84 lines
2.5 KiB
Markdown
84 lines
2.5 KiB
Markdown
ezic
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====
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ezic is a native erlang library for working with timezones. It parses the Olson timezone database files, allowing native erlang timezone lookup and zone conversions without the use of shell commands or a UNIX system.
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See the [tz database](http://www.twinsun.com/tz/tz-link.htm) page for more information about the Olson database.
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Purpose
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-------
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Erlang/OTP didn't have a native timezone library, so I wrote ezic to fill that void.
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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 about it
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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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API
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---
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* `ezic:localtime(TimeZone) -> datetime()`
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* `ezic:utc_to_local(universal_datetime(), TimeZone) -> local_datetime()`
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* `ezic:local_to_utc(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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Example Setup
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-----
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# setup your local environment
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mkdir -p priv/tzdata
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# download the timezone data files
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wget 'ftp://ftp.iana.org/tz/tzdata-latest.tar.gz'
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tar -xvzf tzdata-latest.tar.gz -C priv/tzdata
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# remove a few troublesome files
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cd priv/tzdata
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rm *.sh *.gz *.tab factory Makefile
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# build and run ezic
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cd -
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make all run
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1> application:start(ezic).
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2> ezic:localtime("Australia/Adelaide").
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License
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-------
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This project is in 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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Acknowledgements
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----------------
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The decision to release this into the public domain was inspired by the (anti-) license of the [SQLite project](http://www.sqlite.org/copyright.html).
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