This repository contains the EQUATE dataset, and the Q-REAS symbolic reasoning baseline[1].
EQUATE
EQUATE (Evaluating Quantitative Understanding Aptitude in Textual Entailment) is a new framework for evaluating quantitative reasoning ability in textual entailment.
EQUATE consists of five NLI test sets featuring quantities. You can download EQUATE here. Three of these tests for quantitative reasoning feature language from real-world sources
such as news articles and social media (RTE, NewsNLI Reddit), and two are controlled synthetic tests, evaluating model ability
to reason with quantifiers and perform simple arithmetic (AWP, Stress Test).
Models reporting performance on any NLI dataset can additionally evaluate on the EQUATE benchmark,
to demonstrate competence at quantitative reasoning.
Q-Reas
We also provide a baseline quantitative reasoner Q-Reas. Q-Reas manipulates quantity representations symbolically to make entailment decisions.
We hope this provides a framework for the development of hybrid neuro-symbolic architectures to combine the strengths of symbolic reasoners and
neural models.
Q-Reas has five modules:
Quantity Segmenter: Extracts quantity mentions
Quantity Parser: Parses mentions into semantic representations called NUMSETS
@article{ravichander2019equate,
title={EQUATE: A Benchmark Evaluation Framework for Quantitative Reasoning in Natural Language Inference},
author={Ravichander, Abhilasha and Naik, Aakanksha and Rose, Carolyn and Hovy, Eduard},
journal={arXiv preprint arXiv:1901.03735},
year={2019}
}
Kafka, Zookeeper, and Confluent’s command-line tools in a docker image.
Overview
This is a docker image that provides the confluent platform tools. This can be utilized to run the Kafka, Zookeeper, or Confluent tools locally without having to install them. It can also be deployed alongside Kafka & Zookeeper so one can utilize the tools in a live setting. It’s also quite useful for running these tools on Windows machines.
Getting Started
Ensure you have Docker installed. Pull down the image:
docker pull devshawn/confluent-tools
Singleton mode
If you just need to run a command locally and don’t need to keep the container running, you can execute commands without a background daemon container.
docker run --net=host -it --entrypoint run devshawn/confluent-tools {cmd}
For example, listing Kafka topics with local zookeeper running:
docker run --net=host -it --entrypoint run devshawn/confluent-tools kafka-topics --list --zookeeper localhost:2181
Daemon mode
The container can be run in daemon mode and act as a running machine with the tools installed. Start the container:
docker run -d --name confluent-tools --net=host devshawn/confluent-tools
The container will now be running. We set the following properties:
-d: run container in daemon mode
–name: set the container name
–net=host: run container with access to localhost (i.e. kafka running locally)
Execute Single Commands
You can run single commands such as:
docker exec -it confluent-tools {cmd}
For example, listing Kafka topics with local zookeeper running:
If you’re going to be running a lot of commands, it’s easier to run them from inside of the container. First, open a shell inside of the container:
docker exec -it confluent-tools /bin/bash
You’ll now see something such as:
bash-4.4#
From here, run commands as if they were on your local machine. For example, listing Kafka topics with a local zookeeper running:
kafka-topics --list --zookeeper localhost:2181
Ackowledgements
This project was made to make utilizing the confluent tools easier on local machines. All credit to the Confluent team and many open source contributors. ❤️
Automated Multi Speaker diarization API for meetings, calls, interviews, press-conference etc.
DeepAffects Speaker diarization API tries to figure out “Who Speaks When”. It essentially splits audio clip into segments corresponding to a unique speaker.
