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FFI: Resolve metamethods for constructors, too.

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This commit is contained in:
Mike Pall 2012-06-20 15:15:09 +02:00
parent 126f9906fe
commit 6cee1333ef
2 changed files with 13 additions and 4 deletions
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16
doc/ext_ffi_semantics.html
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@ -590,8 +590,7 @@ ffi.new("struct nested", {x=1,y={2,3}}) --> x = 1, y.a = 2, y.b = 3
<p> <p>
All of the standard Lua operators can be applied to cdata objects or a All of the standard Lua operators can be applied to cdata objects or a
mix of a cdata object and another Lua object. The following list shows mix of a cdata object and another Lua object. The following list shows
the valid combinations. All other combinations currently raise an the pre-defined operations.
error.
</p> </p>
<p> <p>
Reference types are dereferenced <em>before</em> performing each of Reference types are dereferenced <em>before</em> performing each of
@ -600,7 +599,8 @@ C&nbsp;type pointed to by the reference.
</p> </p>
<p> <p>
The pre-defined operations are always tried first before deferring to a The pre-defined operations are always tried first before deferring to a
metamethod for a ctype (if defined). metamethod or index table (if any) for the corresponding ctype. An error
is raised if the metamethod lookup or index table lookup fails.
</p> </p>
<h3 id="cdata_array">Indexing a cdata object</h3> <h3 id="cdata_array">Indexing a cdata object</h3>
@ -625,7 +625,9 @@ field value and <a href="#convert_tolua">converts it to a Lua
object</a>. A write access <a href="#convert_fromlua">converts a Lua object</a>. A write access <a href="#convert_fromlua">converts a Lua
object to the field type</a> and stores the converted value to the object to the field type</a> and stores the converted value to the
field. An error is raised if a write access to a constant field. An error is raised if a write access to a constant
<tt>struct</tt>/<tt>union</tt> or a constant field is attempted.</li> <tt>struct</tt>/<tt>union</tt> or a constant field is attempted.
Scoped enum constants or static constants are treated like a constant
field.</li>
<li><b>Indexing a complex number</b>: a complex number can be indexed <li><b>Indexing a complex number</b>: a complex number can be indexed
either by a cdata number or a Lua number with the values 0 or 1, or by either by a cdata number or a Lua number with the values 0 or 1, or by
@ -644,6 +646,12 @@ assigning to an index of a vector raises an error.</li>
</ul> </ul>
<p> <p>
A ctype object can be indexed with a string key, too. The only
pre-defined operation is reading scoped constants of
<tt>struct</tt>/<tt>union</tt> types. All other accesses defer
to the corresponding metamethods or index tables (if any).
</p>
<p>
Note: since there's (deliberately) no address-of operator, a cdata Note: since there's (deliberately) no address-of operator, a cdata
object holding a value type is effectively immutable after object holding a value type is effectively immutable after
initialization. The JIT compiler benefits from this fact when applying initialization. The JIT compiler benefits from this fact when applying

1
src/lj_cdata.c
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@ -178,6 +178,7 @@ collect_attrib:
if (fct && ctype_isconstval(fct->info)) if (fct && ctype_isconstval(fct->info))
return fct; return fct;
} }
ct = sct; /* Allow resolving metamethods for constructors, too. */
} }
} }
if (ctype_isptr(ct->info)) { /* Automatically perform '->'. */ if (ctype_isptr(ct->info)) { /* Automatically perform '->'. */