[Info-vax] Local Versus Global Command Options

[Arne Vajhøj]

On 2/14/2025 8:38 AM, Simon Clubley wrote:
> On 2025-02-13, Lawrence D'Oliveiro <ldo at nz.invalid> wrote:
>> What would DCL-style syntax for ffmpeg look like? I suppose one
>> obvious equivalence would be
>>
>>      ffmpeg -
>>          «infile-1»/«local-input-options-1»,«infile-2»/«local-input-options-2»,... -
>>          «outfile-1»/«local-output-options-1»,«outfile-2»/«local-output-options-2»,... -
>>
>> (being very careful about where the commas go), but what about the
>> syntax for filtergraphs? Would it be something like
>>
>>      /vf=(«filter-name-1»=«filter-params-1»,«filter-name-2»=«filter-params-2»...)
>>
>> Does DCL have provision for this sort of complexity?
> 
> Not in any meaningful way. There's no way to validate the syntax or
> parameters of a filter or other ffmpeg syntax with DCL. For a simple
> example, when merging two files, one with an audio stream and one with
> a video stream, into a MP4 output container then specifying the input and
> output video stream numbers would be a parameter along the lines of "0:v:0".
> 
> How would you even specify in DCL the first and last fields are numbers
> and the middle field is a letter from a list of valid values ?
> 
> You can use DCL syntax in the way you specify, but the vast majority
> of the parsing would still have to be done in ffmpeg as it is at the
> moment. DCL syntax doesn't really give you anything extra.

You can define a bit in CLD. Including specifying that
something is a number and something else is from an
enumeration list.

$ type fun3.cld
define verb fun3
     image "sys$disk:[]fun3"
     parameter p1, value(type=$file, list, required)
qualifier q, value(type=threeitems, list, required), placement=local
define type threeitems
     keyword a, value(type=$number, required)
     keyword b, value(type=$quoted_string, required)
     keyword c, value(type=myenum, required)
define type myenum
     keyword x
     keyword y
     keyword z
$ type fun3.pas
[inherit('sys$library:pascal$cli_routines')]
program fun3(input,output);

type
    pstr = varying [255] of char;

var
    fnm, a, b, c : pstr;

begin
    while odd(cli$get_value('P1', fnm.body, fnm.length)) do begin
       write(fnm);
       if odd(cli$present('Q')) then begin
          cli$get_value('Q.A', a.body, a.length);
          write(' A=', a);
          cli$get_value('Q.B', b.body, b.length);
          write(' B=', b);
          cli$get_value('Q.C', c.body, c.length);
          write(' C=', c);
       end;
       writeln;
    end;
end.
$ pas fun3
$ lin fun3
$ set comm fun3
$ fun3 x.dat/q=(a:1,b:"This is x",c:x), y.dat/q=(a:2,b:"This is y",c:y), 
z.dat/q=(a:3,b:"This is z",c:z)
x.dat A=1 B="This is x" C=X
y.dat A=2 B="This is y" C=Y
z.dat A=3 B="This is z" C=Z
$ on error then continue
$ fun3 x.dat/q=(a:x,b:"This is x",c:x), y.dat/q=(a:2,b:"This is y",c:y), 
z.dat/q=(a:3,b:"This is z",c:z)
%DCL-W-NUMBER, invalid numeric value - supply an integer
  \X\
$ fun3 x.dat/q=(a:1,b:"This is x",c:xdat), y.dat/q=(a:2,b:"This is 
y",c:y), z.dat/q=(a:3,b:"This is z",c:z)
%DCL-W-IVKEYW, unrecognized keyword - check validity and spelling
  \XDAT\

Arne