I have a static 2 dimensional array of objects in a Kotlin project:
class Tables {
companion object{
lateinit var finalTable: Array<Array<Any?>?>
}
}
It is a little clearer in Java:
public class Tables {
public static Object[][] finalTable;
}
The third element in one row of objects in the table, is a string boxed as an object. In other words: finalTable[*][2] is a string describing the item. When I add an item to the array in Kotlin, I want to sort the entire array in alphabetical order of the description.
In Java this is easy:
Arrays.sort(Tables.finalTable, Comparator.comparing(o -> (String) o[2]));
When I try to use Android Studio to translate the Java code into Kotlin, it produces the following:
Arrays.sort( Tables.finalTable, Comparator.comparing( Function { o: Array<Any?>? -> o[2] as String }) )
This does not work, you have change the String cast as follows:
Arrays.sort( Tables.finalTable, Comparator.comparing( Function { o: Array<Any?>? -> o[2].toString() }) )
This version will compile and run, but it totally messes up the sorting of the table, so it does not work. I have tried variations on this theme, without any success. To get my project to work, I had to create a Java class in the Kotlin project with the functional Java code listed above:
public class ArraySort {
public void sortArray(){
Arrays.sort(Tables.finalTable, Comparator.comparing(o -> (String) o[2]));
}
}
This sorts the table like a charm, but I would prefer to keep my project "pure Kotlin". Can anyone suggest a pure Kotlin method to sort such an array? Thanks!
Unless I'm missing something, you can just do this:
Tables.finalTable.sortBy { it[2] as String }
which sorts your array in place. sortedBy will produce a new copy of the original if that's what you want instead, and might be why the comment suggestions weren't working for you.
But this whole unstructured array situation isn't ideal, the solution is brittle because it would be easy to put the wrong type in that position for a row, or have a row without enough elements, etc. Creating a data structure (e.g. a data class) would allow you to have named parameters you can refer to (making the whole thing safer and more readable) and give you type checking too
could you please help me.
1) Is it better to keep orders in the EA's arrays rather than querying the system with the Order.. commands in mql4? Keeping data in arrays means that you have to query the system less and that internet reliability may be less of an issue. However, the coding required to keep an accurate order book is quite cumbersome.
2) How do you keep track of orders that is on the same Symbol but has come from two different EA's?
Thank you very much
It depends on your needs and ideas, without that it could be quite difficult to tell anything.
you can keep an array of ticket numbers (or CArrayObj) but need to check that ticket exists before doing other operations (like trail). if you have problems with internet - change vps and do not try to solve it with coding.
Each ea keeps a book of its own deals.
Cannot imagine sence of keeping just numbers of tickets, but maybe it exists. If you need to store some data in addition to what can be achieved from Order...() then use classes or structures, some fields might be filled with osl,tp,oop,lot,magic, symbol etc once and do not call Order.() functions later except OrderProfit(),OrderClosePrice() and OrderCloseTime()-such functions would be called all the time.
Example of how to store data is below: instances of CTrade are added to CArrayObj
#include <Object.mqh>
#include <Arrays\ArrayObj.mqh>
class CTrade : public CObject
{
private:
int m_ticketId;
double m_oop,m_osl,m_otp,m_lot;//OrderOpenPrice() and sl, tp, lot-add more
public:
CTrade(const int ticket){
m_ticketId=ticket;
}
bool isTicketExist(){
if(OrderSelect(m_ticketId,SELECT_BY_TICKET))
return(OrderCloseTime()==0);
else return(false);//or GetLastError()!=4108
}
};
CArrayObj* listOfTrades=NULL;
int OnInit(void){
listOfTrades=new CArrayObj;
}
void OnDeinit(const int reason){
if(CheckPointer(listOfTrades)==POINTER_DYNAMIC)
delete(listOfTrades);
}
void OnTick(){
for(int i=listOfTrades.Total()-1;i>=0;i--){
CTrade *trade=listOfTrades.At(i);
if(!trade.isTicketExist())
{listOfTrades.Delete(i);continue;}
//do trail or what you need
} // - loop over the array when necessary but clean it first
}
listOfTrades.Add(new CTrade(ticket));// - way to add elements to the list
How can I customize the completion of a GtkComboBoxText with both a "static" aspect and a "dynamic" one? The static aspect is because some entries are known and added to the combo-box-text at construction time with gtk_combo_box_text_append_text. The dynamic aspect is because I also need to complete thru some callback function(s), that is to complete dynamically -after creation of the GtkComboBoxText widget- once several characters has been typed.
