Types in Functions?? - GameCreators Forum

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pat1926

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Posted: 10th Jul 2003 10:17 Edited at: 10th Jul 2003 10:18

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First, I know thats not how you multiply vectors this is just an example.

That being said, i would like to know why when i try to run that function with a type i get an error. Is it possible to have a funciton with types as the inputs? Could someone Please clarify this for me.

Sorry didnt mean to double post. Dont know what happened.

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Shadow Robert

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Posted: 10th Jul 2003 10:27

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no it isn't... and we've not been told if it'll be added in the future either

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Philip

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Posted: 10th Jul 2003 19:21

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Might it be that you are trying to define a type with a name which is a reserved word? I think vector is a reserved word, right?

Its like defining a type as called "type" or "print", right?

Phil

What do you mean, bears aren't supposed to wear hats and a tie?

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pat1926

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Posted: 10th Jul 2003 19:27 Edited at: 10th Jul 2003 19:32

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No that vector thing was just an example, i am using a different word in my program

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IanM

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Posted: 10th Jul 2003 22:14

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Vector isn't a reserved word anyway...

But no, you can't pass types directly into functions.

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Shadowfax

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Posted: 11th Jul 2003 02:13

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Hi Pat

It is possible to
[1] (externally to the function) use make memory to aquire a block of memory of sufficient size

[2] write your data from your data type into the memory block

[3] pass the pointer to the memory block into the function as an integer

[4] (*VERY IMPORTANT*) cast the integer back into a pointer

[5] access the data from the memory block inside the function

...however
(1) firstly its a pain in the arse
(2) secondly you would really have to structure the code so most of your functions (to do this task) opperate in this manner and
(3) if your are not *extremely* careful, you can mistake a value for a pointer or vice versa and your code crashes to hell and back

Its not passing a data type but its as close as i have figured to get

"No Gir ... thats BAD !"

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Shadowfax

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Posted: 11th Jul 2003 02:16

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PS Anyone official will probably say you would be nuts to consider what i described but it does work for me

"No Gir ... thats BAD !"

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IanM

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Posted: 11th Jul 2003 02:45

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I'm no official, but you're nuts ...

It's probably easier to use a global array (as they can be expanded on the fly) and pass the index as the parameter.

(1) Firstly, it's easy
(2) secondly, it's easy
(3) thirdly, it's easy

No crashes, no memory leaks (DBPro handles the memory allocations), and you get to use structures (types) instead of offsets in memory.

+ Code Snippet

type MyType
a as integer
b as integer
endtype

global dim MyArray(0) as MyType
empty array MyArray()

i=Make_Mytype()
MyFunction(i)

function MyFunction(i as integer)
   MyArray(i).a=1
endfunction

function Make_MyType()
   array insert at bottom MyArray()
   exitfunction array count( MyArray() )
endfunction 0

If you wanted to get clever, you could record which items were in use (via another array) so that you could free and reallocate items in the array.

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swdave

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Posted: 11th Jul 2003 04:42

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It seems to be a BASIC feature that doesnt work. You can hard code your functions to use globals like so. Maybe the feature will get fixed and it will be easy to recode.

+ Code Snippet

TYPE Vector
 x AS FLOAT
 y AS FLOAT
 z AS FLOAT
ENDTYPE

v1 AS Vector
v2 AS Vector
v3 AS Vector

v1.x = 10
v1.y = 20
v1.z = 30

v2.x = 10
v2.y = 20
v2.z = 30

VectorMulti()

print v3.x
print v3.y
print v3.z

wait key

FUNCTION VectorMulti()
   v3.x = (v1.x) * (v2.x)
   v3.y = (v1.y) * (v2.y)
   v3.z = (v1.z) * (v2.z)
ENDFUNCTION

You could also use array/stack feature like IanM's example.

This example uses strings but types will work also. It's very simular to how any compiler passes parameters to a function (Push Data on Stack, Call function, Pop data off Stack). It will also allow you to create functions with variable number of parameters.

+ Code Snippet

dim MyAry(0) as string
MyAry(0) = "Index 0 is here"
array index to stack MyAry()

add to stack MyAry()
MyAry() = "World"
add to stack MyAry()
MyAry() = "Hello "
add to stack MyAry()
MyAry() = "2"

print AddStrings()

print MyAry(0)

undim MyAry(0)
wait key

function AddStrings()
RetVal$ = ""
t = val(MyAry())
remove from stack MyAry()
for x = 1 to t
  RetVal$ = RetVal$ + MyAry()
  remove from stack MyAry()
next x
endfunction RetVal$

Dave...

