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Setting Types in C

BlitzMax Forums/BlitzMax Programming/Setting Types in C

Vertex(Posted 2008) [#1]
Hi!

How can I set String Fields of BlitzMax Types in an external C function?

I've tried the following:
ref.bmx
SuperStrict

Framework BRL.Blitz

Import "ref.c"
Extern "C"
	Function getTest(test:Byte Ptr)
End Extern

Type TTest
	Field Foo:String
	Field Bar:String
	Field Info:String
	
	Method Debug()
		DebugLog(Foo + " " + Bar + " " + Info)
	End Method
End Type

Local test:TTest = New TTest

For Local i:Int = 0 Until 100
	getTest(test)
	test.Debug()
	Delay 100
Next

End


ref.c
#include <brl.mod/blitz.mod/blitz.h>
#include <windows.h>

typedef struct {
	BBString *Foo;
	BBString *Bar;
	BBString *Info;
} TTEST;

void getTest(TTEST *test) {
	BBRELEASE(test->Foo);
	BBRELEASE(test->Bar);
	BBRELEASE(test->Info)

	test->Foo = bbStringFromCString("Foo");
	test->Bar = bbStringFromCString("Bar");

	char info[255];
	sprintf(info, "%d ms", GetTickCount());
	test->Info = bbStringFromCString(info);
}


both in the same directory.

When I try to run ref.bmx in the debug mode I'am getting:
DebugLog:Foo Bar 2200671 ms
DebugLog:Foo Bar 2200765 ms
DebugLog:Foo Bar 2200875 ms
DebugLog:Foo Bar 2200968 ms
bad refs:obj=$c30670 refs=$7fffffff
String:Foo
bad refs:obj=$c30690 refs=$7fffffff
String:Bar
bad refs:obj=$c306b0 refs=$7fffffff
String:2195937 ms
bad refs:obj=$c30800 refs=$7fffffff
String:Foo
bad refs:obj=$c30820 refs=$7fffffff
String:Bar
...


When I comment out the BBRELEASE-Macro calls, I'am getting false results like:
DebugLog:Bar Bar 2554250 ms
DebugLog:Foo 2616703 ms 2616703 ms


So, how can I set BBStrings-Fields in C correctly?

cu olli


Brucey(Posted 2008) [#2]
You can't do that in C with BlitzMax... The two "types" are not compatible. There are some posts on the forums which explain how to do something like you want with C++.

And you really don't want to be calling BBRELEASE() if you don't know what you're doing :-p


Vertex(Posted 2008) [#3]
Hmm, OK thx! ...

It's possible to setting 3 String via calling by reference? Like a function
void getTest2(BBString *Foo, BBString *Bar, BBString *Info) {
	Foo = bbStringFromCString("Foo");
	Bar = bbStringFromCString("Bar");

	char info[255];
	sprintf(info, "%d ms", GetTickCount());
	Info = bbStringFromCString(info);
}


Whats the extern block for it in BMax? String Ptr isn't possible.

cu olli


Gabriel(Posted 2008) [#4]
Any generic pointer can be defined as Byte Ptr.


Vertex(Posted 2008) [#5]
No way with Byte Ptr, my Strings are alway empty :(

So whats with C++? I've tested this:
Ref.cpp
#include <brl.mod/blitz.mod/blitz.h>
#include <windows.h>

class TTest {
public:
	BBString *a;
	BBString *b;
	BBString *c;

	TTest() {
		a = &bbEmptyString;
		b = &bbEmptyString;
		c = &bbEmptyString;
	}

	virtual ~TTest() {
		a = &bbEmptyString;
		b = &bbEmptyString;
		c = &bbEmptyString;
	}
	
	virtual void getTest() {
		a = bbStringFromCString("Foo");
		b = bbStringFromCString("Bar");
	
		char info[255];
		sprintf(info, "%d ms", GetTickCount());
		c = bbStringFromCString(info);
	}
};


extern "C" {

TTest *CreateTTest(){
	return new TTest;
}

void DestroyTTest(TTest *test) {
	delete test;
}

}


Ref.bmx
SuperStrict

Framework BRL.Blitz

Import "ref.cpp"

Extern 

Type TTest
	Field a : String
	Field b : String
	Field c : String

	Method _pad1() ' padding for virtual destructors
	Method _pad2()
	Method getTest()
End Type

Function CreateTTest:TTest()
Function DestroyTTest(test:TTest)

End Extern

Local test:TTest = CreateTTest()
For Local i:Int = 0 Until 1000
	test.getTest()
	DebugLog test.a + " " + test.b + " " + test.c
	Delay 10
Next

DestroyTTest(test)


Getting some times output like:
DebugLog:FooDebugLog:Foo Bar 4498281 ms
...
DebugLog:Foo 4500109 ms 4500109 ms


Whats wrong?

cu olli


REDi(Posted 2008) [#6]
I ended up using getters/setters for stuff like that, and I use cstring($z) to save messing about with BBString.

cpp...


bmx..


Maybe not ideal, but it works ;)


Vertex(Posted 2008) [#7]
OK, thank you, thats the way I will going :) I've tested it with 
virtual BBString *getA() {
	return bbStringFromCString(a);
}

and it works without bad refs or unexpected results too :)

cu olli