My application uses Boehm's GC (except for GTK objects of course) like Guile or SCM or Bigloo are doing. It can be seen as an experimental persistent dynamic-typed programming language implementation with an integrated editor coded on and for Debian/Linux/x86-64 with the system GTK3.21 library, it is coded in C99 (some of which is generated) and is compiled with GCC6.
(I don't care about non-Linux systems, GTK3 libraries older than GTK3.20, GCC compiler older that GCC6)
question details
I'm entering (inputting into the GtkComboBoxText) either a name, or an object-id.
The name is C-identifier-like but starts with a letter and cannot end with an underscore. For example, comment, if, the_GUI, the_system, payload_json, or x1 are valid names (but _a0bcd or foobar_ are invalid names, because they start or end with an underscore). I currently have a big dozen of names, but I could have a few thousands of them. So it would be reasonable to offer a completion once only a single or perhaps two letters has been typed, and completion for names can happen statically because they are not many of them (so I feel reasonable to call gtk_combo_box_append_text for each name).
The object-id starts with an underscore followed by a digit and has exactly 18 alphanumeric (sort-of random) characters. For example, _5Hf0fFKvRVa71ZPM0, _8261sbF1f9ohzu2Iu, _0BV96V94PJIn9si1K are possible object-ids. Actually it is 96 almost random bits (probably only 294 are possible). The object-id plays the role of UUIDs (in the sense that it is assumed to be world-wide unique for distinct objects) but has a C friendly syntax. I currently have a few dozen of objects-ids, but I could have a few hundred of thousands (or maybe a million) of them. But given a prefix of four characters like _6S3 or _22z, I am assuming that only a reasonable number (probably at most a dozen, and surely no more than a thousand) object-ids exist in my application with that prefix. Of course it would be unreasonable to register (statically) a priori all the object ids (the completion has to happen after four characters have been typed, and should happen dynamically).
So I want a completion that works both on names (e.g. typing one letter perhaps followed by another alphanum character should be enough to propose a completion of at most a hundred choices), and on object-ids (typing four characters like _826 should be enough to trigger a completion of probably at most a few dozen choices, perhaps a thousand ones if unlucky).
Hence typing the three keys p a tab would offer completion with a few names like payload_json or payload_vectval etc... and typing the five keys _ 5 H f tab would offer completion with very few object-ids, notably _5Hf0fFKvRVa71ZPM0
sample incomplete code
So far I coded the following:
static GtkWidget *
mom_objectentry (void)
{
GtkWidget *obent = gtk_combo_box_text_new_with_entry ();
gtk_widget_set_size_request (obent, 30, 10);
mo_value_t namsetv = mo_named_objects_set ();
I have Boehm-garbage-collected values, and mo_value_t is a pointer to any of them. Values can be tagged integers, pointers to strings, objects, or tuples or sets of objects. So namesetv now contains the set of named objects (probably less than a few thousand of named objects).
int nbnam = mo_set_size (namsetv);
MOM_ASSERTPRINTF (nbnam > 0, "bad nbnam");
mo_value_t *namarr = mom_gc_alloc (nbnam * sizeof (mo_value_t));
int cntnam = 0;
for (int ix = 0; ix < nbnam; ix++)
{
mo_objref_t curobr = mo_set_nth (namsetv, ix);
mo_value_t curnamv = mo_objref_namev (curobr);
if (mo_dyncast_string (curnamv))
namarr[cntnam++] = curnamv;
}
qsort (namarr, cntnam, sizeof (mo_value_t), mom_obname_cmp);
for (int ix = 0; ix < cntnam; ix++)
gtk_combo_box_text_append_text (GTK_COMBO_BOX_TEXT (obent),
mo_string_cstr (namarr[ix]));
at this point I have sorted all the (few thousands at most) names and added "statically" them using gtk_combo_box_text_append_text.
GtkWidget *combtextent = gtk_bin_get_child (GTK_BIN (obent));
MOM_ASSERTPRINTF (GTK_IS_ENTRY (combtextent), "bad combtextent");
MOM_ASSERTPRINTF (gtk_entry_get_completion (GTK_ENTRY (combtextent)) ==
NULL, "got completion in combtextent");
I noticed with a bit of surprise that gtk_entry_get_completion (GTK_ENTRY (combtextent)) is null.
But I am stuck here. I am thinking of:
Having some mom_set_complete_objectid(const char*prefix) which given a prefix like "_47n" of at least four characters would return a garbage collected mo_value_t representing the set of objects with that prefix. This is very easy to code for me, and is nearly done.
