How to convert from C #define with functions

Question

I have C header with defines like

#define tds_accept      accept
#define tds_getpeername getpeername
#define tds_getsockopt  getsockopt
#define tds_getsockname getsockname
#define tds_recvfrom    recvfrom

where I should convert defines to Delphi and assign functions (from Winsock2). I tried both const and type

type
  tds_accept      = accept;
  tds_getpeername = getpeername;
  tds_getsockopt  = getsockopt;
  tds_getsockname = getsockname;
  tds_recvfrom    = recvfrom;

and have errors E2007 Constant or type identifier expected or E2035 Not enough actual parameters
Is it possible to do it with Delphi?

AFAIR delphi has no macros support, you can either go with pointers to functions or external macro processor: stackoverflow.com/questions/1893989/… — Iłya Bursov
– Iłya Bursov, Commented Nov 1, 2013 at 17:35

Jerry Dodge · Accepted Answer · 2013-11-01 18:11:13Z

Use typed variables instead, eg:

var
  tds_accept      : function(s: TSocket; addr: PSockAddr; addrlen: PInteger): TSocket; stdcall;
  tds_getpeername : function(s: TSocket; var name: TSockAddr; var namelen: Integer): Integer; stdcall;
  tds_getsockopt  : function(s: TSocket; level, optname: Integer; optval: PAnsiChar; var optlen: Integer): Integer; stdcall;
  tds_getsockname : function(s: TSocket; var name: TSockAddr; var namelen: Integer): Integer; stdcall;
  tds_recvfrom    : function(s: TSocket; var Buf; len, flags: Integer; var from: TSockAddr; var fromlen: Integer): Integer; stdcall;

initialization
  tds_accept      := accept;
  tds_getpeername := getpeername;
  tds_getsockopt  := getsockopt;
  tds_getsockname := getsockname;
  tds_recvfrom    := recvfrom;

Or:

type
  lpfn_accept      = function(s: TSocket; addr: PSockAddr; addrlen: PInteger): TSocket; stdcall;
  lpfn_getpeername = function(s: TSocket; var name: TSockAddr; var namelen: Integer): Integer; stdcall;
  lpfn_getsockopt  = function(s: TSocket; level, optname: Integer; optval: PAnsiChar; var optlen: Integer): Integer; stdcall;
  lpfn_getsockname = function(s: TSocket; var name: TSockAddr; var namelen: Integer): Integer; stdcall;
  lpfn_recvfrom    = function(s: TSocket; var Buf; len, flags: Integer; var from: TSockAddr; var fromlen: Integer): Integer; stdcall;

var
  tds_accept      : lpfn_accept       = accept;
  tds_getpeername : lpfn_getpeername  = getpeername;
  tds_getsockopt  : lpfn_getsockopt   = getsockopt;
  tds_getsockname : lpfn_getsockname  = getsockname;
  tds_recvfrom    : lpfn_recvfrom     = recvfrom;

David Heffernan · Accepted Answer · 2013-11-01 18:49:28Z

0

Delphi does not have a pre-processor. So you typically find different ways to solve problems that are handled in C/C++ with the pre-processor. Personally, I think I'd use load time linking like this:

function tds_accept(...): TSocket; external dllname name 'accept';

and so on.

answered Nov 1, 2013 at 18:49

David Heffernan

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