diff options
Diffstat (limited to 'development/errorhandling.html')
| -rw-r--r-- | development/errorhandling.html | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/development/errorhandling.html b/development/errorhandling.html new file mode 100644 index 00000000..1d79eda7 --- /dev/null +++ b/development/errorhandling.html @@ -0,0 +1,193 @@ +<!DOCTYPE html> +<html class="writer-html5" lang="en" > +<head> + <meta charset="utf-8" /><meta name="generator" content="Docutils 0.17.1: http://docutils.sourceforge.net/" /> + + <meta name="viewport" content="width=device-width, initial-scale=1.0" /> + <title>Error handling — PROJ 9.0.0 documentation</title> + <link rel="stylesheet" href="../_static/pygments.css" type="text/css" /> + <link rel="stylesheet" href="../_static/css/theme.css" type="text/css" /> + <link rel="shortcut icon" href="../_static/favicon.png"/> + <link rel="canonical" href="https://proj.orgdevelopment/errorhandling.html"/> + <!--[if lt IE 9]> + <script src="../_static/js/html5shiv.min.js"></script> + <![endif]--> + + <script data-url_root="../" id="documentation_options" src="../_static/documentation_options.js"></script> + <script src="../_static/jquery.js"></script> + <script src="../_static/underscore.js"></script> + <script src="../_static/doctools.js"></script> + <script src="../_static/js/theme.js"></script> + <link rel="author" title="About these documents" href="../about.html" /> + <link rel="index" title="Index" href="../genindex.html" /> + <link rel="search" title="Search" href="../search.html" /> + <link rel="next" title="Reference" href="reference/index.html" /> + <link rel="prev" title="Transformations" href="transformations.html" /> +</head> + +<body class="wy-body-for-nav"> + <div class="wy-grid-for-nav"> + <nav data-toggle="wy-nav-shift" class="wy-nav-side"> + <div class="wy-side-scroll"> + <div class="wy-side-nav-search" style="background: #353130" > + <a href="../index.html"> + <img src="../_static/logo.png" class="logo" alt="Logo"/> + </a> + <div class="version"> + 9.0.0 + </div> +<div role="search"> + <form id="rtd-search-form" class="wy-form" action="../search.html" method="get"> + <input type="text" name="q" placeholder="Search docs" /> + <input type="hidden" name="check_keywords" value="yes" /> + <input type="hidden" name="area" value="default" /> + </form> +</div> + </div><div class="wy-menu wy-menu-vertical" data-spy="affix" role="navigation" aria-label="Navigation menu"> + <ul class="current"> +<li class="toctree-l1"><a class="reference internal" href="../about.html">About</a></li> +<li class="toctree-l1"><a class="reference internal" href="../news.html">News</a></li> +<li class="toctree-l1"><a class="reference internal" href="../download.html">Download</a></li> +<li class="toctree-l1"><a class="reference internal" href="../install.html">Installation</a></li> +<li class="toctree-l1"><a class="reference internal" href="../usage/index.html">Using PROJ</a></li> +<li class="toctree-l1"><a class="reference internal" href="../apps/index.html">Applications</a></li> +<li class="toctree-l1"><a class="reference internal" href="../operations/index.html">Coordinate operations</a></li> +<li class="toctree-l1"><a class="reference internal" href="../resource_files.html">Resource files</a></li> +<li class="toctree-l1"><a class="reference internal" href="../geodesic.html">Geodesic calculations</a></li> +<li class="toctree-l1 current"><a class="reference internal" href="index.html">Development</a><ul class="current"> +<li class="toctree-l2"><a class="reference internal" href="quickstart.html">Quick start</a></li> +<li class="toctree-l2"><a class="reference internal" href="transformations.html">Transformations</a></li> +<li class="toctree-l2 current"><a class="current reference internal" href="#">Error handling</a></li> +<li class="toctree-l2"><a class="reference internal" href="reference/index.html">Reference</a></li> +<li class="toctree-l2"><a class="reference internal" href="cmake.html">Using PROJ in CMake projects</a></li> +<li class="toctree-l2"><a class="reference internal" href="bindings.html">Language bindings</a></li> +<li class="toctree-l2"><a class="reference internal" href="migration.html">Version 4 to 6 API Migration</a></li> +<li class="toctree-l2"><a class="reference internal" href="migration.html#version-4-to-5-api-migration">Version 4 to 5 API Migration</a></li> +</ul> +</li> +<li class="toctree-l1"><a class="reference internal" href="../specifications/index.html">Specifications</a></li> +<li class="toctree-l1"><a class="reference internal" href="../community/index.html">Community</a></li> +<li class="toctree-l1"><a class="reference internal" href="../faq.html">FAQ</a></li> +<li class="toctree-l1"><a class="reference internal" href="../glossary.html">Glossary</a></li> +<li class="toctree-l1"><a class="reference internal" href="../zreferences.html">References</a></li> +</ul> + + </div> + </div> + </nav> + + <section data-toggle="wy-nav-shift" class="wy-nav-content-wrap"><nav class="wy-nav-top" aria-label="Mobile navigation menu" style="background: #353130" > + <i data-toggle="wy-nav-top" class="fa fa-bars"></i> + <a href="../index.html">PROJ</a> + </nav> + + <div