE-VALUE}} can be any object
they really should belong to the set of objects with a unique print-form.

==== declare-bundle!

<procedure>(declare-bundle! BUNDLE-SPECIFIER BUNDLE-ALIST)</procedure>

Creates a bundle.

==== undeclare-bundle!

<procedure>(undeclare-bundle! BUNDLE-SPECIFIER)</procedure>

Removes the bundle specified by {{BUNDLE-SPECIFIER}} from the active bundles.


=== Bundle Database Operations

While SRFI 29 does not specify how bundles are stored. This extension uses the
filesystem is used for the bundle database.

Bundles are stored in the system bundle directory, {{(repository-path)
"srfi-29-bundles"}}, unless an {{ALTERNATE}} directory is specified. Within a
bundle directory the structure is {{[LANGUAGE [COUNTRY [SCRIPT [CODESET
[MODIFIER]]]]] PACKAGE-NAME}}.

==== store-bundle!

<procedure>(store-bundle! BUNDLE-SPECIFIER [ALTERNATE])</procedure>

Stores the bundle using the {{write}} procedure.

==== load-bundle!

<procedure>(load-bundle! BUNDLE-SPECIFIER [ALTERNATE])</procedure>

Loads the bundle using the {{read}} procedure.

==== load-best-available-bundle!

<procedure>(load-best-available-bundle! BUNDLE-SPECIFIER [ALTERNATE])</procedure>

Attempts {{(load-bundle! BUNDLE-SPECIFIER [ALTERNATE])}}, from most
to least specific.

See {{most-specific-bundle-specifier}}.

==== remove-bundle!

<procedure>(remove-bundle! BUNDLE-SPECIFIER [ALTERNATE])</procedure>

Removes the bundle specified by {{BUNDLE-SPECIFIER}} from the active bundles,
and from the filesystem.

Will not remove the locale directory hierarchy created by
{{(store-bundle!...)}}.

==== remove-bundle-directory!

<procedure>(remove-bundle-directory! BUNDLE-SPECIFIER [ALTERNATE])</procedure>

Removes the bundle directory hierarchy created by {{(store-bundle!...)}}. Will
only remove empty directories. Returns {{#t}} if operation succeeded, {{#f}}
when a non-empty directory encountered.

Does not remove the bundle, if any, from the active bundles. A filesystem only
operation.

This procedure should be used with caution.

==== declared-bundle-specifiers

<procedure>(declared-bundle-specifiers) => LIST</procedure>

Returns a list of all the declared {{BUNDLE-SPECIFIER}}s.

==== declared-bundle-templates

<procedure>(declared-bundle-templates BUNDLE-SPECIFIER) => LIST</procedure>

Returns an association-list of all the templates for the {{BUNDLE-SPECIFIER}}.

==== most-specific-bundle-specifier

<procedure>(most-specific-bundle-specifier PACKAGE-NAME) => BUNDLE-SPECIFIER</procedure>

Returns the most specific bundle specifier for the current locale.

The current locale is composed of the {{(current-language)}},
{{(current-country)}}, and {{(current-locale-details)}}.

Note that the {{most-specific-bundle-specifier}} may not be a declared bundle.


=== Bundle Template Operations

These routines will use the most specific declared bundle for the package
{{PACKAGE-NAME}} in the current locale.

==== localized-template

<procedure>(localized-template PACKAGE-NAME TEMPLATE-NAME [NOT-FOUND #f])</procedure>

Returns the object for the {{TEMPLATE-NAME}} in {{PACKAGE-NAME}}, when found,
otherwise the {{NOT-FOUND}} value.

==== localized-template/default

<procedure>(localized-template/default PACKAGE-NAME TEMPLATE-NAME [NOT-FOUND TEMPLATE-NAME])</procedure>

Returns {{(localized-template PACKAGE-NAME TEMPLATE-NAME NOT-FOUND)}}.

Somewhat like the Posix 'gettext' routine.

==== localized-format

<procedure>(localized-format PACKAGE-NAME TEMPLATE-NAME ARG0...) => STRING</procedure>

Returns the formatted string using the {{(current-locale-format-function)}} and
the format string {{(localized-template PACKAGE-NAME TEMPLATE-NAME)}} on the
arguments {{ARG0...}}.

When a localized-template is not found and the {{TEMPLATE-NAME}} is a
{{string}} then it is used a the format-string.

A representation is always displayed, even when no template is found. Just not
a localized one.

==== localized-template-set!

<procedure>(localized-template-set! PACKAGE-NAME TEMPLATE-NAME VALUE)</procedure>

Creates or updates the {{VALUE}} for the {{TEMPLATE-NAME}} in {{PACKAGE-NAME}}
and returns {{#t}}, when the package exists. Otherwise returns {{#f}}.

This can be used to extend the meaning of a package template at runtime. For
example: caching the actual closure for a named procedure.

==== localized-templates

<procedure>(localized-templates PACKAGE-NAME) => LIST</procedure>

Returns an association-list of all the templates for the {{PACKAGE-NAME}}.


=== Exceptions

* An unknown bundle-specification raises the composite-condition {{(exn srfi-29 undefined)}}.

* Type exceptions {{(exn type)}} are possible.


== Usage

<enscript language=scheme>
(require-extension srfi-29)
</enscript>


== Examples


== Notes

* Possible race condition creating a bundle file or directory.

* The locale symbols must have a lowercase printname! As such they do not truly
reflect ISO 639-1/2 & ISO 3166-1 standard names. This is a SRFI 29 restriction.

* {{(current-locale-details)}} is ill-defined by SRFI 29. Which symbol means
what? This implementation defines locale details as a 3 element list {{(SCRIPT
CODESET MODIFIER)}} where the elements are symbols or {{#f}}.

* The SRFI 29 document uses the term "country" for what the locale extension
knows as "region".


== Requirements

[[lookup-table|lookup-table]]
[[miscmacros|miscmacros]]
[[locale|locale]]
[[check-errors|check-errors]]


== Bugs and Limitations


== Author

[[kon lovett]]


== Version history

; 2.0.0 : Intitial Chicken 4 release. Added introspection routines. Removed {{PORT}} parameter for {{localized-format}}.


== License

Copyright (C) 2009 Kon Lovett.  All rights reserved.

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the Software), to deal in the
Software without restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the
Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED ASIS, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.