Make my own local GtkEntryCompletion* mycompl = ..., which would complete like I want. Then I would put it in the text entry combtextent of my gtk-combo-box-text using gtk_entry_set_completion(GTK_ENTRY(combtextent), mycompl);
Should it use the entries added with gtk_combo_box_text_append_text for the "static" name completion role? How should I dynamically complete using the dynamic set value returned from my mom_set_complete_objectid; given some object-pointer obr and some char bufid[20]; I am easily and quickly able to fill it with the object-id of that object obr with mo_cstring_from_hi_lo_ids(bufid, obr->mo_ob_hid, obr->mo_ob_loid)..
I don't know how to code the above. For reference, I am now just returning the combo-box-text:
// if the entered text starts with a letter, I want it to be
// completed with the appended text above if the entered text starts
// with an undersore, then a digit, then two alphanum (like _0BV or
// _6S3 for example), I want to call a completion function.
#warning objectentry: what should I code here?
return obent;
} /* end mom_objectentry */
Is my approach the right one?
The mom_objectentry function above is used to fill modal dialogs with short lifetime.
I am favoring simple code over efficiency. Actually, my code is temporary (I'm hoping to bootstrap my language, and generate all its C code!) and in practice I'll probably have only a few hundred names and at most a few dozen of thousands of object-ids. So performance is not very important, but simplicity of coding (some conceptually "throw away" code) is more important.
I don't want (if possible) to add my own GTK classes. I prefer using existing GTK classes and widgets, customizing them with GTK signals and callbacks.
context
My application is an experimental persistent programming language and implementation with a near Scheme or Python (or JavaScript, ignoring the prototype aspect, ...) semantics but with a widely different (not yet implemented in september 7th, 2016) syntax (to be shown & input in GTK widgets), using the Boehm garbage collector for values (including objects, sets, tuples, strings...)... Values (including objects) are generally persistent (except the GTK related data : the application starts with a nearly empty window). The entire language heap is persisted in JSON-like syntax in some Sqlite "database" (generated at application exit) dumped into _momstate.sql which is re-loaded at application startup. Object-ids are useful to show object references to the user in GTK widgets, for persistence, and to generate C code related to the objects (e.g. the object of id _76f7e2VcL8IJC1hq6 could be related to a mo_76f7e2VcL8IJC1hq6 identifier in some generated C code; this is partly why I have my object-id format instead of using UUIDs).
PS. My C code is GPLv3 free software and available on github. It is the MELT monitor, branch expjs, commit e2b3b99ef66394...
NB: The objects mentioned here are implicitly my language objects, not GTK objects. The all have a unique object-id, and some but not most of them are named.
I will not show exact code on how to do it because I never did GTK & C only GTK & Python, but it should be fine as the functions in C and Python functions can easily be translated.
OP's approach is actually the right one, so I will try to fill in the gaps. As the amount of static options is limited probably won't change to much it indeed makes sense to add them using gtk_combo_box_text_append which will add them to the internal model of the GtkComboBoxText.
Thats covers the static part, for the dynamic part it would be perfect if we could just store this static model and replace it with a temporay model using gtk_combo_box_set_model() when a _ was found at the start of the string. But we shouldn't do this as the documentation says:
You should not call gtk_combo_box_set_model() or attempt to pack more cells into this combo box via its GtkCellLayout interface.
So we need to work around this, one way of doing this is by adding a GtkEntryCompletion to the entry of the GtkComboBoxText. This will make the entry attempt to complete the current string based on its current model. As an added bonus it can also add all the character all options have in common like this:
As we don't want to load all the dynamic options before hand I think the best approach will be to connect a changed listener to the GtkEntry, this way we can load the dynamic options when we have a underscore and some characters.
As the GtkEntryCompletion uses a GtkListStore internally, we can reuse part of the code Nominal Animal provided in his answer. The main difference being: the connect is done on the GtkEntry and the replacing of GtkComboText with GtkEntryCompletion inside the populator. Then everything should be fine, I wish I would be able to write decent C then I would have provided you with code but this will have to do.
