From: Luis C <luis.camp0.2009@...>
Date: 2016-10-10T13:43:44+01:00
Subject: [ruby-core:77538] ruby callback issue (no implicit conversion of	nil into String)

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Hi all,

The following code was working with swig 3.0 and with ruby < 2.3. So
probably the problem is on the ruby interpreter. However, because I just
swig to wrap the classes may be is something wrong on the definition or I
miss something. I got the error "no implicit conversion of nil into String
(TypeError)" from the callback parameter but if I access from a new
instance, works. This have been working in old versions of ruby. Any
similar problems?

File compile.sh
#!/bin/bash

swig -globalmodule -c++ -ruby ruby_wrapper.i
g++ -fPIC -std=c++11 -I/usr/include/ruby -c Callback.cc
ruby_wrapper_wrap.cxx
g++ -fPIC -shared -std=c++11 Callback.o ruby_wrapper_wrap.o -o example.so
-lruby

File Callback.h
#ifndef SRC_CALLBACK_H_
#define SRC_CALLBACK_H_

#include <iostream>
#include "MyClass.h"
#include <ruby.h>


class Callback
{
public:
    Callback():callback_set_(false),callback_(Qnil),memory_wrapper_(Qnil),cc("another")
{
        memory_wrapper_ = Data_Wrap_Struct(0 /* klass */, staticMark, NULL,
static_cast<void*>(this));
        rb_gc_register_address(&memory_wrapper_);

    }
    virtual ~Callback() { rb_gc_unregister_address(&memory_wrapper_);}

    bool haveCallback() const { return callback_set_;}

    void setCallback(VALUE callback);
    void executeCallback(MyClass *c);

    void run();

protected:
    static void staticMark(Callback *me) { me->mark(); }

    void mark();
private:
    bool callback_set_;
    VALUE callback_;
    VALUE memory_wrapper_;
    MyClass cc;
};

#endif  // SRC_CALLBACK_H_

File Callback.cc
#include "Callback.h"

void Callback::setCallback(VALUE callback) {

    if (!NIL_P(callback)) {
        // Verify the number of arguments of the callback by calling the
method arity

        VALUE value = rb_funcall(callback,rb_intern("arity"),0);
        int nargs = NUM2INT(value);

        if (nargs != 1) {
            rb_raise(rb_eRuntimeError,"Object should have one
parameter.\n");
        }

            callback_ = callback;
                callback_set_ = true;
    } else {
            callback_ = Qnil;
                callback_set_ = false;
    }
}


void Callback::executeCallback(MyClass *c) {

    if (!NIL_P(callback_)) {
        ID id = rb_intern("MyClass");
        if (rb_const_defined(rb_cObject, id)) {
                        VALUE rbClass = rb_const_get(rb_cObject,id);
                    VALUE rbData = Data_Wrap_Struct(rbClass, 0, 0, c);
                   rb_funcall(callback_,rb_intern("call"), 1, rbData);
        }
        }
}

void Callback::run() {

    executeCallback(&cc);
}


void Callback::mark() {

    if (!NIL_P(callback_)) {
            rb_gc_mark(callback_);
        }
}

File MyClass.h
#ifndef SRC_MYCLASS_H_
#define SRC_MYCLASS_H_

#include <iostream>


class MyClass
{
public:
    MyClass():name_("default value"),value_(0) {}
    MyClass(const std::string name): name_(name),value_(0) {}
    virtual ~MyClass() {}

    int getInt() { return value_; }
    void setInt(int value) { value_ = value; }

    const char *getName() const { return name_.c_str(); }
private:
    std::string name_;
    int value_;
};

#endif

File ruby_wrapper.i
%module(directors="1") example
%include <std_string.i>

%{
#include <iostream>
#include "Callback.h"
#include "MyClass.h"

using namespace std;
%}

%trackobjects;

%rename("my_name") MyClass::getName;
%rename("my_int") MyClass::getInt;
%rename("my_int=") MyClass::setInt;
%rename("callback=") Callback::setCallback;

%include "MyClass.h"
%include "Callback.h"

File test.rb
require './example'

def callback(cc)
  print("From the callback")
  print(cc.methods.sort)
  print(cc.my_int)
  print(cc.my_name)
end

puts "Testing example"

a = MyClass.new()

print("From the main")
print(a.methods.sort)
puts a.my_name
puts a.my_int

c = Callback.new()

c.callback = method(:callback)

c.run()

This code is working in ruby versions < 2.1, Any one have this problem?
other way to pass the c++ mapped object as parameter to the callback?

