+=item _store_value()
+
+parses a complex var name, and stores it in the form.
+
+syntax:
+ $form->_store_value($key, $value);
+
+keys must start with a string, and can contain various tokens.
+supported key structures are:
+
+1. simple access
+ simple key strings work as expected
+
+ id => $form->{id}
+
+2. hash access.
+ separating two keys by a dot (.) will result in a hash lookup for the inner value
+ this is similar to the behaviour of java and templating mechanisms.
+
+ filter.description => $form->{filter}->{description}
+
+3. array+hashref access
+
+ adding brackets ([]) before the dot will cause the next hash to be put into an array.
+ using [+] instead of [] will force a new array index. this is useful for recurring
+ data structures like part lists. put a [+] into the first varname, and use [] on the
+ following ones.
+
+ repeating these names in your template:
+
+ invoice.items[+].id
+ invoice.items[].parts_id
+
+ will result in:
+
+ $form->{invoice}->{items}->[
+ {
+ id => ...
+ parts_id => ...
+ },
+ {
+ id => ...
+ parts_id => ...
+ }
+ ...
+ ]
+
+4. arrays
+
+ using brackets at the end of a name will result in a pure array to be created.
+ note that you mustn't use [+], which is reserved for array+hash access and will
+ result in undefined behaviour in array context.
+
+ filter.status[] => $form->{status}->[ val1, val2, ... ]
+
+=cut