class="wy-nav-content"> + <div class="rst-content"> + <div role="navigation" aria-label="Page navigation"> + <ul class="wy-breadcrumbs"> + <li><a href="../index.html" class="icon icon-home"></a> »</li> + <li><a href="index.html">Development</a> »</li> + <li>Error handling</li> + <li class="wy-breadcrumbs-aside"> + <a href="https://github.com/OSGeo/PROJ/edit/8.2/docs/source/development/errorhandling.rst" class="fa fa-github"> Edit on GitHub</a> + </li> + </ul><div class="rst-breadcrumbs-buttons" role="navigation" aria-label="Sequential page navigation"> + <a href="transformations.html" class="btn btn-neutral float-left" title="Transformations" accesskey="p"><span class="fa fa-arrow-circle-left" aria-hidden="true"></span> Previous</a> + <a href="reference/index.html" class="btn btn-neutral float-right" title="Reference" accesskey="n">Next <span class="fa fa-arrow-circle-right" aria-hidden="true"></span></a> + </div> + <hr/> +</div> + <div role="main" class="document" itemscope="itemscope" itemtype="http://schema.org/Article"> + <div itemprop="articleBody"> + + <section id="error-handling"> +<span id="errorhandling"></span><h1>Error handling<a class="headerlink" href="#error-handling" title="Permalink to this headline">¶</a></h1> +<p>PROJ maintains an internal error state, which is local to a +<a class="reference internal" href="reference/datatypes.html#c.PJ_CONTEXT" title="PJ_CONTEXT"><code class="xref c c-type docutils literal notranslate"><span class="pre">PJ_CONTEXT</span></code></a> thread context.</p> +<p>See <a class="reference internal" href="quickstart.html"><span class="doc">Quick start</span></a> for more information about how to create and use a thread +context object.</p> +<p>If you receive an abnormal return from a PROJ API function (e.g. a NULL +pointer) you may wish to discover more information about the error.</p> +<p>In this case you can make a call to <a class="reference internal" href="reference/functions.html#c.proj_context_errno" title="proj_context_errno"><code class="xref c c-func docutils literal notranslate"><span class="pre">proj_context_errno()</span></code></a>, passing in +your thread context. This will return an integer error code.</p> +<p>If the error code is zero, the last PROJ operation was deemed successful and no +error has been detected.</p> +<p>If the error code is non-zero, an error has been detected. You can pass your +thread context together with this error code to +<a class="reference internal" href="reference/functions.html#c.proj_context_errno_string" title="proj_context_errno_string"><code class="xref c c-func docutils literal notranslate"><span class="pre">proj_context_errno_string()</span></code></a> to retrieve a string describing the error +condition.</p> +<p>A basic example showing how a C program might catch and report errors follows:</p> +<div class="literal-block-wrapper docutils container" id="id1"> +<div class="code-block-caption"><span class="caption-text">errorhandling.c</span><a class="headerlink" href="#id1" title="Permalink to this code">¶</a></div> +<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="linenos"> 1</span><span class="w"> </span><span class="cp">#include</span><span class="w"> </span><span class="cpf"><stdio.h></span><span class="cp"></span> +<span class="linenos"> 2</span><span class="w"> </span><span class="cp">#include</span><span class="w"> </span><span class="cpf"><proj.h></span><span class="cp"></span> +<span class="linenos"> 3</span> +<span class="linenos"> 4</span><span class="w"> </span><span class="kt">int</span><span class="w"> </span><span class="nf">main</span><span class="w"> </span><span class="p">(</span><span class="kt">void</span><span class="p">)</span><span class="w"> </span><span class="p">{</span><span class="w"></span> +<span class="linenos"> 5</span><span class="w"> </span><span class="n">PJ_CONTEXT</span><span class="w"> </span><span class="o">*</span><span class="n">c</span><span class="p">;</span><span class="w"></span> +<span class="linenos"> 6</span><span class="w"> </span><span class="n">PJ</span><span class="w"> </span><span class="o">*</span><span class="n">p</span><span class="p">;</span><span class="w"></span> +<span class="linenos"> 7</span><span class="w"> </span><span class="kt">int</span><span class="w"> </span><span class="n">errno</span><span class="p">;</span><span class="w"></span> +<span class="linenos"> 8</span><span class="w"> </span><span class="k">const</span><span class="w"> </span><span class="kt">char</span><span class="w"> </span><span class="o">*</span><span class="n">errstr</span><span class="p">;</span><span class="w"></span> +<span class="linenos"> 9</span> +<span class="linenos">10</span><span class="w"> </span><span class="n">c</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">proj_context_create</span><span class="p">();</span><span class="w"></span> +<span class="linenos">11</span><span class="w"> </span><span class="n">p</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">proj_create_crs_to_crs</span><span class="p">(</span><span class="n">c</span><span class="p">,</span><span class="w"> </span><span class="s">"EPSG:4326"</span><span