Thanks and regards,
Luis

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<div dir=3D"ltr"><div style=3D"font-size:12.8px"><div>Hi all,<br><br></div>=
The following code=20
was working with swig 3.0 and with ruby &lt; 2.3. So probably the=20
problem is on the ruby interpreter. However, because I just swig to wrap
 the classes may be is something wrong on the definition or I miss=20
something. I got the error &quot;no implicit conversion of nil into String=
=20
(TypeError)&quot; from the callback parameter but if I access from a new in=
stance,=20
works. This have been working in old versions of ruby. Any similar=20
problems?<br><br></div><div style=3D"font-size:12.8px">File compile.sh<br><=
/div><div style=3D"font-size:12.8px">#!/bin/bash<br><br>swig -globalmodule =
-c++ -ruby ruby_wrapper.i =C2=A0=C2=A0=C2=A0=C2=A0<br>g++ -fPIC -std=3Dc++1=
1 -I/usr/include/ruby -c Callback.cc ruby_wrapper_wrap.cxx=C2=A0<br>g++ -fP=
IC -shared -std=3Dc++11 Callback.o ruby_wrapper_wrap.o -o example.so -lruby=
<br><br></div><div style=3D"font-size:12.8px">File Callback.h<br>#ifndef SR=
C_CALLBACK_H_<br>#define SRC_CALLBACK_H_<br><br>#include &lt;iostream&gt;<b=
r>#include &quot;MyClass.h&quot;<br>#include &lt;ruby.h&gt;<br><br><br>clas=
s Callback=C2=A0<br>{<br>public:<br>=C2=A0=C2=A0=C2=A0 Callback():callback_=
set_(false<wbr>),callback_(Qnil),memory_wrapp<wbr>er_(Qnil),cc(&quot;anothe=
r&quot;) {<br>=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 memory_wrapper_ =3D Dat=
a_Wrap_Struct(0 /* klass */, staticMark, NULL, static_cast&lt;void*&gt;(thi=
s));<br>=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 rb_gc_register_address(&amp;m=
emory<wbr>_wrapper_);<br><br>=C2=A0=C2=A0=C2=A0 }<br>=C2=A0=C2=A0=C2=A0 vir=
tual ~Callback() { rb_gc_unregister_address(&amp;memo<wbr>ry_wrapper_);}<br=
><br>=C2=A0=C2=A0=C2=A0 bool haveCallback() const { return callback_set_;}<=
br>=C2=A0=C2=A0=C2=A0=C2=A0<br>=C2=A0=C2=A0=C2=A0 void setCallback(VALUE ca=
llback);<br>=C2=A0=C2=A0=C2=A0 void executeCallback(MyClass *c);=C2=A0<br><=
br>=C2=A0=C2=A0=C2=A0 void run();<br>=C2=A0=C2=A0=C2=A0=C2=A0<br>protected:=
<br>=C2=A0=C2=A0=C2=A0 static void staticMark(Callback *me) { me-&gt;mark()=
; }<br><br>=C2=A0=C2=A0=C2=A0 void mark();<br>private:<br>=C2=A0=C2=A0=C2=
=A0 bool callback_set_;<br>=C2=A0=C2=A0=C2=A0 VALUE callback_;<br>=C2=A0=C2=
=A0=C2=A0 VALUE memory_wrapper_;<br>=C2=A0=C2=A0=C2=A0 MyClass cc;<br>};<br=
><br>#endif=C2=A0 // SRC_CALLBACK_H_<br><br></div><div style=3D"font-size:1=
2.8px">File Callback.cc<br>#include &quot;Callback.h&quot;<br><br>void Call=
back::setCallback(VALUE callback) {<br><br>=C2=A0=C2=A0=C2=A0 if (!NIL_P(ca=
llback)) {<br>=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 // Verify the number of=
 arguments of the callback by calling the method arity<br><br>=C2=A0=C2=A0=
=C2=A0 =C2=A0=C2=A0=C2=A0 VALUE value =3D rb_funcall(callback,rb_intern(<wb=
r>&quot;arity&quot;),0);<br>=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 int nargs=
 =3D NUM2INT(value);<br><br>=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 if (nargs=
 !=3D 1) {<br>=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 rb_r=
aise(rb_eRuntimeError,&quot;Obj<wbr>ect should have one parameter.\n&quot;)=
;<br>=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 }=C2=A0=C2=A0=C2=A0=C2=A0<br><br=
>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 callback_ =
=3D callback;<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 callback_set_ =3D true;<br>=C2=A0=C2=A0=
=C2=A0 } else {<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=
=C2=A0 callback_ =3D Qnil;<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 callback_set_ =3D false;<br>=
