Better Expression As A Parameter Handling

[kanonet]

The string problems that i described in an other Thread are  gone with this hotfix.
But bigsofty's problem from this thread still exist.

[bigsofty]

Yes, the DIMDATA bug has neen squashed but the type reference problems that were described at the beginning of this thread still exists. 

Code (glbasic) Select Expand

*** Configuration: WIN32 ***
precompiling:
GPC - GLBasic Precompiler V.10.079 SN:2e101695 - 3D, NET
Wordcount:10 commands
compiling:
C:\Users\Dad\AppData\Local\Temp\glbasic\gpc_temp0.cpp: In function `DGInt __GLBASIC__::caller()':
C:\Users\Dad\AppData\Local\Temp\glbasic\gpc_temp0.cpp:109: error: invalid initialization of non-const reference of type '__GLBASIC__::TVec3&' from a temporary of type '__GLBASIC__::TVec3'
C:\Users\Dad\AppData\Local\Temp\glbasic\gpc_temp.h:10: error: in passing argument 1 of `DGInt __GLBASIC__::vecfunc(__GLBASIC__::TVec3&)'
*** FATAL ERROR - Please post this output in the forum
_______________________________________
*** Finished ***
Elapsed: 1.1 sec. Time: 22:49
Build: 0 succeeded.
*** 1 FAILED ***

[MrTAToad]

We will give it a test

[Kitty Hello]

Oh dear. I think it's because of my emergency return value when you forget to return anything.
I'll keep digging...

[edit]
oh no!!!

Code (glbasic) Select Expand


Tvec foo()
{
   Tvec; v; return v;
}
void bar(Tvec& v)
{
}
int main()
{
   bar(foo() );
}


In C++ an "rvalue" (the return thing of a function e.g.) cannot be passed as a reference to a function. It might be passed as a const reference, but then it would not allow you to modify the object passed.

So... You would need a temporary object to pass to this function. The only thing I could think of would be an BYVAL keyword for arguments.

[bigsofty]

This would be fine Gernot, Delphi and C# have keywords for variables that are passed as parameters by reference. Which would be fine for me too. 

[bigsofty]

Here's a rather strange thing, it may be related it may be not.

This function...

Code (glbasic) Select Expand

// Convert a 2D x,y to 3D vec
FUNCTION v2D23D AS TVec3: vec2D AS TVec2, z#=0
LOCAL vec3D AS TVec3
INLINE
return vec3D.SetUp(vec2D.x-screenCentre.x,-vec2D.y+screenCentre.y,z);
ENDINLINE
RETURN vec3D.SetUp(vec2D.x-screenCentre.x,-vec2D.y+screenCentre.y,z)
ENDFUNCTION

Actually creates the same return C code ("return vec3D.SetUp(vec2D.x-screenCentre.x,-vec2D.y+screenCentre.y,z);")...

Code (glbasic) Select Expand

// Convert a 2D x,y to 3D vec.
// ------------------------ //
TVec3 v2D23D(TVec2& vec2D, DGInt z)
{
   __PPRegisterFunction
  #undef __FKT
  #define __FKT __l_dbg_cont
  __VAR_CONTAINER __FKT;
ARGS_VAR(TVec2, vec2D);
ARGS_VAR(DGInt, z);

#undef __GLBNO__
#define __GLBNO__ 258

#undef __GLBNO__
#define __GLBNO__ 259
ON_DEBUG(12,259);
REGISTER_VAR(TVec3, vec3D);

#undef __GLBNO__
#define __GLBNO__ 260
ON_DEBUG(12,260);

/* ---- INLINE ---- */

return vec3D.SetUp(vec2D.x-screenCentre.x,-vec2D.y+screenCentre.y,z);


/* ---- ENDINLINE ---- */

#undef __GLBNO__
#define __GLBNO__ 262

#undef __GLBNO__
#define __GLBNO__ 263
ON_DEBUG(12,263);
return vec3D.SetUp(vec2D.x-screenCentre.x,-vec2D.y+screenCentre.y,z);

#undef __GLBNO__
#define __GLBNO__ 264

#undef __GLBNO__
#define __GLBNO__ 265
ON_DEBUG(12,265);
return TVec3();
}

Yet, the pre-compiler throws an error ""misc.gbas"(316) error : GPC0007 wrong argument type :" for the GLBasic RETURN line?

If I remark the GLBasic RETURN line out it works as expected, using the inline C for the return value as expected.


Oh, here is the TYPE that is called.

Code (glbasic) Select Expand

TYPE TVec3

x#
y#
z#
w# = 1

FUNCTION SetUp AS TVec3: x#, y#, z#
self.x#=x#; self.y#=y#; self.z#=z#
RETURN self
ENDFUNCTION

ENDTYPE


[jestermon]

I may be going a bit overboard with my enthusiasm, but heck, it's not everyday that small code snippit posts tell me more than weeks of searching. So again, my thanks for showing a "returnable" self - in full working context in GLB.
I'm still not used to this level of coding in any version of the Basic language.

[bigsofty]

You very welcome Jestermon. I think maybe the description of GLBs advanced types needs more documentation in the manual to help people digest this, extremely usefull, aspect of the GLBasic language?