class="p">,</span><span class="w"> </span><span class="s">"EPSG:3857"</span><span class="p">,</span><span class="w"> </span><span class="nb">NULL</span><span class="p">);</span><span class="w"></span> +<span class="linenos">12</span> +<span class="linenos">13</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">p</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">0</span><span class="p">)</span><span class="w"> </span><span class="p">{</span><span class="w"></span> +<span class="linenos">14</span><span class="w"> </span><span class="cm">/* Something is wrong, let's try to get details ... */</span><span class="w"></span> +<span class="linenos">15</span><span class="w"> </span><span class="n">errno</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">proj_context_errno</span><span class="p">(</span><span class="n">c</span><span class="p">);</span><span class="w"></span> +<span class="linenos">16</span><span class="w"> </span><span class="k">if</span><span class="w"> </span><span class="p">(</span><span class="n">errno</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="mi">0</span><span class="p">)</span><span class="w"> </span><span class="p">{</span><span class="w"></span> +<span class="linenos">17</span><span class="w"> </span><span class="cm">/* This should be impossible. */</span><span class="w"></span> +<span class="linenos">18</span><span class="w"> </span><span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span><span class="w"> </span><span class="s">"Failed to create transformation, reason unknown.</span><span class="se">\n</span><span class="s">"</span><span class="p">);</span><span class="w"></span> +<span class="linenos">19</span><span class="w"> </span><span class="p">}</span><span class="w"> </span><span class="k">else</span><span class="w"> </span><span class="p">{</span><span class="w"></span> +<span class="linenos">20</span><span class="w"> </span><span class="n">errstr</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">proj_context_errno_string</span><span class="p">(</span><span class="n">c</span><span class="p">,</span><span class="w"> </span><span class="n">errno</span><span class="p">);</span><span class="w"></span> +<span class="linenos">21</span><span class="w"> </span><span class="n">fprintf</span><span class="p">(</span><span class="n">stderr</span><span class="p">,</span><span class="w"> </span><span class="s">"Failed to create transformation: %s.</span><span class="se">\n</span><span class="s">"</span><span class="p">,</span><span class="w"> </span><span class="n">errstr</span><span class="p">);</span><span class="w"></span> +<span class="linenos">22</span><span class="w"> </span><span class="p">}</span><span class="w"></span> +<span class="linenos">23</span><span class="w"> </span><span class="n">proj_context_destroy</span><span class="p">(</span><span class="n">c</span><span class="p">);</span><span class="w"></span> +<span class="linenos">24</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="mi">1</span><span class="p">;</span><span class="w"></span> +<span class="linenos">25</span><span class="w"> </span><span class="p">}</span><span class="w"></span> +<span class="linenos">26</span> +<span class="linenos">27</span><span class="w"> </span><span class="cm">/* transformation object is valid, do work ... */</span><span class="w"></span> +<span class="linenos">28</span> +<span class="linenos">29</span><span class="w"> </span><span class="n">proj_destroy</span><span class="p">(</span><span class="n">p</span><span class="p">);</span><span class="w"></span> +<span class="linenos">30</span><span class="w"> </span><span class="n">proj_context_destroy</span><span class="p">(</span><span class="n">c</span><span class="p">);</span><span class="w"></span> +<span class="linenos">31</span> +<span class="linenos">32</span><span class="w"> </span><span class="k">return</span><span class="w"> </span><span class="mi">0</span><span class="p">;</span><span class="w"></span> +<span class="linenos">33</span><span class="w"> </span><span class="p">}</span><span class="w"></span> +</pre></div> +</div> +</div> +</section> + + + </div> + </div> + <footer><div class="rst-footer-buttons" role="navigation" aria-label="Footer"> + <a href="transformations.html" class="btn btn-neutral float-left" title="Transformations" accesskey="p" rel="prev"><span class="fa fa-arrow-circle-left" aria-hidden="true"></span> Previous</a> + <a href="reference/index.html" class="btn btn-neutral float-right" title="Reference" accesskey="n" rel="next">Next <span class="fa fa-arrow-circle-right" aria-hidden="true"></span></a> + </div> + + <hr/> + + <div role="contentinfo"> + <p>© Copyright 1983-2022. + <span class="lastupdated">Last updated on 22 Mar 2022. + </span></p> + </div> + + Built with <a href="https://www.sphinx-doc.org/">Sphinx</a> using a + <a href="https://github.com/readthedocs/sphinx_rtd_theme">theme</a> + provided by <a href="https://readthedocs.org">Read the Docs</a>. + + +</footer> + </div> + </div> + </section> + </div> + <script> + jQuery(function () { + SphinxRtdTheme.Navigation.enable(true); + }); + </script> + +</body> +</html>
\ No newline at end of file |