On Mar 20, 2009, at 10:28 AM, Brian Stevens wrote:

>
> On Mar 19, 2009, at 8:49 PM, Max Taylor wrote:
>>>
>>> In FBtoC, '=' is a synonym for '#' when either appears in front  
>>> of a function argument. They both mean "evaluate the argument as  
>>> an expression and pass its value, even if the called function's  
>>> declaration would otherwise require the address of a variable to  
>>> be obtained and passed".
>
> One situation where this occurs is passing pointers ( say to a  
> record structure )  to functions. Within the called function that  
> receives the pointer, it might call another function that also  
> requires a pointer to that same record structure. This second call  
> would use a '#' before the record structure name to pass it "as  
> is". Without the '#' an attempt would be made to generate the  
> address to the record but this would be wrong because it already  
> contains a pointer to the record.
>
>
>
> local fn ProcessIt ( aRecPtr as ^someRec )
> end fn
>
>
> local fn test ( theRecPtr as ^someRec )
>
> fn ProcessIt( #someRec ) // receiver wants pointer to record, so  
> pass as is since it is already a pointer.
>
> end fn
>
> dim as someRec   myRec
>
> fn test ( @myRec )
>
>
>
> Brian S

That confuses me as written.

I was under the impression, and with functioning code to support it,   
that if you pass a pointer to a function expecting a pointer param,  
and then send it along to another function expecting a pointer to the  
same record -type-, you are fine to just pass along again the pointer  
from the function, and don't need the #, since the param defines the  
pointer as a pointer to the something?

I know that some toolbox calls do not like an incoming Local Fn   
pointer param on occasion, and in that case, you need to add the  
handy = or #, which in effect, sends them the goods, rather than the  
address of the goods.

Robert

Local Fn HannibalRector(r as ^rect)
print r.right
end fn

Local Fn RectMyBankAccount(r as ^rect)
Fn HannibalRector(r)
end fn

dim r as rect
setRect(r,0,0,32,32)

window 1

Fn RectMyBankAccount(@r) // (don't even have to add the @ usually)
do
handleEvents
until gFBQuit


//same with a record...


begin globals
Begin record SomeRec
dim r as rect
dim u as int
dim sure as long
end record
end globals

Local Fn HannibalRector(r as ^SomeRec)
print r.r.right // you see 32.
end fn

Local Fn RectMyBankAccount(r as ^SomeRec)
Fn HannibalRector(r)
end fn

dim r as SomeRec
setRect(r.r,0,0,32,32)
window 1
Fn RectMyBankAccount(@r) // (don't even have to add the @ usually)

do
handleEvents
until gFBQuit