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Deprecated types with erlang.mk + Archives

This commit is contained in:
Daniel Kempkens 2014-12-24 13:26:03 +01:00
parent 31e903b058
commit 360eebb61a
4 changed files with 60 additions and 2 deletions

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At work, we needed a simple way to buffer a polyline in order to search for stuff along the route from A to B. I'll explain how we used Google's Maps API and [JSTS](https://github.com/bjornharrtell/jsts) in order to achieve this easily.
The first thing we had to do, was to "transform" each element in the `overview_path` (which the `DirectionsService` returns) to GeoJSON, because that's what JSTS understands.
The first thing we had to do was to "transform" each element in the `overview_path` (which the `DirectionsService` returns) to GeoJSON, because that's what JSTS understands.
{% highlight javascript linenos %}
var overviewPath = response.routes[0].overview_path,

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---
layout: post
title: Supporting Deprecated Types with erlang.mk
description: "Simple workaround for supporting deprecated types and warnings_as_errors with erlang.mk."
date: 2014-12-24 13:25:00 CET
category: posts
tags: [erlang, programming, english]
comments: true
---
In April I wrote about how I use the `platform_define` feature of [rebar](https://github.com/rebar/rebar) to make deprecated types work without removing `warnings_as_errors`. I have switched to [erlang.mk](https://github.com/ninenines/erlang.mk) since then, but needed a similar feature for [one of my libraries](https://github.com/nifoc/noesis).
Since erlang.mk only uses [make](http://en.wikipedia.org/wiki/Make_(software)), adding support for a `platform_define`-like feature is very straightforward.
{% highlight makefile %}
otp_release = $(shell erl -noshell -eval 'io:format("~s", [erlang:system_info(otp_release)]), init:stop()')
otp_17plus = $(shell echo $(otp_release) | grep -q -E "^[[:digit:]]+$$" ; echo $$?)
{% endhighlight %}
The first variable (`otp_release`) will contain the OTP version (e.g. `17`). The second variable (`otp_17plus`) will be either `0` or `1`, depending on wether or not `otp_release` matches a regular expression. The regular expression checks if `otp_release` is just a number (e.g. `17`) or not (e.g. `R16B03-1`).
That's enough to conditionally add options to `erlc`.
{% highlight makefile %}
ifeq ($(otp_17plus),0)
ERLC_OPTS += -Dnamespaced_types=1
TEST_ERLC_OPTS += -Dnamespaced_types=1
endif
{% endhighlight %}
This will define `namespaced_types` only on Erlang 17+, allowing you to use the same `ifdef`-switch from April.
{% highlight erlang linenos %}
-ifdef(namespaced_types).
-type xxx_dict() :: dict:dict().
-else.
-type xxx_dict() :: dict().
-endif.
{% endhighlight %}

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archives/posts.html Normal file
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---
layout: page
title: Post Archive
---
{% for post in site.posts %}
{% capture month %}{{ post.date | date: '%m%Y' }}{% endcapture %}
{% capture nmonth %}{{ post.next.date | date: '%m%Y' }}{% endcapture %}
{% if month != nmonth %}
{% if forloop.index != 1 %}
</ul>
{% endif %}
<h3>{{ post.date | date: '%B %Y' }}</h3>
<ul>
{% endif %}
<li><a href="{{ post.url }}">{{ post.title }}</a></li>
{% endfor %}

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---
layout: page
permalink: /tags/
title: Tag Archive
---