[fpc-devel]SizeOf() reports 0 for Var Paramaters. (1.1)

Marco van de Voort marcov at stack.nl
Sun Jul 27 23:34:30 CEST 2003

> O_o Woah.. Weird.  Ok.. I thought it worked.. but mabey not.  1.0.6 seems
> to return 4 for SizeOf() a var param.  While 1.1 returns 0.

It can't work, simply because it is impossible for the procedure
to get the size of such a parameter (incl the const variant).
The compiler can't know it when compiling (several routines could
call this routine with different sizes), and there is no runtime
info passed. 

In general:

procedure dotest (var a);  // const case is the same
 -> only pointer to "a" is passed. No way to determine type, number
	of elements or #bytes.

procedure dotest (var a: array of longint);
-> pointer + number of elements  is passed.

procedure dotect (const a: array of const); // delphi construct
-> 1. a tabel with a pointer and a typecode for each item is 
	created on the stack
   2. a pointer to that item+ number of items is pushed onto the stack

The last one needs to be called like


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