Re: [Swig-user] passing primitive types and enums by reference in java

[Xu, Z. <zho...@no...>]

Nathan,

You can use these:

%include "typemaps.i"

%apply float & OUTPUT { float &x };
%apply float & OUTPUT { float &y };
%apply float & OUTPUT { float &z };


Best Regards, 
Milo


-----Original Message-----
From: Mr. Nathan [mailto:na...@te...] 
Sent: 2009年2月18日 3:18
To: swi...@li...
Subject: [Swig-user] passing primitive types and enums by reference in java


I'd like to wrap a series of get() functions that write the requested information into an argument passed into it by reference.  The return value is reserved for state and error code information.  This appears to work for class types, but fails with enums and primitive types.  For example, see the following C++ code:

//this works
bool GetPoint(Point & pt);

//but this doesn't
bool GetPoint(float &x, float &y, float &z);

In reading the documentation I came across this line which made me a bit concerned, "Since most Java primitive types are immutable and are passed by value, it is not possible to perform in-place modification of a type passed as a parameter."  Is there a recommended way to skirt this problem?  

In some of our old wrapper code we use arrays of primitives to bump them up to reference types.  It also seems like generating wrapper classes for primitives might work.  However, each of these approaches has its own drawbacks.  Using arrays forces programmers to use a rather unnatural syntax.  While wrapper classes would require wrapping of all primitive types and make enum comparison cumbersome.

I'm sure I'm not the first person to encounter this problem.  Is there a standard solution?  Should I accept one of the above possibilities, or just suck it up and rewrite the interface to return the value directly?

Thanks in advance,
.-=/|N|¥=-.
--
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