POST Request
POST https://proxy.api.deepaffects.com/audio/generic/api/v2/async/diarize
varDeepAffects=require("deep-affects");vardefaultClient=DeepAffects.ApiClient.instance;// Configure API key authorization: UserSecurityvarUserSecurity=defaultClient.authentications["UserSecurity"];UserSecurity.apiKey="<API_KEY>";varapiInstance=newDeepAffects.DiarizeApiV2();varbody=DeepAffects.DiarizeAudio.fromFile("/path/to/file");// DiarizeAudio | Audio object that needs to be diarized.varcallback=function(error,data,response){if(error){console.error(error);}else{console.log("API called successfully. Returned data: "+data);}};webhook="https://your/webhook/";// async requestapiInstance.asyncDiarizeAudio(body,webhook,callback);
Python
importrequestsimportbase64url="https://proxy.api.deepaffects.com/audio/generic/api/v2/async/diarize"querystring= {"apikey":"<API_KEY>", "webhook":"<WEBHOOK_URL>", "request_id":"<OPTIONAL_REQUEST_ID>"}
payload= {
"encoding": "Wave",
"languageCode": "en-US",
"speakers": -1,
"doVad": true
}
# The api accepts data either as a url or as base64 encoded content# passing payload as url:payload["url"] ="https://publicly-facing-url.wav"# alternatively, passing payload as content:withopen(audio_file_name, 'rb') asfin:
audio_content=fin.read()
payload["content"] =base64.b64encode(audio_content).decode('utf-8')
headers= {
'Content-Type': "application/json",
}
response=requests.post(url, data=payload, headers=headers, params=querystring)
print(response.text)
Number of speakers in the file (-1 for unknown speakers)
[default to -1]
audioType
String
Type of the audio based on number of speakers
[default to callcenter]
speakerIds
List[String]
Optional set of speakers to be identified from the call
[default to []]
doVad
Bool
Apply voice activity detection
[default to False]
audioType: can have two values 1) callcenter 2) meeting. We recommend using callcenter when there are two speakers expected to be identified and meeting when multiple speakers are expected.
doVad: Default=False. This parameters is required if you want silence & noise segments removed from the diarization output.
Query Parameters
Parameter
Type
Description
Notes
api_key
String
The apikey
Required for authentication inside all requests
webhook
String
The webhook url at which the responses will be sent
Required for async requests
request_id
Number
An optional unique id to link async response with the original request
Optional
Output Parameters (Async)
Parameter
Type
Description
Notes
request_id
String
The request id
This defaults to the originally sent id or is generated by the api
api
String
The api method which was called
Output Parameters (Webhook)
Parameter
Type
Description
Notes
request_id
String
The request id
This defaults to the originally sent id or is generated by the api
response
Object
The actual output of the diarization
The Diarized object is defined below
Diarized Object
Parameter
Type
Description
Notes
num_speakers
Number
The number of speakers detected
The number of speaker will be detected only when the request set speakers to -1
segments
List
List of diarized segments
The Diarized Segment is defined below
Diarized Segment
Parameter
Type
Description
Notes
speaker_id
Number
The speaker id for the corresponding audio segment
start
Number
Start time of the audio segment in seconds
end
Number
End time of the audio segment in seconds
About
DeepAffects is a speech analysis platform for Developers. We offer a number of speech analysis apis like, Speech Enhancement, Multi-Speaker Diarization, Emotion Recognition, Voice-prints, Conversation Metrics etc. For more information, checkout our developer portal
Projects from the 42 Cursus to date. Studies commenced 21 February 2022.
Note regarding the following table:
CCR stands for Common Core Rank, it represents what stage you are at in your studies. To validate your studies you must complete Libft(CCR 0). Afterwards, there are 6 CCRs and 5 exams total (exam02-exam06). Each exam will advance you to the subsequent rank.
This project will make you sort data on a stack, with a limited set of instructions, using the lowest possible number of actions. To succeed you’ll have to manipulate various types of algorithms and choose the most appropriate solution (out of many) for an optimised data sorting.
Complete
FdF
2
This project is about representing a landscape as a 3D object in which all surfaces are outlined in lines.
Complete
Philosophers
3
In this project, you will learn the basics of threading a process. You will see how to create threads and you will discover mutexes.
This project is inspired by the world-famous eponymous 90’s game, which was the first FPS ever. It will enable you to explore ray-casting. Your goal will be to make a dynamic view inside a maze, in which you’ll have to find your way.
