Adding an overload for the assignment operator in lua for luabind classes

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Hi,

Lua does not allow the assignment operator to be overloaded and has no meta
function for it. I have got around this by using the proxy pattern and the
__index/__newindex meta methods.

Now I have begun using classes defined via luabind's object oriented system
thats exposed to Lua.

I am wondering if the C++ code for Luabind can be changed to allow the
assignment operator to be overloaded without changing the code for the Lua
interpretor itself.

Perhaps such a overload would call into a new meta-method name thats not
used by Lua such as '__assign()'

This would not conflict with any meta method that Lua already uses and
would apply only to instances of luabind classes.

I am guessing that the luabind::adl::object class needs to be changed, or
perhaps index_proxy. But I am not sufficiently familiar with how luabind
forwards calls to existing Lua meta-methods, to its objects.

Has anyone explored the C++ code in luabind that supports operator
overloading in Lua?

Edit: I see some attempts to add a new operator here:
https://github.com/decimad/luabind-deboostified/commit/55b1bd9217205253b41ab7d4746637ee5b0d276f

If I try the above with the assignment operator though, I do no see it
getting called in Lua. Are there any other changes needed in C++ for this?

http://stackoverflow.com/questions/33141507/adding-an-overload-for-the-assignment-operator-in-lua-for-luabind-classes

Thanks,

Abhi

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<div dir=3D"ltr"><p style=3D"margin:0px 0px 1em;padding:0px;border:0px;font=
-size:15px;clear:both;font-family:&#39;Helvetica Neue&#39;,Helvetica,Arial,=
sans-serif;line-height:15.6px">Hi,</p><p style=3D"margin:0px 0px 1em;paddin=
g:0px;border:0px;font-size:15px;clear:both;font-family:&#39;Helvetica Neue&=
#39;,Helvetica,Arial,sans-serif;line-height:15.6px">Lua does not allow the =
assignment operator to be overloaded and has no meta function for it. I hav=
e got around this by using the proxy pattern and the __index/__newindex met=
a methods.</p><p style=3D"margin:0px 0px 1em;padding:0px;border:0px;font-si=
ze:15px;clear:both;font-family:&#39;Helvetica Neue&#39;,Helvetica,Arial,san=
s-serif;line-height:15.6px">Now I have begun using classes defined via luab=
ind&#39;s object oriented system thats exposed to Lua.</p><p style=3D"margi=
n:0px 0px 1em;padding:0px;border:0px;font-size:15px;clear:both;font-family:=
&#39;Helvetica Neue&#39;,Helvetica,Arial,sans-serif;line-height:15.6px">I a=
m wondering if the C++ code for Luabind can be changed to allow the assignm=
ent operator to be overloaded without changing the code for the Lua interpr=
etor itself.</p><p style=3D"margin:0px 0px 1em;padding:0px;border:0px;font-=
size:15px;clear:both;font-family:&#39;Helvetica Neue&#39;,Helvetica,Arial,s=
ans-serif;line-height:15.6px">Perhaps such a overload would call into a new=
 meta-method name thats not used by Lua such as &#39;__assign()&#39;</p><p =
style=3D"margin:0px 0px 1em;padding:0px;border:0px;font-size:15px;clear:bot=
h;font-family:&#39;Helvetica Neue&#39;,Helvetica,Arial,sans-serif;line-heig=
ht:15.6px">This would not conflict with any meta method that Lua already us=
es and would apply only to instances of luabind classes.</p><p style=3D"mar=
gin:0px 0px 1em;padding:0px;border:0px;font-size:15px;clear:both;font-famil=
y:&#39;Helvetica Neue&#39;,Helvetica,Arial,sans-serif;line-height:15.6px">I=
 am guessing that the luabind::adl::object class needs to be changed, or pe=
rhaps index_proxy. But I am not sufficiently familiar with how luabind forw=
ards calls to existing Lua meta-methods, to its objects.</p><p style=3D"mar=
gin:0px 0px 1em;padding:0px;border:0px;font-size:15px;clear:both;font-famil=
y:&#39;Helvetica Neue&#39;,Helvetica,Arial,sans-serif;line-height:15.6px">H=
as anyone explored the C++ code in luabind that supports operator overloadi=
ng in Lua?</p><p style=3D"margin:0px 0px 1em;padding:0px;border:0px;font-si=
ze:15px;clear:both;font-family:&#39;Helvetica Neue&#39;,Helvetica,Arial,san=
s-serif;line-height:15.6px">Edit: I see some attempts to add a new operator=
 here:=C2=A0<a href=3D"https://github.com/decimad/luabind-deboostified/comm=
it/55b1bd9217205253b41ab7d4746637ee5b0d276f" rel=3D"nofollow" style=3D"marg=
in:0px;padding:0px;border:0px;text-decoration:none;color:rgb(12,101,165)">h=
ttps://github.com/decimad/luabind-deboostified/commit/55b1bd9217205253b41ab=
7d4746637ee5b0d276f</a></p><p style=3D"margin:0px 0px 1em;padding:0px;borde=
r:0px;font-size:15px;clear:both;font-family:&#39;Helvetica Neue&#39;,Helvet=
ica,Arial,sans-serif;line-height:15.6px">If I try the above with the assign=
ment operator though, I do no see it getting called in Lua. Are there any o=
ther changes needed in C++ for this?</p><p style=3D"margin:0px 0px 1em;padd=
ing:0px;border:0px;clear:both"><font face=3D"Helvetica Neue, Helvetica, Ari=
al, sans-serif"><span style=3D"font-size:15px;line-height:15.6px"><a href=
=3D"http://stackoverflow.com/questions/33141507/adding-an-overload-for-the-=
assignment-operator-in-lua-for-luabind-classes">http://stackoverflow.com/qu=
estions/33141507/adding-an-overload-for-the-assignment-operator-in-lua-for-=
luabind-classes</a></span></font><br></p><p style=3D"margin:0px 0px 1em;pad=
ding:0px;border:0px;font-size:15px;clear:both;font-family:&#39;Helvetica Ne=
ue&#39;,Helvetica,Arial,sans-serif;line-height:15.6px">Thanks,</p><p style=
=3D"margin:0px 0px 1em;padding:0px;border:0px;font-size:15px;clear:both;fon=
t-family:&#39;Helvetica Neue&#39;,Helvetica,Arial,sans-serif;line-height:15=
.6px">Abhi</p><p style=3D"margin:0px 0px 1em;padding:0px;border:0px;font-si=
ze:15px;clear:both;font-family:&#39;Helvetica Neue&#39;,Helvetica,Arial,san=
s-serif;line-height:15.6px"><br></p><p style=3D"margin:0px 0px 1em;padding:=
0px;border:0px;font-size:15px;clear:both;font-family:&#39;Helvetica Neue&#3=
9;,Helvetica,Arial,sans-serif;line-height:15.6px"><br></p></div>

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