1.8 KiB
| date | description | tags | slug | title | |||
|---|---|---|---|---|---|---|---|
| 2014-04-18T20:25:00Z | Simple workaround for supporting deprecated types and warnings_as_errors. |
|
erlang-17-0-supporting-deprecated-types-without-removing-warnings_as_errors | Erlang 17.0: Supporting Deprecated Types Without Removing warnings_as_errors |
Erlang 17.0 deprecated some pre-defined types like dict() and gb_tree() in favor of dict:dict() and gb_tree:tree(). The workaround they suggest (nowarn_deprecated_type) works in 17.0, but would break once the deprecated types are removed.
Not using nowarn_deprecated_type means that you can't use warnings_as_errors, because it would make deprecation warnings an error.
A rather nice solution to this issue an option that rebar takes: platform_define.
It is also possible to specify platform specific options by specifying a pair or a triplet where the first string is a regex that is checked against the string
OtpRelease ++ "-" ++ SysArch ++ "-" ++ Words.
where
OtpRelease = erlang:system_info(otp_release).
SysArch = erlang:system_info(system_architecture).
Words = integer_to_list(8 * erlang:system_info({wordsize, external})).
This allows us to set a namespaced_types option on 17.0+ only.
{{< highlight erlang >}} {erl_opts, [ {platform_define, "^[0-9]+", namespaced_types}, debug_info, warnings_as_errors ]}. {{< / highlight >}}
In your source files you can then check if the option is set and define an (internal) type accordingly.
{{< highlight erlang "linenos=table" >}} -ifdef(namespaced_types). -type xxx_dict() :: dict:dict(). -else. -type xxx_dict() :: dict(). -endif. {{< / highlight >}}
I learned about this trick by looking at how meck handles Erlang 17.0 support.