Complete
NetPractice
4
NetPractice is a general practical exercise to let you discover networking.
This project aims to broaden your knowledge of system administration by using Docker. You will virtualize several Docker images, creating them in your new personal virtual machine.
This Pre–pre-pre-alpha GitHub template repository includes PLANNEDPython library, GNNgraph.py with some basic Sphinx docs … this is mostly about LEARNING and enjoying learning by exploring a graph, which might be like a syllabus, except that it’s more convoluted, branching and tangled … it is about LEARNING in an autodiadactic hands on manner OR doing things the hard way before making them scale OR proceeding from first principles or from scratch OR taking it step-by-step but paying most attention to the assumptions, rather than narrowing the choices down on a multiple choice test.
The GNNgraph project is about learning how to use data APIs and then wrangling data to be able to parse simple json, csv or minimally formatted txt files into a visual, navigable knowledge-graph.
It’s all about the connections and the emergent patterns in data.
Obviously, using reStructuredText to parse this documentation is a deliberate choice which is not just about relying upon the very simple, highly stable docutils codebase.
We envision an annotatable, forkable knowledge-graph which would provide digraph visualization of related modeling approach for comparisons and analyis, as well as ready navigation directly to different executable Python snackable tutorials for learning about how different families of neural network model works … along with an annotated bibliography of related papers with code and data in the area.
This repository itself began its life as a fork the ReadTheDocsTutorial. The larger process of how Sphinx works and how forkable tutorial templates like this are built to be integrated with various version control system providers is itself very interesting to anyone exploring how knowledge can be version controlled then forked, shared, work with the universe of Git tools and part of social issues-driven discussion or even pair programming on a platform like GitHub or GitLab… and will be historically, long after after this project is operational.
Following objectives are tested through this certification
## DATA INGESTION- Import data from a table in a relational database into HDFS
- Import the results of a query from a relational database into HDFS
- Import a table from a relational database into a new or existing Hive table
- Insert or update data from HDFS into a table in a relational database
- Given a Flume configuration file, start a Flume agent
- Given a configured sink and source, configure a Flume memory channel with a specified capacity
## DATA TRANSFORMATION- Write and execute a Pig script
- Load data into a Pig relation without a schema
- Load data into a Pig relation with a schema
- Load data from a Hive table into a Pig relation
- Use Pig to transform data into a specified format
- Transform data to match a given Hive schema
- Group the data of one or more Pig relations
- Use Pig to remove records with null values from a relation
- Store the data from a Pig relation into a folder in HDFS
- Store the data from a Pig relation into a Hive table
- Sort the output of a Pig relation
- Remove the duplicate tuples of a Pig relation
- Specify the number of reduce tasks for a Pig MapReduce job
- Join two datasets using Pig
- Perform a replicated join using Pig
- Run a Pig job using Tez
- Within a Pig script, register a JAR file of User Defined Functions
- Within a Pig script, define an alias for a User Defined Function
- Within a Pig script, invoke a User Defined Function
## DATA ANALYSIS- Write and execute a Hive query
- Define a Hive-managed table
- Define a Hive external table
- Define a partitioned Hive table
- Define a bucketed Hive table
- Define a Hive table from a select query
- Define a Hive table that uses the ORCFile format
- Create a new ORCFile table from the data in an existing non-ORCFile Hive table
- Specify the storage format of a Hive table
- Specify the delimiter of a Hive table
- Load data into a Hive table from a local directory
- Load data into a Hive table from an HDFS directory
- Load data into a Hive table as the result of a query
- Load a compressed data file into a Hive table
- Update a row in a Hive table
- Delete a row from a Hive table
- Insert a new row into a Hive table
- Join two Hive tables
- Run a Hive query using Tez
- Run a Hive query using vectorization
- Output the execution plan for a Hive query
- Use a subquery within a Hive query
- Output data from a Hive query that is totally ordered across multiple reducers
- Set a Hadoop or Hive configuration property from within a Hive query
Google recommends Glide for simplifying the complexity of
managing Android.Graphics.Bitmap within your apps (docs
here).
glidex.forms is small library we can use to improve Xamarin.Forms
image performance on Android by taking a dependency on Glide. See my
post on the topic here.
