I have a treeview and want to get notified if the selection changes. What is the signature for the callback?
I found a code snippet like:
Gtk::TreeView *treeview = Gtk::manage(new Gtk::TreeView);
Glib::RefPtr< Gtk::TreeSelection > sel = treeview->get_selection();
sel->set_mode( Gtk::SELECTION_MULTIPLE );
sel->set_select_function(sigc::ptr_fun(&SelFun));
But I can't find anything about the SelFun!
How is the signature
How to find out which rows and columns are selected inside this function?
How to access data from the model with that object
Yes, I have actually no idea how the TreeView/Model/Path/Selection interacts. Every link to an example is highly welcome!
You seem to want multiple selection. I had the same problem too. Once you have enabled mutliple selection, getting the selected rows is a little more difficult. The method of acquiring them varies slightly.
I'll provide the most general method. First, you need to overload the signal_changed() signal after you have enabled multiple selection. Then, assign the TreeView's TreeSelection to a RefPtr for easy access.
Glib::RefPtr<Gtk::TreeSelection> TreeView_TreeSelection;
TreeView_TreeSelection = your_TreeView.get_selection();
Next, connect the TreeSelection to the signal_changed() signal.
TreeView_TreeSelection -> signal_changed().connect(sigc::mem_fun(your_TreeView,
&your_Class::on_selection_changed));
Now, make sure to make a void function header in "your_Class" named on_selction_changed() or whatever you want. Just make sure to change the name in the connection above to whatever your class' name is.
The final step is to make the function. Here is a simple example of getting a vector of all of the TreePaths of the rows selected, then converting those TreePaths into a vector of TreeModel::Row pointers.
void your_Class::on_selection_changed()
{
if((TreeView_TreeSelection -> count_selected_rows()) == 0)
{
return;
}
vector<Gtk::TreeModel::Path> selected_rows = TreeView_TreeSelection -> get_selected_rows();
vector<Gtk::TreeModel::Row*> selected_TreeRows;
vector<Gtk::TreeModel::Path>::iterator TreePath_iterator = selected_rows.begin();
Gtk::TreeRow *row;
while(TreePath_iterator != selected_rows.end()
{
selected_row_it = p_TreeModel -> get_iter(TreePath_iterator);
row = (*selected_row_it);
selected_TreeRows.push_back(row);
TreePath_iterator++;
}
}
Do you know how to iterate through a TreeModel using the STL-like contain API called children() of a TreeModel? It's most useful for iterating over all of the rows of a TreeModel or getting the size (AKA row count) of a TreeModel. Its use depends on whether you're using a ListStore, TreeStore or a custom TreeModel.
Related
I'm building a publish-subscribe class (called SystermInterface), which is responsible to receive updates from its instances, and publish them to subscribers.
Adding a subscriber callback function is trivial and has no issues, but removing it yields an error, because std::function<()> is not comparable in C++.
std::vector<std::function<void()> subs;
void subscribe(std::function<void()> f)
{
subs.push_back(f);
}
void unsubscribe(std::function<void()> f)
{
std::remove(subs.begin(), subs.end(), f); // Error
}
I've came down to five solutions to this error:
Registering the function using a weak_ptr, where the subscriber must keep the returned shared_ptr alive.
Solution example at this link.
Instead of registering at a vector, map the callback function by a custom key, unique per callback function.
Solution example at this link
Using vector of function pointers. Example
Make the callback function comparable by utilizing the address.
Use an interface class (parent class) to call a virtual function.
In my design, all intended classes inherits a parent class called
ServiceCore, So instead of registering a callback function, just
register ServiceCore reference in the vector.
Given that the SystemInterface class has a field attribute per instance (ID) (Which is managed by ServiceCore, and supplied to SystemInterface by constructing a ServiceCore child instance).
To my perspective, the first solution is neat and would work, but it requires handling at subscribers, which is something I don't really prefer.
The second solution would make my implementation more complex, where my implementation looks as:
using namespace std;
enum INFO_SUB_IMPORTANCE : uint8_t
{
INFO_SUB_PRIMARY, // Only gets the important updates.
INFO_SUB_COMPLEMENTARY, // Gets more.
INFO_SUB_ALL // Gets all updates
};
using CBF = function<void(string,string)>;
using INFO_SUBTREE = map<INFO_SUB_IMPORTANCE, vector<CBF>>;
using REQINF_SUBS = map<string, INFO_SUBTREE>; // It's keyed by an iterator, explaining it goes out of the question scope.
using INFSRC_SUBS = map<string, INFO_SUBTREE>;
using WILD_SUBS = INFO_SUBTREE;
REQINF_SUBS infoSubrs;
INFSRC_SUBS sourceSubrs;
WILD_SUBS wildSubrs;
void subscribeInfo(string info, INFO_SUB_IMPORTANCE imp, CBF f) {
infoSubrs[info][imp].push_back(f);
}
void subscribeSource(string source, INFO_SUB_IMPORTANCE imp, CBF f) {
sourceSubrs[source][imp].push_back(f);
}
void subscribeWild(INFO_SUB_IMPORTANCE imp, CBF f) {
wildSubrs[imp].push_back(f);
}
The second solution would require INFO_SUBTREE to be an extended map, but can be keyed by an ID:
using KEY_T = uint32_t; // or string...
using INFO_SUBTREE = map<INFO_SUB_IMPORTANCE, map<KEY_T,CBF>>;
For the third solution, I'm not aware of the limitations given by using function pointers, and the consequences of the fourth solution.
