WInput widget: notify owner about changes

[andrew_b]

WInput widget should notify it's owner about changes. At least, WInput's owner should know when WInput becomes empty or not empty.

[andrew_b]

(In #3593) State changed to "on hold" until #3597 will be implemented.

[andrew_b]

Branch: 3597_winput_notify
changeset:d945ccdd1f53f07fcd645e83459f851b060a4971

This changeset can de tested in 3593_find_file_empty_name.

[mooffie]

This patch makes the notification fire even on keys that don't modify the contents (e.g., on movement keys). This is insignificant for the current need (turning on/off dependent checkboxes) but for tasks that aren't executed "instantly" this might be a concern.

(The reason I care about this isn't nitpicking. In mc² I use this UI pattern (of triggering some action when WInput changes) in the following modules: visual rename, recently visited files, calculator, find as you type, filter as you type. It happens that computers are fast and users won't notice anything amiss if movement keys trigger spurious actions but this would bother me, as a programmer, still.)

I don't think it's too hard to fix this: input_execute_cmd() has 3 switch statements. We can split the middle one into two: commands that modify the buffer and those that don't. For those that do, we set a 'modified' flag. We shouldn't mind having false positives (the documentation for 'modified' should say so). (The alternative is to keep a copy of the original buffer and compare the contents.)

Otherwise why bother? Instead of implementing a half-cooked notification, the dialog can respond to MSG_POST_KEY; something along of:

cb_ret_t my_dialog_callback(w, ...)
{
    ...
    case MSG_POST_KEY:
        if (DIALOG (w)->current->data == the_input_box)
            /* the text has possibly changed. */
            do_something();  
    ...
}

[mooffie]

(BTW, I haven't forgotten my responsibility for #3566. I'm working on it.)

[andrew_b]

Replying to mooffie:

Instead of implementing a half-cooked notification, the dialog can respond to MSG_POST_KEY

Indeed. I like this idea. Thanks! I'll implement this for #3593, #3594.

I'd like to close this ticket as wontfix in favour of #3566.

[mooffie]

Replying to andrew_b:

Replying to mooffie:

Instead of implementing a half-cooked notification, the dialog can respond to MSG_POST_KEY

Indeed. I like this idea. Thanks! I'll implement this for #3593, #3594.

I'd like to close this ticket as wontfix in favour of #3566.

Sure, close it.