If you have a “classic” Xamarin.Android app that is not Xamarin.Forms, it could be useful to use the Xamarin.Android.Glide NuGet package. If you want to improve the Xamarin binding for Glide, contribute to it on Github!
How do I use glidex.forms?
To set this library up in your existing project, merely:
Add the glidex.forms NuGet package
Add this one liner after your app’s Forms.Init call:
Xamarin.Forms.Forms.Init(this,bundle);//This forces the custom renderers to be usedAndroid.Glide.Forms.Init(this);LoadApplication(newApp());
How do I know my app is using Glide?
On first use, you may want to enable debug logging:
Android.Glide.Forms.Init(this,debug:true);
glidex.forms will print out log messages in your device log as to what is happening under the hood.
If you want to customize how Glide is used in your app, currently your option is to implement your own IImageViewHandler. See the GlideExtensions class for details.
Comparing Performance
It turns out it is quite difficult to measure performance improvements specifically for images in Xamarin.Forms. Due to the asynchronous nature of how images load, I’ve yet to figure out good points at which to clock times via a Stopwatch.
So instead, I found it much easier to measure memory usage. I wrote a quick class that runs a timer and calls the Android APIs to grab memory usage.
Here is a table of peak memory used via the different sample pages I’ve written:
NOTE: this was a past comparison with Xamarin.Forms 2.5.x
Page
Loaded by
Peak Memory Usage
GridPage
Xamarin.Forms
268,387,112
GridPage
glidex.forms
16,484,584
ViewCellPage
Xamarin.Forms
94,412,136
ViewCellPage
glidex.forms
12,698,112
ImageCellPage
Xamarin.Forms
24,413,600
ImageCellPage
glidex.forms
9,977,272
HugeImagePage
Xamarin.Forms
267,309,792
HugeImagePage
glidex.forms
9,943,184
NOTE: I believe these numbers are in bytes. I restarted the app (release mode) before recording the numbers for each page. Pages with ListViews I scrolled up and down a few times.
Stock XF performance of images is poor due to the amount of
Android.Graphics.Bitmap instances created on each page. Disabling
the Glide library in the sample app causes “out of memory” errors to
happen as images load. You will see empty white squares where this
occurs and get console output.
To try stock Xamarin.Forms behavior yourself, you can remove the
references to glidex and glidex.forms in the glide.forms.sample
project and comment out the Android.Glide.Forms.Init() line.
Features
In my samples, I tested the following types of images:
ImageSource.FromFile with a temp file
ImageSource.FromFile with AndroidResource
ImageSource.FromResource with EmbeddedResource
ImageSource.FromUri with web URLs
ImageSource.FromStream with AndroidAsset
For example, the GridPage loads 400 images into a grid with a random combination of all of the above:
Whether you want to test the client installation or simply check more examples on how the client works, take a look at tests and examples directory.
Installing
In order to install the JavaScript client, you only need to use npm.
npm install slicerjs
Usage
The following code snippet is an example of how to add and query data
using the SlicingDice javascript client. We entry data informing user1@slicingdice.com has age 22 and then query the database for
the number of users with age between 20 and 40 years old.
If this is the first register ever entered into the system,
the answer should be 1.
varSlicingDice=require('slicerjs');// only required for Node.js// Configure the clientconstclient=newSlicingDice({masterKey: 'MASTER_API_KEY',writeKey: 'WRITE_API_KEY',readKey: 'READ_API_KEY'});// Inserting dataconstinsertData={"user1@slicingdice.com": {"age": 22},"auto-create": ["dimension","column"]};client.insert(insertData);// Querying dataconstqueryData={"query-name": "users-between-20-and-40","query": [{"age": {"range": [20,40]}}]};client.countEntity(queryData).then((resp)=>{console.log(resp);},(err)=>{console.err(err);});
Reference
SlicingDice encapsulates logic for sending requests to the API. Its methods are thin layers around the API endpoints, so their parameters and return values are JSON-like Object objects with the same syntax as the API endpoints
Constructor
SlicingDice(apiKeys)
apiKeys (Object) – API key to authenticate requests with the SlicingDice API.
getDatabase()
Get information about current database. This method corresponds to a GET request at /database.
