Low Level API

The simplest way to use CmdLine unit is to create a callback function that will be called for each parameter of the command line.

 1 (*demo1.pas*)
 2 program Demo1;
 3 {$mode objfpc}{$h+}
 4 uses
 5   Classes, SysUtils, CmdLine;
 6
 7 procedure Handler(Kind: TOptionKind; const Option, Value: String);
 8 begin
 9   case Kind of
10   okShort:        WriteLn('opt: -', Option);
11   okLong:         WriteLn('opt: --', Option);
12   okShortWithVal: WriteLn('opt: -', Option, '=', Value);
13   okLongWithVal:  WriteLn('opt: --', Option, '=', Value);
14   okArgument:     WriteLn('arg: ', Value);
15   end;
16 end;
17
18 begin
19   SetCallback(@Handler);
20   InitializeCommandLineScan;
21   ScanCommandLine;
22   FinalizeCommandLineScan;
23 end.

Lines 7-16: Here is the callback function that will be called for each parameter of the command line. It receives the parameters of the command line already identified (Kind) and cut into option (Option) and value (Value).

Line 19: Here we set the callback function.

Line 20: Prepare for scanning.

Line 21: Do command line scanning.

Trying this program you’ll get something like:

------------------------------------------------------------------------------
~$ ./demo_1 -a --long-a -b=45 --long-b=78 arg1 arg2 arg3 -- -s --long-s
opt: -a
opt: --long-a
opt: -b=45
opt: --long-b=78
arg: arg1
arg: arg2
arg: arg3
arg: -s
arg: --long-s
------------------------------------------------------------------------------

You can see that :

• An option containing an equal sign is splitted in two parts : the option and a value.
• Everything after "--" is seen as simple arguments.