=C2=A0=C2=A0=C2=A0 }<br>}<br><br><br>void Callback::executeCallback(MyCl<wb=
r>ass *c) {<br><br>=C2=A0=C2=A0=C2=A0 if (!NIL_P(callback_)) {<br>=C2=A0=C2=
=A0=C2=A0 =C2=A0=C2=A0=C2=A0 ID id =3D rb_intern(&quot;MyClass&quot;);<br>=
=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 if (rb_const_defined(rb_cObject, id))=
 {=C2=A0=C2=A0=C2=A0=C2=A0<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0 VALUE rbClass =3D rb_const_get(rb_cObject,id);<br>=C2=A0=
=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=
=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 VALUE rbData =3D Data_Wrap_Struct(rbClass, 0=
, 0, c);=C2=A0=C2=A0=C2=A0=C2=A0<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 =
=C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 =C2=A0=C2=A0=C2=A0 rb_funcall(callbac=
k_,rb_intern<wbr>(&quot;call&quot;), 1, rbData);<br>=C2=A0=C2=A0=C2=A0 =C2=
=A0=C2=A0=C2=A0 }<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 }<br>}<br><=
br>void Callback::run() {<br><br>=C2=A0=C2=A0=C2=A0 executeCallback(&amp;cc=
);<br>}<br><br><br>void Callback::mark() {<br><br>=C2=A0=C2=A0=C2=A0 if (!N=
IL_P(callback_)) {<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0 =C2=A0=C2=
=A0=C2=A0 rb_gc_mark(callback_);<br>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=
=A0 }<br>}<br><br></div><div style=3D"font-size:12.8px">File MyClass.h<br>#=
ifndef SRC_MYCLASS_H_<br>#define SRC_MYCLASS_H_<br><br>#include &lt;iostrea=
m&gt;<br><br><br>class MyClass=C2=A0<br>{<br>public:<br>=C2=A0=C2=A0=C2=A0 =
MyClass():name_(&quot;default value&quot;),value_(0) {}<br>=C2=A0=C2=A0=C2=
=A0 MyClass(const std::string name): name_(name),value_(0) {}<br>=C2=A0=C2=
=A0=C2=A0 virtual ~MyClass() {}=C2=A0<br><br>=C2=A0=C2=A0=C2=A0 int getInt(=
) { return value_; }<br>=C2=A0=C2=A0=C2=A0 void setInt(int value) { value_ =
=3D value; }<br><br>=C2=A0=C2=A0=C2=A0 const char *getName() const { return=
 name_.c_str(); }<br>private:<br>=C2=A0=C2=A0=C2=A0 std::string name_;=C2=
=A0=C2=A0=C2=A0=C2=A0<br>=C2=A0=C2=A0=C2=A0 int value_;<br>};<br><br>#endif=
<br><br></div><div style=3D"font-size:12.8px">File ruby_wrapper.i<br>%modul=
e(directors=3D&quot;1&quot;) example=C2=A0<br>%include &lt;std_string.i&gt;=
<br><br>%{<br>#include &lt;iostream&gt;<br>#include &quot;Callback.h&quot;<=
br>#include &quot;MyClass.h&quot;<br><br>using namespace std;<br>%}<br><br>=
%trackobjects;<br><br>%rename(&quot;my_name&quot;) MyClass::getName;<br>%re=
name(&quot;my_int&quot;) MyClass::getInt;<br>%rename(&quot;my_int=3D&quot;)=
 MyClass::setInt;<br>%rename(&quot;callback=3D&quot;) Callback::setCallback=
;<br><br>%include &quot;MyClass.h&quot;<br>%include &quot;Callback.h&quot;<=
br><br></div><div style=3D"font-size:12.8px">File test.rb<br>require &#39;.=
/example&#39;<br><br>def callback(cc)=C2=A0<br>=C2=A0 print(&quot;From the =
callback&quot;)<br>=C2=A0 print(cc.methods.sort)<br>=C2=A0 print(cc.my_int)=
<br>=C2=A0 print(cc.my_name)<br>end<br><br>puts &quot;Testing example&quot;=
<br><br>a =3D MyClass.new()<br><br>print(&quot;From the main&quot;)<br>prin=
t(a.methods.sort)<br>puts a.my_name<br>puts a.my_int<br><br>c =3D Callback.=
new()<br><br>c.callback =3D method(:callback)<br><br>c.run()<br><br></div><=
div style=3D"font-size:12.8px">This
 code is working in ruby versions &lt; 2.1, Any one have this problem?=20
other way to pass the c++ mapped object as parameter to the callback?<br></=
div><div style=3D"font-size:12.8px"><br></div><div style=3D"font-size:12.8p=
x">Thanks and regards,<br></div><span style=3D"font-size:12.8px">Luis</span=
></div>

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