hasen wrote:
How to pass it to C functions that expect a non-null string?
Specifically to GTK+ (using gtkD)
I also asked this on stackoverflow
http://stackoverflow.com/questions/931360/
------------
Using D1 with phobos
I have a text entry field, instance of gtk.Entry.Entry,
calling setText("") raises a run time error
Gtk-CRITICAL **: gtk_entry_set_text: assertion `text != NULL' failed
Why? It seems to be a problem with D, I tried this:
string empty = "";
assert (empty != null);
my_entry.setText(empty)
The program terminated as the assertion failed.
How can I work around this?
This is one of those D quirks that trip people up quite frequently. When
testing a string for null using the regular ==/!= operators, an empty
string will always result the same as a null string. To truly test for
null, use the is/!is operators instead. This will not take the contents
of the string into account. The following will do what you expect:
string empty = "";
assert(empty !is null);
my_entry.setText(empty);
And since strings, like all arrays, are structs with the length and ptr
fields, you can also do either of the following:
assert(empty.ptr != null);
assert(empty.ptr !is null);