Edit: A small demo in Python with GTK3
import gi
gi.require_version('Gtk', '3.0')
import gi.repository.Gtk as Gtk
class CompletingComboBoxText(Gtk.ComboBoxText):
def __init__(self, static_options, populator, **kwargs):
# Set up the ComboBox with the Entry
Gtk.ComboBoxText.__init__(self, has_entry=True, **kwargs)
# Store the populator reference in the object
self.populator = populator
# Create the completion
completion = Gtk.EntryCompletion(inline_completion=True)
# Specify that we want to use the first col of the model for completion
completion.set_text_column(0)
completion.set_minimum_key_length(2)
# Set the completion model to the combobox model such that we can also autocomplete these options
self.static_options_model = self.get_model()
completion.set_model(self.static_options_model)
# The child of the combobox is the entry if 'has_entry' was set to True
entry = self.get_child()
entry.set_completion(completion)
# Set the active option of the combobox to 0 (which is an empty field)
self.set_active(0)
# Fill the model with the static options (could also be used for a history or something)
for option in static_options:
self.append_text(option)
# Connect a listener to adjust the model when the user types something
entry.connect("changed", self.update_completion, True)
def update_completion(self, entry, editable):
# Get the current content of the entry
text = entry.get_text()
# Get the completion which needs to be updated
completion = entry.get_completion()
if text.startswith("_") and len(text) >= completion.get_minimum_key_length():
# Fetch the options from the populator for a given text
completion_options = self.populator(text)
# Create a temporary model for the completion and fill it
dynamic_model = Gtk.ListStore.new([str])
for completion_option in completion_options:
dynamic_model.append([completion_option])
completion.set_model(dynamic_model)
else:
# Restore the default static options
completion.set_model(self.static_options_model)
def demo():
# Create the window
window = Gtk.Window()
# Add some static options
fake_static_options = [
"comment",
"if",
"the_GUI",
"the_system",
"payload_json",
"x1",
"payload_json",
"payload_vectval"
]
# Add the the Combobox
ccb = CompletingComboBoxText(fake_static_options, dynamic_option_populator)
window.add(ccb)
# Show it
window.show_all()
Gtk.main()
def dynamic_option_populator(text):
# Some fake returns for the populator
fake_dynamic_options = [
"_5Hf0fFKvRVa71ZPM0",
"_8261sbF1f9ohzu2Iu",
"_0BV96V94PJIn9si1K",
"_0BV1sbF1f9ohzu2Iu",
"_0BV0fFKvRVa71ZPM0",
"_0Hf0fF4PJIn9si1Ks",
"_6KvRVa71JIn9si1Kw",
"_5HKvRVa71Va71ZPM0",
"_8261sbF1KvRVa71ZP",
"_0BKvRVa71JIn9si1K",
"_0BV1KvRVa71ZPu2Iu",
"_0BV0fKvRVa71ZZPM0",
"_0Hf0fF4PJIbF1f9oh",
"_61sbFV0fFKn9si1Kw",
"_5Hf0fFKvRVa71ozu2",
]
# Only return those that start with the text
return [fake_dynamic_option for fake_dynamic_option in fake_dynamic_options if fake_dynamic_option.startswith(text)]
if __name__ == '__main__':
demo()
Gtk.main()
Here is my suggestion:
Use a GtkListStore to contain a list of GTK-managed strings (essentially, copies of your identifier string) that match the current prefix string.
(As documented for gtk_list_store_set(), a G_TYPE_STRING item is copied. I consider the overhead of the extra copy acceptable here; it should not affect real-world performance much anyway, I think, and in return, GTK+ will manage the reference counting for us.)
The above is implemented in a GTK+ callback function, which gets an extra pointer as payload (set at the time the GUI is created or activated; I suggest you use some structure to keep references you need to generate the matches). The callback is connected to the combobox popup signal, so that it gets called whenever the list is expanded.
Note that as B8vrede noted in a comment, a GtkComboBoxText should not be modified via its model; that is why one should/must use a GtkComboBox instead.
Practical example
For simplicity, let's assume all the data you need to find or generate all known identifiers matched against is held in a structure, say
struct generator {
/* Whatever data you need to generate prefix matches */
};
and the combo box populator helper function is then something like
static void combo_box_populator(GtkComboBox *combobox, gpointer genptr)
{
struct generator *const generator = genptr;
GtkListStore *combo_list = GTK_LIST_STORE(gtk_combo_box_get_model(combobox));
GtkWidget *entry = gtk_bin_get_child(GTK_BIN(combobox));
const char *prefix = gtk_entry_get_text(GTK_ENTRY(entry));
const size_t prefix_len = (prefix) ? strlen(prefix) : 0;
GtkTreeIter iterator;
/* Clear the current store */
gtk_list_store_clear(combo_list);
/* Initialize the list iterator */
gtk_tree_model_get_iter_first(GTK_TREE_MODEL(combo_list), &iterator);
/* Find all you want to have in the combo box;
for each const char *match, do:
*/
gtk_list_store_append(combo_list, &iterator);
gtk_list_store_set(combo_list, &iterator, 0, match, -1);
/* Note that the string pointed to by match is copied;
match is not referred to after the _set() returns.
