84 lines
2.4 KiB
Markdown
84 lines
2.4 KiB
Markdown
ezic
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====
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ezic is a set of erlang utilities for the Olsen timezone database files. See the [tz database](http://www.twinsun.com/tz/tz-link.htm) page for more information.
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License
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-------
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I have dedicated this work to the [public domain](http://en.wikipedia.org/wiki/Public_Domain). Anyone is free to copy, modify, publish, use, compile, sell, or distribute the original code, either in source code form or as a compiled binary, for any purpose, commercial or non-commercial, and by any means.
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Contributed Code
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----------------
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To maintain ezic's status as a public domain work, all contributions must also be dedicated to the public domain.
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Status
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------
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2010.11.04
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* ezic is "apparently functional". It has been tested very lightly, a bit by unit tests, but mostly by inspection. It's probably not fit for production use.
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API
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---
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* `ezic:localtime(TimeZone) -> datetime()`
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* `ezic:utc_to_time(universal_datetime(), TimeZone) -> local_datetime()`
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* `ezic:utc_from_time(local_datetime(), TimeZone) -> universal_datetime()`
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* `ezic:zone_convert(from_datetime(), TimeZoneFrom, TimeZoneTo) -> to_datetime()`
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Admin API
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-------
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* `ezic:load("/path/to/tzdata") -> ok`
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Setup
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-----
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# download the timezone data files
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wget 'ftp://elsie.nci.nih.gov/pub/tzdata*.tar.gz'
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tar -xvzf tzdata*.tar.gz -C /path/to/tzdata
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# remove a few troublesome files
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cd /path/to/tzdata
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rm *.sh *.tab factory
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# build and run ezic
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make all run
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1> ezic:load("/path/to/tzdata").
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2> ezic:localtime("Australia/Adelaide").
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Purpose
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-------
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Erlang/OTP doesn't have a timezone library, so I decided to write one.
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The [recommended way](http://www.erlang.org/pipermail/erlang-questions/2006-December/024291.html) of handling timezones in erlang involves setting the system environment variable `TZ` to the desired timezone, then calling erlang time functions. As far as I can tell, this technique has a few key issues:
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* it only works on *nix systems,
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* it depends on your system's timezone data (preventing custom timezone hackery), and
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* you can create race conditions if you aren't careful
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ezic doesn't have these problems. ezic is, however, a young project with who-knows-how-many problems of its own ;)
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Acknowledgements
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----------------
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I was inspired by the (anti-) license of the [SQLite project](http://www.sqlite.org/copyright.html) in my decision to release this into the public domain.
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