The Fifth solution would eliminate the purpose of dealing with CBFs, but it'll be more complex at subscriber-side, where a subscriber is required to override the virtual function and so receives all updates at one place, in which further requires filteration of the message id and so direct the payload to the intended routines using multiple if/else blocks, which will increase by increasing subscriptions.
What I'm looking for is an advice for the best available option.
Regarding your proposed solutions:
That would work. It can be made easy for the caller: have subscribe() create the shared_ptr and corresponding weak_ptr objects, and let it return the shared_ptr.
Then the caller must not lose the key. In a way this is similar to the above.
This of course is less generic, and then you can no longer have (the equivalent of) captures.
You can't: there is no way to get the address of the function stored inside a std::function. You can do &f inside subscribe() but that will only give you the address of the local variable f, which will go out of scope as soon as you return.
That works, and is in a way similar to 1 and 2, although now the "key" is provided by the caller.
Options 1, 2 and 5 are similar in that there is some other data stored in subs that refers to the actual std::function: either a std::shared_ptr, a key or a pointer to a base class. I'll present option 6 here, which is kind of similar in spirit but avoids storing any extra data:
Store a std::function<void()> directly, and return the index in the vector where it was stored. When removing an item, don't std::remove() it, but just set it to std::nullptr. Next time subscribe() is called, it checks if there is an empty element in the vector and reuses it:
std::vector<std::function<void()> subs;
std::size_t subscribe(std::function<void()> f) {
if (auto it = std::find(subs.begin(), subs.end(), std::nullptr); it != subs.end()) {
*it = f;
return std::distance(subs.begin(), it);
} else {
subs.push_back(f);
return subs.size() - 1;
}
}
void unsubscribe(std::size_t index) {
subs[index] = std::nullptr;
}
The code that actually calls the functions stored in subs must now of course first check against std::nullptrs. The above works because std::nullptr is treated as the "empty" function, and there is an operator==() overload that can check a std::function against std::nullptr, thus making std::find() work.
One drawback of option 6 as shown above is that a std::size_t is a rather generic type. To make it safer, you might wrap it in a class SubscriptionHandle or something like that.
As for the best solution: option 1 is quite heavy-weight. Options 2 and 5 are very reasonable, but 6 is, I think, the most efficient.
I currently have two macros that are part of a (very limited-audience) plugin I'm developing, that both look basically like:
(function(){
exports.name = "name";
exports.params = [
{name: "value"}
];
function get(tiddler) {
// return some contents of some tiddler fields according to some rule
}
function parse(data) {
// convert string to some kind of useful object
}
function logic(x, y) {
// determine whether the two objects correspond in some way
};
function format(data, title) {
// produce WikiText for a link with some additional decoration
};
exports.run = function(value) {
value = parse(value);
var result = [];
this.wiki.each(function(tiddler, title) {
var data = get(tiddler);
if (data !== undefined && logic(value, parse(data))) {
result.push(format(data, title));
}
});
return result.join(" | ");
};
})();
So they're already fairly neatly factored when considered individually; the problem is that only the core logic is really different between the two macros. How can I share the functions get, logic and format between the macros? I tried just putting them in a separate tiddler, but that doesn't work; when the macros run, TW raises an error claiming that the functions are "not defined". Wrapping each function as its own javascript macro in a separate tiddler, e.g.
(function(){
exports.name = "get";
exports.params = [
{name: "tiddler"}
];
exports.run = function(tiddler) {
// return some contents of some tiddler fields according to some rule
}
})();
also didn't help.
I'd also like to set this up to be more modular/flexible, by turning the main get/parse/logic/format process into a custom filter, then letting a normal filter expression take care of the iteration and using e.g. the widget or <> macro to display the items. How exactly do I set this up? The documentation tells me
If the provided filter operators are not enough, a developer can add
new filters by adding a module with the filteroperator type
but I can't find any documentation of the API for this, nor any examples.
How can I share the functions get, logic and format between the macros?
You can use the Common/JS standard require('<tiddler title>') syntax to access the exports of another tiddler. The target tiddler should be set up as a JS module (ie, the type field set to application/javascript and the module-type field set to library). You can see an example here:
https://github.com/Jermolene/TiddlyWiki5/blob/master/core/modules/widgets/count.js#L15
I'd also like to set this up to be more modular/flexible, by turning the main get/parse/logic/format process into a custom filter, then letting a normal filter expression take care of the iteration and using e.g. the widget or <> macro to display the items. How exactly do I set this up?
