Re^2: Low-level version of Win32::API::Struct

Thank you, I understand that I'm in the wierd option of 32 bit perl for 64 int, Intel and Windows XP (but perl running through Cygwin). I think your post will be very helpful when I make the simplified example from my previous post work and I move into the original problem.

As a quick refresh, the simplified example from my previous post:

    #### import an API that uses this structure
    my $getCursor = new Win32::API('user32', 'GetCursorPos','S','N');
    
    #### create a 'POINT' object
    $lpPoint=pack('LL',0,0);
    #### call the function passing our structure object
    $getCursor->Call($lpPoint);
    
    #### and now, access its members
    my ($x,$y) = unpack('LL',$pt);
    print "The cursor is at: ".$x.", ".$y."\n";
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No matter which parameter I use within pack ('J','L','N','Q' or 'V') in $lpPoint=pack('LL',0,0); I still get the error "Can't call method Pack on a undefined value". The error pops up in $getCursor->Call($lpPoint);.

From CPAN doc on Win32::API seems that I can substitute the Win32::API::Struct for the packed variable and then pass it to the Win32::API object. Any idea what I'm missing?

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Re^3: Low-level version of Win32::API::Struct by bulk88 (Priest) on Aug 01, 2012 at 17:32 UTC
That is not an example from the docs. `my $getCursor = new Win32::API('user32', 'GetCursorPos','S','N');` [download] should be `my $getCursor = new Win32::API('user32', 'GetCursorPos','P','N');` [download] since $lpPoint is a scalar string formally. 'S'/'T' are only for ::Struct objects. The result of pack() is a scalar string. Not a blessed object. If you had a newer version of ::API, you would get a proper croak message `croak("Win32::API::Call: parameter %d must be +a%s", i+1, " Win32::API::Struct object!\n");` [download] much better than 0.68 blindly doing ->Pack() on whatever scalar happens to fall in as argument which is what is happening in your case.	[reply] [d/l] [select]

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Re^3: Low-level version of Win32::API::Struct
by bulk88 (Priest) on Aug 01, 2012 at 17:32 UTC

    my $getCursor = new Win32::API('user32', 'GetCursorPos','S','N');
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    my $getCursor = new Win32::API('user32', 'GetCursorPos','P','N');
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                        croak("Win32::API::Call: parameter %d must be 
+a%s",  i+1, " Win32::API::Struct object!\n");
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