*/
}
When the UI is built or activated, you need to ensure the GtkComboBox has an entry (so the user can write text into it), and a GtkListStore model:
struct generator *generator;
GtkWidget *combobox;
GtkListStore *combo_list;
combo_list = gtk_list_store_new(1, G_TYPE_STRING);
combobox = gtk_combo_box_new_with_model_and_entry(GTK_TREE_MODEL(combo_list));
gtk_combo_box_set_id_column(GTK_COMBO_BOX(combobox), 0);
gtk_combo_box_set_entry_text_column(GTK_COMBO_BOX(combobox), 0);
gtk_combo_box_set_button_sensitivity(GTK_COMBO_BOX(combobox), GTK_SENSITIVITY_ON);
g_signal_connect(combobox, "popup", G_CALLBACK(combo_box_populator), generator);
On my system, the default pop-up accelerator is Alt+Down, but I assume you've already changed that to Tab.
I have a crude working example here (a .tar.xz tarball, CC0): it reads lines from standard input, and lists the ones matching the user prefix in reverse order in the combo box list (when popped-up). If the entry is empty, the combobox will contain all input lines. I didn't change the default accelerators, so instead of Tab, try Alt+Down.
I also have the same example, but using GtkComboBoxText instead, here (also CC0). This does not use a GtkListStore model, but uses gtk_combo_box_text_remove_all() and gtk_combo_box_text_append_text() functions to manipulate the list contents directly. (There is just a few different lines in the two examples.) Unfortunately, the documentation is not explicit whether this interface references or copies the strings. Although copying is the only option that makes sense, and this can be verified from the current Gtk+ sources, the lack of explicit documentation makes me hesitant.
Comparing the two examples I linked to above (both grab some 500 random words from /usr/share/dict/words if you compile and run it with make), I don't see any speed difference. Both use the same naïve way of picking prefix matches from a linked list, which means the two methods (GtkComboBox + model, or GtkComboBoxText) should be about equally fast.
On my own machine, both get annoyingly slow with more than 1000 or so matches in the popup; with just a hundred or less matches, it feels instantaneous. This, to me, indicates that the slow/naïve way of picking prefix matches from a linked list is not the culprit (because the entire list is traversed in both cases), but that the GTK+ combo boxes are just not designed for large lists. (The slowdown is definitely much, much worse than linear.)
I am using streambase, and have created a map to convert incoming integers (0-255) into character codes. Right now, I'm using manual if/else statements. For example:
if (message_code == '106') then
message_code = 'J'
else if (message_code == '110') then
message_code= 'N'
However, I'd like to just use this more generally. Searching Streambase Studio help didn't really provide anything as far as I could tell. I know this can be done in Java, but would probably require calling a java external function. I'm not so competent at this, so am a bit lost.
Is there a better way to do this in StreamBase?
Initial investigations confirm that the StreamBase Expression Language or built-in Functions don't have an obvious way to convert ints representing ASCII character values into a one-character string corresponding to the ASCII value. If there's some non-obvious trick I discover later, I'll come back and edit this answer.
I definitely wouldn't use a 255-clause if/then/else expression!
I would probably use a Java function and here is an example I've lightly tested:
package example;
public class ASCIIIntToString {
public static String ASCIIToString(Integer a) {
if (a == null || a < 0 || a > 255) {
return null;
} else {
return Character.toString((char) (int) a);
}
}
}
And the custom-function declaration to drop into your sbd.sbconf would look like this:
<custom-functions>
<custom-function alias="ASCIIToString"
args="auto"
class="example.ASCIIIntToString"
language="java"
name="ASCIIToString"
type="simple"/>
</custom-functions>
But if you would rather not drop into Java and stay in EventFlow then two methods come to mind:
Load a CSV file with int -> string mappings in them into a Query Table and dto a lookup with Query Read operator, perhaps using the Initial Contents tab to reference the CSV file since ASCII isn't going to change anytime soon.
Create a list constant called, say, ASCII, that has all the strings you want to convert to and index the list by the int. For example, in a Map operator do Add c ASCII[i], and add some bounds checking logic (perhaps in a user function).
Disclosure/Disclaimer: I am an employee of TIBCO Software, Inc. Opinions expressed here are my own and not TIBCO's.