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indi

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Posted: 11th Jul 2003 08:06

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the above snippet was missing the global statement for it to work

+ Code Snippet

TYPE Vector
global  x AS FLOAT
global  y AS FLOAT
global  z AS FLOAT
ENDTYPE

v1 AS Vector
v2 AS Vector
v3 AS Vector

v1.x = 10
v1.y = 20
v1.z = 30

v2.x = 10
v2.y = 20
v2.z = 30

VectorMulti()

print v3.x
print v3.y
print v3.z

wait key

FUNCTION VectorMulti()
   v3.x = (v1.x) * (v2.x)
   v3.y = (v1.y) * (v2.y)
   v3.z = (v1.z) * (v2.z)
ENDFUNCTION

you can use an array as well, a typed array definition will work as an input parameter to a function, but a simple array wont

http://www.lunarpixel.com
http://www.lunarpixel.com/dt/

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Shadow Robert

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Posted: 11th Jul 2003 08:17

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or with people missing the question altogether could try this...

#constant TRUE   1
#constant FALSE  0

type VECTOR_t
   active as boolean
   pointer as dword
endtype
global dim vectors(256) as VECTOR_t

MakeVector( vector as dword )
   local ptr as dword 
   if vectors(vector).active=TRUE then exitfunction FALSE
   ptr=(vectors(vector).pointer=make memory(12))
   vectors(vector).active=TRUE
endfunction ptr

SetVector( vector as dword, x as float, y as float, z as float )
 local addr as dword
 if vectors(vector).active = FALSE then exitfunction FALSE
 addr = vectors(vector).pointer
 *addr = x : addr=addr+4
 *addr = y : addr=addr+4
 *addr = z
endfunction TRUE

DeleteVector( vector as dword )
   if vectors(vector).active = FALSE then exitfunction FALSE
   delete memory vectors(vector).pointer
   vectors(vector).active=FALSE
endfunction TRUE

GetVectorPtr( vector as dword )
endfunction vectors(vector).pointer

GetVectorNumber( ptr as dword )
   local r as dword
   local i as dword
   for i=1 to 65535
      if vectors(i).pointer=ptr
         r=i
         exitfunction r
      endif
   next i
endfunction FALSE

VectorX( vector as dword )
   local x as float
   local ptr as dword
   ptr=vectors(vector).pointer
   x = *ptr
endfunction x

VectorY( vector as dword )
   local y as float
   local ptr as dword
   ptr=vectors(vector).pointer+4
   y = *ptr
endfunction y

VectorZ( vector as dword )
   local z as float
   local ptr as dword
   ptr=vectors(vector).pointer+8
   z = *ptr
endfunction z

+ Code Snippet

#constant TRUE   1
#constant FALSE  0

type VECTOR_t
   active as boolean
   pointer as dword
endtype
global dim vectors(256) as VECTOR_t

MakeVector( vector as dword )
   local ptr as dword 
   if vectors(vector).active=TRUE then exitfunction FALSE
   ptr=(vectors(vector).pointer=make memory(12))
   vectors(vector).active=TRUE
endfunction ptr

SetVector( vector as dword, x as float, y as float, z as float )
 local addr as dword
 if vectors(vector).active = FALSE then exitfunction FALSE
 addr = vectors(vector).pointer
 *addr = x : addr=addr+4
 *addr = y : addr=addr+4
 *addr = z
endfunction TRUE

DeleteVector( vector as dword )
   if vectors(vector).active = FALSE then exitfunction FALSE
   delete memory vectors(vector).pointer
   vectors(vector).active=FALSE
endfunction TRUE

GetVectorPtr( vector as dword )
endfunction vectors(vector).pointer

GetVectorNumber( ptr as dword )
   local r as dword
   local i as dword
   for i=1 to 65535
      if vectors(i).pointer=ptr
         r=i
         exitfunction r
      endif
   next i
endfunction FALSE

VectorX( vector as dword )
   local x as float
   local ptr as dword
   ptr=vectors(vector).pointer
   x = *ptr
endfunction x

VectorY( vector as dword )
   local y as float
   local ptr as dword
   ptr=vectors(vector).pointer+4
   y = *ptr
endfunction y

VectorZ( vector as dword )
   local z as float
   local ptr as dword
   ptr=vectors(vector).pointer+8
   z = *ptr
endfunction z

you could then use that to have a 3D Vector that works identical to DBP's

you could pass the actual vector into function either by the vector number or by the pointer

and use the pointer to grab the actual data allowing it to be a more open version of the vectoring structures

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swdave

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Posted: 11th Jul 2003 21:10

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The question was....

@pat1926

Quote: "
Is it possible to have a funciton with types as the inputs?
"

No it dont work......

@indi

Quote: "the above snippet was missing the global statement for it to work"

I use patch 4.1 it doesnt require the global, you might be using something else but I will take your advice instead of learn the hard way on the next patch

@Raven

Why dont u get a job?

NASA is looking for programmers to go on the next Mars expedition.

You can still post here but it will just take a bit longer for us to see it

.

Dave...

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DarkBASIC Professional Discussion / Types in Functions??