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* Remove references to __XXX primops.

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This commit is contained in:
Eelco Dolstra 2009-04-14 13:03:27 +00:00
parent 8b2a01a8c2
commit 435a93b5d8
2 changed files with 4 additions and 14 deletions
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14
doc/manual/builtins.xml
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@ -77,18 +77,8 @@ attrValues = attrs: map (name: builtins.getAttr name attrs) (builtins.attrNames
if builtins ? getEnv then builtins.getEnv "PATH" else ""</programlisting>
This allows a Nix expression to fall back gracefully on older Nix
installations that don’t have the desired built-in function.
However, in that case you should not write
<programlisting>
if builtins ? getEnv then __getEnv "PATH" else ""</programlisting>
This Nix expression will trigger an “undefined variable” error on
older Nix versions since <function>__getEnv</function> doesn’t
exist. <literal>builtins.getEnv</literal>, on the other hand, is
safe since <literal>builtins</literal> always exists and attribute
selection is lazy, so it’s only performed if the test
succeeds.</para></listitem>
installations that don’t have the desired built-in
function.</para></listitem>
</varlistentry>