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Get rid of callouts since Markdown doesn't support them

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Eelco Dolstra 2020-07-23 13:58:49 +02:00
parent efff6cf163
commit 13df1faf25
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36
doc/manual/expressions/language-constructs.xml
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@ -278,7 +278,9 @@ evaluate to a Boolean value. If it evaluates to
<literal>true</literal>, <replaceable>e2</replaceable> is returned;
otherwise expression evaluation is aborted and a backtrace is printed.</para>
<example xml:id='ex-subversion-nix'><title>Nix expression for Subversion</title>
<para>Here is a Nix expression for the Subversion package that shows
how assertions can be used:.</para>
<programlisting>
{ localServer ? false
, httpServer ? false
@ -290,9 +292,9 @@ otherwise expression evaluation is aborted and a backtrace is printed.</para>
, openssl ? null, httpd ? null, db4 ? null, expat, swig ? null, j2sdk ? null
}:
assert localServer -> db4 != null; <co xml:id='ex-subversion-nix-co-1' />
assert httpServer -> httpd != null &amp;&amp; httpd.expat == expat; <co xml:id='ex-subversion-nix-co-2' />
assert sslSupport -> openssl != null &amp;&amp; (httpServer -> httpd.openssl == openssl); <co xml:id='ex-subversion-nix-co-3' />
assert localServer -> db4 != null; ①
assert httpServer -> httpd != null &amp;&amp; httpd.expat == expat; ②
assert sslSupport -> openssl != null &amp;&amp; (httpServer -> httpd.openssl == openssl); ③
assert pythonBindings -> swig != null &amp;&amp; swig.pythonSupport;
assert javaSwigBindings -> swig != null &amp;&amp; swig.javaSupport;
assert javahlBindings -> j2sdk != null;
@ -300,26 +302,24 @@ assert javahlBindings -> j2sdk != null;
stdenv.mkDerivation {
name = "subversion-1.1.1";
...
openssl = if sslSupport then openssl else null; <co xml:id='ex-subversion-nix-co-4' />
openssl = if sslSupport then openssl else null; ④
...
}</programlisting>
</example>
<para><xref linkend='ex-subversion-nix' /> show how assertions are
used in the Nix expression for Subversion.</para>
<para>The points of interest are:</para>
<calloutlist>
<orderedlist>
<callout arearefs='ex-subversion-nix-co-1'>
<listitem>
<para>This assertion states that if Subversion is to have support
for local repositories, then Berkeley DB is needed. So if the
Subversion function is called with the
<varname>localServer</varname> argument set to
<literal>true</literal> but the <varname>db4</varname> argument
set to <literal>null</literal>, then the evaluation fails.</para>
</callout>
</listitem>
<callout arearefs='ex-subversion-nix-co-2'>
<listitem>
<para>This is a more subtle condition: if Subversion is built with
Apache (<literal>httpServer</literal>) support, then the Expat
library (an XML library) used by Subversion should be same as the
@ -327,27 +327,27 @@ used in the Nix expression for Subversion.</para>
Subversion code ends up being linked with Apache code, and if the
Expat libraries do not match, a build- or runtime link error or
incompatibility might occur.</para>
</callout>
</listitem>
<callout arearefs='ex-subversion-nix-co-3'>
<listitem>
<para>This assertion says that in order for Subversion to have SSL
support (so that it can access <literal>https</literal> URLs), an
OpenSSL library must be passed. Additionally, it says that
<emphasis>if</emphasis> Apache support is enabled, then Apache's
OpenSSL should match Subversion's. (Note that if Apache support
is not enabled, we don't care about Apache's OpenSSL.)</para>
</callout>
</listitem>
<callout arearefs='ex-subversion-nix-co-4'>
<listitem>
<para>The conditional here is not really related to assertions,
but is worth pointing out: it ensures that if SSL support is
disabled, then the Subversion derivation is not dependent on
OpenSSL, even if a non-<literal>null</literal> value was passed.
This prevents an unnecessary rebuild of Subversion if OpenSSL
changes.</para>
</callout>
</listitem>
</calloutlist>
</orderedlist>
</simplesect>