# dynamic_cast howto?

#1
void myEdtor::setValues()
{
for (int x=0; x<getNumChildComponents(); x++)
{
Component		*c			= getChildComponent(x);
Slider			*slider		= dynamic_cast <Slider*> (c);
ToggleButton	*btn		= dynamic_cast <ToggleButton*> (c);

if (slider != 0)
{
slider->setValue (3);
continue;
}

if (btn != 0)
{
btn->setToggleState (1, false);
continue;
}
}
}

i’d like to set all values for certain type of components (children of myEdtor component), if i use a method like that one (i took the dynamic_cast thinggy from juce’s Component source), i get memory leaks:

Object dump complete.
Detected memory leaks!
Dumping objects ->
{21211} normal block at 0x04956DB8, 8 bytes long.
Data: <        > 03 CD CD CD 88 AE 95 04
{21210} normal block at 0x0495D5A0, 8 bytes long.
Data: <        > 03 CD CD CD D8 D8 7F 04
{21209} normal block at 0x047FC6C8, 8 bytes long.
Data: <    H   > 03 CD CD CD 48 C4 7F 04
{21208} normal block at 0x047FB2A8, 8 bytes long.
Data: <    (   > 03 CD CD CD 28 B0 7F 04
{21207} normal block at 0x047F2C80, 8 bytes long.
Data: <    h   > 03 CD CD CD 68 A1 7F 04
{21206} normal block at 0x047F13E0, 8 bytes long.
Data: <     #  > 03 CD CD CD A0 23 7F 04
{21205} normal block at 0x047F9A00, 8 bytes long.
Data: <        > 03 CD CD CD D8 08 7F 04
{21204} normal block at 0x047EA100, 8 bytes long.
Data: <    @ ~ > 03 CD CD CD 40 B2 7E 04
{21203} normal block at 0x047E38C8, 8 bytes long.
Data: <      ~ > 03 CD CD CD F8 95 7E 04
{21202} normal block at 0x047F4200, 8 bytes long.
Data: <    @S  > 03 CD CD CD 40 53 7F 04
{21201} normal block at 0x047E4C98, 8 bytes long.
Data: <     6  > 03 CD CD CD F8 36 7F 04
{21200} normal block at 0x047E3180, 8 bytes long.
Data: <    P   > 03 CD CD CD 50 87 7F 04
{21199} normal block at 0x0495D220, 8 bytes long.
Data: <      ~ > 03 CD CD CD 08 EE 7E 04
{21198} normal block at 0x04800290, 8 bytes long.
Data: <    P ~ > 03 CD CD CD 50 D2 7E 04
{21197} normal block at 0x047E67A0, 8 bytes long.
Data: <      ~ > 03 CD CD CD 80 7F 7E 04
{21196} normal block at 0x04800388, 8 bytes long.
Data: <     H~ > 03 CD CD CD B8 48 7E 04
c:\devel\juce\src\juce_core\text\juce_string.cpp(76) : {20787} normal block at 0x0495AE88, 36 bytes long.
Data: <        j u n o > 01 00 00 00 0C 00 00 00 6A 00 75 00 6E 00 6F 00
c:\devel\juce\src\juce_core\text\juce_string.cpp(76) : {20217} normal block at 0x047FD8D8, 32 bytes long.
Data: <        j u n o > 01 00 00 00 0A 00 00 00 6A 00 75 00 6E 00 6F 00
c:\devel\juce\src\juce_core\text\juce_string.cpp(76) : {19849} normal block at 0x047FC448, 40 bytes long.
Data: <        j u n o > 01 00 00 00 0E 00 00 00 6A 00 75 00 6E 00 6F 00
c:\devel\juce\src\juce_core\text\juce_string.cpp(76) : {19482} normal block at 0x047FB028, 40 bytes long.
Data: <        j u n o > 01 00 00 00 0E 00 00 00 6A 00 75 00 6E 00 6F 00
c:\devel\juce\src\juce_core\text\juce_string.cpp(76) : {19115} normal block at 0x047FA168, 36 bytes long.
Data: <        j u n o > 01 00 00 00 0C 00 00 00 6A 00 75 00 6E 00 6F 00
c:\devel\juce\src\juce_core\text\juce_string.cpp(76) : {18684} normal block at 0x047F23A0, 38 bytes long.