The API for writing filter operators isn't currently documented, but there are many examples to look at:
https://github.com/Jermolene/TiddlyWiki5/tree/master/core/modules/filters
I am working on a web api project (back end) and I am searching for some more optimized way to get multiple parameter from front end. There are numerous ways like
i) name each parameter in action parameter stack
ii) extract from request body like Request.Content.ReadAsStringAsync().Result;
iii) define complex types (model) and use that type to receive values. like MyAction(UserLog log)
I have to create hundreds of functions which may take variable number of parameters. I don't want to use first option above, it is hectic for large data.
The second is confusing as no one can predict what to post.
The third one forces me to create hundreds of input models. So is there any better way to do so?
You could try using a form data collection
Its basically a Key Value Pair which allows for an element of genericness.
Edit - another link
Another option would be to apply dynamic object parameters on your Post Verbs.
E.g.
public string Post(dynamic value)
{
string s = "";
foreach (dynamic item in value)
{
s = s + item.content + " ";
}
return s;
}
Per the docs, "The call operator always returns the current selection, regardless of the return value of the specified function." I'd like to know if there is a variant of call or reasonable workaround for getting call-behavior that returns values other than the selection.
Motivation:
I've got a chart and a datebrush, each encapsulated in a function
function trends_datebrush() {
// Setup
function chart(_selection) {
_selection.each(function(_data) {
// Do things
...});
}
return chart;
};
(The chart follows a similar format but isn't called datebrush).
These are instantiated with:
d3.select("someDiv")
.datum("data")
.call(trends_datebrush());
// And then we call the chart
I'd like to return a subselection from brush to be used as the data variable in the chart call. As is I need to make them both aware of some higher order global state, which gets messy especially since I want other control functions to drill down on the data. If I could override call, then I could do something like
d3.select("someDiv")
.datum("data")
.call(trends_datebrush())
.call(trends_chart());
And then if I were to implement some new filter I could throw it into the chain with another call statement.
tl;DR: Looking for ways to get chain chart calls s.t. they can pass transformed data to each other. I want monadic D3 charts! Except I don't really know monads so I might be misusing the word.
I have the following UnitTest:
[TestMethod]
public void NewGamesHaveDifferentSecretCodesTothePreviousGame()
{
var theGame = new BullsAndCows();
List<int> firstCode = new List<int>(theGame.SecretCode);
theGame.NewGame();
List<int> secondCode = new List<int>(theGame.SecretCode);
theGame.NewGame();
List<int> thirdCode = new List<int>(theGame.SecretCode);
CollectionAssert.AreNotEqual(firstCode, secondCode);
CollectionAssert.AreNotEqual(secondCode, thirdCode);
}
When I run it in Debug mode, my code passes the test, but when I run the test as normal (run mode) it does not pass. The exception thrown is:
CollectionAssert.AreNotEqual failed. (Both collection contain same elements).
Here is my code:
// constructor
public BullsAndCows()
{
Gueses = new List<Guess>();
SecretCode = generateRequiredSecretCode();
previousCodes = new Dictionary<int, List<int>>();
}
public void NewGame()
{
var theCode = generateRequiredSecretCode();
if (previousCodes.Count != 0)
{
if(!isPreviouslySeen(theCode))
{
SecretCode = theCode;
previousCodes.Add(previousCodes.Last().Key + 1, SecretCode);
}
}
else
{
SecretCode = theCode;
previousCodes.Add(0, theCode);
}
}
previousCodes is a property on the class, and its Data type is Dictionary key integer, value List of integers. SecretCode is also a property on the class, and its Data type is a List of integers
If I were to make a guess, I would say the reason is the NewGame() method is called again, whilst the first call hasn't really finished what it needs to do. As you can see, there are other methods being called from within the NewGame() method (e.g. generateRequiredSecretCode()).
When running in Debug mode, the slow pace of my pressing F10 gives sufficient time for processes to end.
But I am not really sure how to fix that, assuming I am right in my identification of the cause.
What happens to SecretCode when generateRequiredSecretCode generates a duplicate? It appears to be unhandled.
One possibility is that you are getting a duplicate, so SecretCode remain the same as its previous value. How does the generator work?
Also, you didn't show how the BullsAndCows constructor is initializing SecretCode? Is it calling NewGame?
I doubt the speed of keypresses has anything to do with it, since your test method calls the functions in turn without waiting for input. And unless generateReq... is spawning a thread, it will complete whatever it is doing before it returns.
--after update--
I see 2 bugs.
1) The very first SecretCode generated in the constructor is not added to the list of previousCodes. So the duplicate checking won't catch if the 2nd game has the same code.
2) after previousCodes is populated, you don't handle the case where you generate a duplicate. a duplicate is previouslySeen, so you don't add it to the previousCodes list, but you don't update SecretCode either, so it keeps the old value.
I'm not exactly sure why this is only showing up in release mode - but it could be a difference in the way debug mode handles the random number generator. See How to randomize in WPF. Release mode is faster, so it uses the same timestamp as seed, so it does in fact generate exactly the same sequence of digits.
If that's the case, you can fix it by making random a class property instead of creating a new one for each call to generator.