I have a process which exposes a method to DBus with one of the arguments taking the following type signature a{sv}:
Dict of {String, Variant}
The libDBus documentation for dbus_message_append_args fails to provide adequate reference for this. Some information appears in the specification under container-types, specifically:
A DICT_ENTRY works exactly like a struct, but rather than parentheses
it uses curly braces, and it has more restrictions. The restrictions
are: it occurs only as an array element type; it has exactly two
single complete types inside the curly braces; the first single
complete type (the "key") must be a basic type rather than a container
type. Implementations must not accept dict entries outside of arrays,
must not accept dict entries with zero, one, or more than two fields,
and must not accept dict entries with non-basic-typed keys. A dict
entry is always a key-value pair.
On attempting to append a dict I receive the following error message:
type dict_entry isn't supported yet in dbus_message_append_args_valist
Although I'm actually using dbus_message_append_args(I guess the error message is somewhat off).
There are two other alternatives to dbus_message_append_args() using either:
dbus_message_iter_append_basic()
and
dbus_message_iter_append_fixed_array()
While I can create an empty Dict container with the following:
const char * container_d_sig = "{sv}";
DBusMessageIter iter, sub;
dbus_message_iter_init_append(msg, &iter);
dbus_message_iter_open_container(&iter, DBUS_TYPE_ARRAY, container_d_sig, &sub);
dbus_message_iter_close_container(&iter, &sub);
Neither of the append methods appear to support adding a struct. Not sure what to try here...
First, about D-Bus libraries: you talk about dbus-glib in several places but the functions you refer to are not part of dbus-glib but libdbus. If you are still trying to find the best way to use D-Bus, I suggest you forget both of these: libdbus is very low-level (it's documentation even starts with "If you use this low-level API directly, you're signing up for some pain") and dbus-glib is deprecated. The best D-Bus API currently is GDBus which is part of GLib GIO: it's a far better designed API than either of the other two, well tested and supported.
Now, as for the actual question, documentation for dbus_message_append_args() does say it quite clearly:
To append variable-length basic types, or any more complex value, you
have to use an iterator rather than this function.
In other words you should use dbus_message_iter_open_container() to prepare the iterator until it is pointing to somewhere where you can use dbus_message_iter_append_basic(). Note that in your example the dictionary is a container, the dictionary entry is a container and the variant is a container... In other words it gets pretty complex quite fast. If you really want to do it, look at e.g. Connman code for examples.
As I mentioned, the sane route is GDBus. There creating even much more complex signatures is pretty easy as you can use the GVariantBuilder API:
GVariantBuilder builder;
g_variant_builder_init (&builder, G_VARIANT_TYPE("a{sv}"));
g_variant_builder_add (&builder, "{sv}", "name1", my_variant);
/* Now use the builder results with g_dbus_connection_call()
or g_dbus_proxy_call() */
I know this question was asked awhile ago, but I had a very similar question recently, and after several hours of trial and error this is some code I came up with that works for me. Hopefully it helps someone else...
DBusMessage* testMessage()
{
DBusMessage* mssg = dbus_message_new_signal("/fi/w1/wpa_supplicant1/Interfaces/0", "fi.w1.wpa_supplicant1.Interface", "PropertiesChanged");
DBusMessageIter iter, aIter;
dbus_message_iter_init_append(mssg, &iter);
if (!dbus_message_iter_open_container(&iter, 'a', "{sv}", &aIter))
return nullptr;
DBusMessageIter eIter;
if (!dbus_message_iter_open_container(&aIter, 'e', NULL, &eIter)) {
dbus_message_iter_abandon_container_if_open(&iter, &aIter);
return nullptr;
}
const char* key = "test key";
dbus_message_iter_append_basic(&eIter, 's', static_cast<void*>(&key));
DBusMessageIter vIter;
if (!dbus_message_iter_open_container(&eIter, 'v', "i", &vIter)) {
dbus_message_iter_abandon_container_if_open(&aIter, &eIter);
dbus_message_iter_abandon_container_if_open(&iter, &aIter);
return nullptr;
}
dbus_int32_t val = 42;
dbus_message_iter_append_basic(&vIter, 'i', static_cast<void*>(&val));
dbus_message_iter_close_container(&eIter, &vIter);
dbus_message_iter_close_container(&aIter, &eIter);
dbus_message_iter_close_container(&iter, &aIter);
return mssg;
}
This is C++ but should be pretty easy to adapt for C. The returned message has a signature of a{sv}. The dbus docs are helpful-ish.