Data: <        j u n o > 01 00 00 00 0D 00 00 00 6A 00 75 00 6E 00 6F 00
c:\devel\juce\src\juce_core\text\juce_string.cpp(76) : {18349} normal block at 0x047F08D8, 32 bytes long.
Data: <        j u n o > 01 00 00 00 0A 00 00 00 6A 00 75 00 6E 00 6F 00
c:\devel\juce\src\juce_core\text\juce_string.cpp(76) : {17951} normal block at 0x047EB240, 32 bytes long.
Data: <        j u n o > 01 00 00 00 0A 00 00 00 6A 00 75 00 6E 00 6F 00
c:\devel\juce\src\juce_core\text\juce_string.cpp(76) : {17554} normal block at 0x047E95F8, 32 bytes long.
Data: <        j u n o > 01 00 00 00 0A 00 00 00 6A 00 75 00 6E 00 6F 00
c:\devel\juce\src\juce_core\text\juce_string.cpp(76) : {17155} normal block at 0x047F5340, 32 bytes long.
Data: <        j u n o > 01 00 00 00 0A 00 00 00 6A 00 75 00 6E 00 6F 00
c:\devel\juce\src\juce_core\text\juce_string.cpp(76) : {16758} normal block at 0x047F36F8, 34 bytes long.
Data: <        j u n o > 01 00 00 00 0B 00 00 00 6A 00 75 00 6E 00 6F 00
c:\devel\juce\src\juce_core\text\juce_string.cpp(76) : {16360} normal block at 0x047F8750, 34 bytes long.
Data: <        j u n o > 01 00 00 00 0B 00 00 00 6A 00 75 00 6E 00 6F 00
c:\devel\juce\src\juce_core\text\juce_string.cpp(76) : {16025} normal block at 0x047EEE08, 36 bytes long.
Data: <        j u n o > 01 00 00 00 0C 00 00 00 6A 00 75 00 6E 00 6F 00
c:\devel\juce\src\juce_core\text\juce_string.cpp(76) : {15689} normal block at 0x047ED250, 32 bytes long.
Data: <        j u n o > 01 00 00 00 0A 00 00 00 6A 00 75 00 6E 00 6F 00
c:\devel\juce\src\juce_core\text\juce_string.cpp(76) : {15354} normal block at 0x047E7F80, 32 bytes long.
Data: <        j u n o > 01 00 00 00 0A 00 00 00 6A 00 75 00 6E 00 6F 00
c:\devel\juce\src\juce_core\text\juce_string.cpp(76) : {15018} normal block at 0x047E48B8, 36 bytes long.
Data: <        j u n o > 01 00 00 00 0C 00 00 00 6A 00 75 00 6E 00 6F 00
Object dump complete.

if i comment out the setValue(), setToggleState() calls no memory leaks occur. This is a editor for a vst plugin and it’s initialization. What’s wrong here, and/or is there a better way to do this.

#2

There’s absolutely nothing wrong with your casting - the leaks must be coming from somewhere else. Since it’s leaking a string that starts “juno”, maybe the culprit is some debugging code, perhaps getting called by a listener callback when you change those values?

#3

…and make sure that when you change those values, it doesn’t alter the list of child components that you’re in the middle of iterating.

I’ve had a few bugs like that in my time…

#4

It seems that you are using Visual Studio.
There is a wonderful addin that helps finding memory leaks :
http://www.codeproject.com/KB/applications/visualleakdetector.aspx

#5

oh yeah i forgot about that, for now i’m trying to keep my code no to spit any of the jules included dumps, i guess if that will be clean VLD should be also, i checked what happpened and it was the setValue() for the components called the listener methods and that caused trouble, i added false as the second parameter and it’s all good now.