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digitalmars.D - typeid() woes

reply Andrej Mitrovic <andrej.mitrovich gmail.com> writes:
test.d:

class Contact
{
}

class Friend : Contact
{    
    void reminder()
    {
        writeln("friend.reminder");
    }
}

unittest
{
    Contact c = new Friend; // c has type Contact but really refers to a Friend
    
    writeln(typeid(c));
    c.reminder();
}

This will not compile, as expected, since a Contact type doesn't have the
reminder method.

But if I comment out the c.reminder() line, writeln will return "test.Friend".
Why is that?
Aug 08 2010
next sibling parent reply Andrej Mitrovic <andrej.mitrovich gmail.com> writes:
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I need to be a little patient. :) On the next page it explains the static
vs. dynamic type, so I guess typeid() always returns the dynamic type. I
wonder if there's a way to get the static type, is there an equivalent
function like typeid() for such a case?

On Sun, Aug 8, 2010 at 11:57 PM, Andrej Mitrovic <andrej.mitrovich gmail.com

 wrote:




 test.d:

 class Contact
 {
 }

 class Friend : Contact
 {
    void reminder()
    {
        writeln("friend.reminder");
    }
 }

 unittest
 {
    Contact c = new Friend; // c has type Contact but really refers to a
 Friend

    writeln(typeid(c));
    c.reminder();
 }

 This will not compile, as expected, since a Contact type doesn't have the
 reminder method.

 But if I comment out the c.reminder() line, writeln will return
 "test.Friend". Why is that?



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I need to be a little patient. :) On the next page it explains the static v=
s. dynamic type, so I guess typeid() always returns the dynamic type. I won=
der if there&#39;s a way to get the static type, is there an equivalent fun=
ction like typeid() for such a case?<br>
<br><div class=3D"gmail_quote">On Sun, Aug 8, 2010 at 11:57 PM, Andrej Mitr=
ovic <span dir=3D"ltr">&lt;<a href=3D"mailto:andrej.mitrovich gmail.com">an=
drej.mitrovich gmail.com</a>&gt;</span> wrote:<br><blockquote class=3D"gmai=
l_quote" style=3D"margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204=
, 204, 204); padding-left: 1ex;">
test.d:<br>
<br>
class Contact<br>
{<br>
}<br>
<br>
class Friend : Contact<br>
{<br>
 =A0 =A0void reminder()<br>
 =A0 =A0{<br>
 =A0 =A0 =A0 =A0writeln(&quot;friend.reminder&quot;);<br>
 =A0 =A0}<br>
}<br>
<br>
unittest<br>
{<br>
 =A0 =A0Contact c =3D new Friend; // c has type Contact but really refers t=
o a Friend<br>
<br>
 =A0 =A0writeln(typeid(c));<br>
 =A0 =A0c.reminder();<br>
}<br>
<br>
This will not compile, as expected, since a Contact type doesn&#39;t have t=
he reminder method.<br>
<br>
But if I comment out the c.reminder() line, writeln will return &quot;test.=
Friend&quot;. Why is that?<br>
</blockquote></div><br>

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Aug 08 2010
parent bearophile <bearophileHUGS lycos.com> writes:
Andrej Mitrovic:

 I wonder if there's a way to get the static type, is there an equivalent
 function like typeid() for such a case?



Try typeof().

Bye,
bearophile
Aug 08 2010
prev sibling next sibling parent Adam Ruppe <destructionator gmail.com> writes:
On 8/8/10, Andrej Mitrovic <andrej.mitrovich gmail.com> wrote:

 I wonder if there's a way to get the static type, is there an equivalent
 function like typeid() for such a case?



Try this:

      typeid(typeof( X ));

typeof() returns the static type of the variable. Then, you can get
the typeid of that returned static type.

Here's a sample program:
====
import std.stdio;
class Something { }
class SomethingElse : Something {}

void main() {
        Something o = new SomethingElse;
        writeln(typeid(typeof(o)));
}
====
Prints: test6.Something
Aug 08 2010
prev sibling parent Andrej Mitrovic <andrej.mitrovich gmail.com> writes:
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Thanks, that works.

On Mon, Aug 9, 2010 at 12:21 AM, Adam Ruppe <destructionator gmail.com>wrote:


 On 8/8/10, Andrej Mitrovic <andrej.mitrovich gmail.com> wrote:

 I wonder if there's a way to get the static type, is there an equivalent
 function like typeid() for such a case?



 Try this:

      typeid(typeof( X ));

 typeof() returns the static type of the variable. Then, you can get
 the typeid of that returned static type.

 Here's a sample program:
 ====
 import std.stdio;
 class Something { }
 class SomethingElse : Something {}

 void main() {
        Something o = new SomethingElse;
        writeln(typeid(typeof(o)));
 }
 ====
 Prints: test6.Something



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Thanks, that works.<br><br><div class=3D"gmail_quote">On Mon, Aug 9, 2010 a=
t 12:21 AM, Adam Ruppe <span dir=3D"ltr">&lt;<a href=3D"mailto:destructiona=
tor gmail.com">destructionator gmail.com</a>&gt;</span> wrote:<br><blockquo=
te class=3D"gmail_quote" style=3D"margin: 0pt 0pt 0pt 0.8ex; border-left: 1=
px solid rgb(204, 204, 204); padding-left: 1ex;">
<div class=3D"im">On 8/8/10, Andrej Mitrovic &lt;<a href=3D"mailto:andrej.m=
itrovich gmail.com">andrej.mitrovich gmail.com</a>&gt; wrote:<br>
&gt; I wonder if there&#39;s a way to get the static type, is there an equi=
valent<br>
&gt; function like typeid() for such a case?<br>
<br>
</div>Try this:<br>
<br>
 =A0 =A0 =A0typeid(typeof( X ));<br>
<br>
typeof() returns the static type of the variable. Then, you can get<br>
the typeid of that returned static type.<br>
<br>
Here&#39;s a sample program:<br>
=3D=3D=3D=3D<br>
import std.stdio;<br>
class Something { }<br>
class SomethingElse : Something {}<br>
<br>
void main() {<br>
 =A0 =A0 =A0 =A0Something o =3D new SomethingElse;<br>
 =A0 =A0 =A0 =A0writeln(typeid(typeof(o)));<br>
}<br>
=3D=3D=3D=3D<br>
Prints: test6.Something<br>
</blockquote></div><br>

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Aug 08 2010