[Gambas-user] Using EXEC

[Benoît Minisini]

> EXEC is a wonderful thing, lighter than SHELL, but it needs things
> passed as elements of a string array and that is making for some ugly code.
> 
> Say for example you want to play two videos as a playlist in VLC, in
> exec the command might look like this;
> 
> EXEC["vlc","--intf","rc", "Video1.avi","Video2.avi"]
> 
> But what if you had different quantities of videos to play, lets say
> next time you needed to play 4 videos? How would you use EXEC to do this?
> 
> 
> I thought of building the string and embedding the quotes in it like this;
> 
> ExecString = chr$(34)& "vlc" & chr$(34) & "," & chr$(34) & "--intf" &
> chr$(34) & "," & chr$(34) & "rc"& chr$(34) & ","
> For X= 0 TO sFile.Count - 1
>        ExecString = ExecString & chr$934) & sFile[X] & chr$(34)
>        IF X < sFile.Count -1 then
>           ExecString = ExecString & ","
>       End IF
> NEXT
> 
> Which would result in a string that looks like this;
> 
> "vlc", "--intf", "rc", "video1.avi", "video2.avi"
> 
> Nope. It sees the one string as one element when what I want is the
> contents of the string to be inserted as multiple elements.
> 
> At the moment I am fetching the video file names from a directory
> listing, splitting that up into an array, then checking the number of
> elements in the array and using a case statement to do the work...
> 
> SELECT CASE sFile.Count
>            CASE 1
>                 mpProcessHandle = EXEC ["vlc", "--intf", "rc", sFile[0]]
> FOR INPUT OUTPUT AS "VLC"
>            CASE 2
>                 mpProcessHandle = EXEC ["vlc", "--intf", "rc", sFile[0],
> sFile[1]] FOR INPUT OUTPUT AS "VLC"
>            CASE 3
>                 mpProcessHandle = EXEC ["vlc", "--intf", "rc", sFile[0],
> sFile[1], sFile[2]] FOR INPUT OUTPUT AS "VLC"
>            CASE 4
>                 mpProcessHandle = EXEC ["vlc", "--intf", "rc", sFile[0],
> sFile[1], sFile[2]] FOR INPUT OUTPUT AS "VLC"
> END SELECT
> 
> It ain't pretty. "sFile" is a string array derived from another string
> that contains the names of videos which in my case are delimited by
> spaces. Definetly the brute-force/bulldozer approach, big, ugly, and
> cumbersome, but it does work. Does anyone else know of a more elegant
> solution?
> 
> Regards
> Steve.
> 

[ ... ] is not a compiler thing, but an operator that build an array at 
runtime.

So you can make the EXEC array with "New String[]" and populate it as you 
need:

  Dim aFile As String[] ' The files to open
  Dim aArg As String[]

  aArg = ["vlc", "--intf", "rc"]
  aArg.Insert(aFile)
  Exec aArg For Input Output As "VLC"

Regards,

-- 
Benoît Minisini