Filtering File Selectors

MET — Sat, 17 Jan 2009 17:54:27 +0000

Why is it that almost every language/framework offers totally different, and yet similar, solutions for filtering in/out files from selection menus?

.NET

OpenFileDialog dialog = new OpenFileDialog();
dialog.Filter = "Text files (*.txt)|*.txt|All files (*.*)|*.*"

In the example there are two types of selectors: text files (.txt); all files (*.*). Labels (Text files) are separated from their filter values (*.txt) by the pipe character and each filter type is separated by… a pipe too! It looks weird, but considering it’s based off old-school Windows API I can understand and sort of respect their desire to not change. MFC sucks and using weird DSLs instead of creating more objects can have it’s benefits.

Flash

var filters:Array = new Array();
filters.push(new FileFilter('Text Files', '*.txt'));
filters.push(new FileFilter('Rich Text', '*.rtf'));

var file:flash.net.FileReference = new FileReference();
file.browse(filters);

FileFilter is constructed with the rules like so: FileFilter(‘Text Files’, ‘*.txt’). You can either specify multiple FileFilters or append multiple rulsets to the same label like so: FileFilter(‘Text files’, ‘*.txt;*.txt2′). Truly a cleaner interface than .NET’s, but many could argue it’s Object over kill (AWT/SWING is probably worse).

Gtk+

GtkFileFilter *file_filter = gtk_file_filter_new();
gtk_file_filter_set_name(file_filter, "Log Files (*.bab)");
gtk_file_filter_add_pattern(file_filter, "*.bab");

Even though Gtk+ is in C, it has a nice interface (which many languages like Flash could be accused of robbing). The name is different than the pattern, and there aren’t ugly crazy separators like in .NET/MFC.

Swing

ExampleFileFilter filter = new ExampleFileFilter();
filter.addExtension("jpg");
filter.addExtension("gif");
filter.setDescription("JPG &amp;amp; GIF Images");

JFileChooser dialog = new JFileChooser();
dialog.setFileFilter(filter);

This isn’t too bad until you realize that ExampleFileFilter is a custom class which extends abstract FileFilter. Yes there are other ways, but boy is this annoying!

Python (Gtk+)

        dialog = gtk.FileChooserDialog(title="Select the World"
                            , action=gtk.FILE_CHOOSER_ACTION_OPEN
                            , buttons=(gtk.STOCK_CANCEL
                                                    , gtk.RESPONSE_CANCEL
                                                    , gtk.STOCK_OPEN
                                                    , gtk.RESPONSE_OK))
        filter = gtk.FileFilter()
        filter.set_name("All files")
        filter.add_pattern("*")
        dialog.add_filter(filter)

Just like Gtk+ but with the Python-esk feel.

Conclusion

I must be stating the obvious: Framework developers hate programmers.

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