[tcltk-perl] scalar($w->getOpenFile)

[Gisle A. <gi...@Ac...>]

Gisle Aas <gi...@Ac...> writes:

> To me it wrong if:
> 
>     $tcl->Eval("set var {a b c}");
> 
> returns something different to perl than
> 
>     $tcl->Eval("set var [list a b c]");
> 
> if these two expressions have exactly the same semantics in Tcl.
> 
> I would suggest that we always return the string in scalar context and
> always list in list context.  If the value is not a valid list, then
> we croak in list context.

If you try the following program:

    #!/usr/bin/perl -w
    
    use Tcl::Tk qw(:perlTk);
    
    my $mw = MainWindow->new;
    my $label = $mw->Label(-text => "Hello")->pack;
    if (my $file = $mw->getOpenFile) {
        $label->configure(-text => "File [$file]");
        $mw->after(5000, sub { $mw->destroy });
    }
    
    MainLoop;

and then hit "Cancel" to the dialog that pops up, then we fill in the
field with something like "File [ARRAY(0x8141ad8)]".  Apparently
tk_getOpenFile returns a list instead of string, but this is not
documented.  Since there is no semantic difference between a list and
a string this does not really matter to Tcl, but for perl with the
current Tcl.pm behaviour it does.  I think we should make $tcl->Eval
and $tcl->call behave as I describe in the quoted text above.  That
would fix this problem and in general make things sane.

Is there a way to make an automatic test case out of this?  I guess
I'm asking if there is a way to make the program above hit the
"Cancel" button by itself.

In our private branch I have used this workaround for now:

--- Tcl-Tk/lib/Tcl/Tk.pm.~1~	Wed Apr 21 05:43:50 2004
+++ Tcl-Tk/lib/Tcl/Tk.pm	Wed Apr 21 05:43:50 2004
@@ -839,19 +839,25 @@
     my $self = shift;
     my %args = @_;
     $args{'-parent'} = $self->path unless defined $args{'-parent'};
-    $wint{$$self}->call('tk_getOpenFile', %args);
+    my @files = $wint{$$self}->call('tk_getOpenFile', %args);
+    return $files[0] unless wantarray;
+    return @files;
 }
 sub getSaveFile {
     my $self = shift;
     my %args = @_;
     $args{'-parent'} = $self->path unless defined $args{'-parent'};
-    $wint{$$self}->call('tk_getSaveFile', %args);
+    my @files = $wint{$$self}->call('tk_getSaveFile', %args);
+    return $files[0] unless wantarray;
+    return @files;
 }
 sub chooseDirectory {
     my $self = shift;
     my %args = @_;
     $args{'-parent'} = $self->path unless defined $args{'-parent'};
-    $wint{$$self}->call('tk_chooseDirectory', %args);
+    my @files = $wint{$$self}->call('tk_chooseDirectory', %args);
+    return $files[0] unless wantarray;
+    return @files;
 }
 sub messageBox {
     my $self = shift;
End of Patch.

> Alternatively we return return some object that just wraps the Tcl_Obj
> and can used as both a string and array reference.  This can be
> combined with the previous alternative, so this only happens in scalar
> context.
> 
> Alternatively we have a separate methods that indicate if a string,
> array reference or list is wanted as return value.
> 
>    $tcl->Eval_giving_string($code);
>    $tcl->Eval_giving_arrayref($code);
>    $tcl->Eval_giving_list($code);