Verify which entities exist in a tabdimensionle (uses default dimension if not provided) given a list of entity IDs. This method corresponds to a POST request at /query/exists/entity.
Retrieve inserted values as well as their relevance for entities matching the given query. This method corresponds to a POST request at /data_extraction/score.
Retrieve inserted values using a SQL syntax. This method corresponds to a POST request at /query/sql.
Query statement
letSlicingDice=require('slicerjs');constclient=newSlicingDice({masterKey: 'MASTER_KEY',readKey: 'READ_KEY'});query="SELECT COUNT(*) FROM default WHERE age BETWEEN 0 AND 49";client.sql(query).then((resp)=>{console.log(resp);},(err)=>{console.error(err);});
Insert statement
letSlicingDice=require('slicerjs');constclient=newSlicingDice({masterKey: 'MASTER_KEY',readKey: 'READ_KEY'});query="INSERT INTO default([entity-id], name, age) VALUES(1, 'john', 10)";client.sql(query).then((resp)=>{console.log(resp);},(err)=>{console.error(err);});
The reflection system was born within EnTT
and is developed and enriched there. This project is designed for those who
are interested only in a header-only, full-featured, non-intrusive and macro
free reflection system which certainly deserves to be treated also separately
due to its quality and its rather peculiar features.
If you use meta and you want to say thanks or support the project, please
consider becoming a
sponsor.
You can help me make the difference.
Many thanks to those who supported me
and still support me today.
Reflection (or rather, its lack) is a trending topic in the C++ world. I looked
for a third-party library that met my needs on the subject, but I always came
across some details that I didn’t like: macros, being intrusive, too many
allocations.
In one word: unsatisfactory.
I finally decided to write a built-in, non-intrusive and macro-free runtime
reflection system for my own.
Maybe I didn’t do better than others or maybe yes. Time will tell me.
Build Instructions
Requirements
To be able to use meta, users must provide a full-featured compiler that
supports at least C++17.
The requirements below are mandatory to compile the tests and to extract the
documentation:
CMake version 3.2 or later.
Doxygen version 1.8 or later.
If you are looking for a C++14 version of meta, feel free to
contact me.
Library
meta is a header-only library. This means that including the factory.hpp and
meta.hpp headers is enough to include the library as a whole and use it.
It’s a matter of adding the following lines to the top of a file:
Then pass the proper -I argument to the compiler to add the src directory to
the include paths.
Documentation
The documentation is based on doxygen.
To build it:
$ cd build
$ cmake .. -DBUILD_DOCS=ON
$ make
The API reference will be created in HTML format within the directory
build/docs/html. To navigate it with your favorite browser:
$ cd build
$ your_favorite_browser docs/html/index.html
It’s also available online for the latest
version.
Tests
To compile and run the tests, meta requires googletest. cmake will download and compile the library before compiling anything else.
In order to build without tests set CMake option BUILD_TESTING=OFF.
To build the most basic set of tests:
$ cd build
$ cmake ..
$ make
$ make test
Crash course
Names and identifiers
The meta system doesn’t force the user to use a specific tool when it comes to
working with names and identifiers. It does this by offering an API that works
with opaque identifiers that for example may or may not be generated by means of
a hashed string.
This means that users can assign any type of identifier to the meta objects, as
long as they are numeric. It doesn’t matter if they are generated at runtime, at
compile-time or with custom functions.
However, the examples in the following sections are all based on
std::hash<std::string_view> as provided by the standard library. Therefore,
where an identifier is required, it’s likely that an instance of this class is
used as follows:
std::hash<std::string_view> hash{};
auto factory = meta::reflect<my_type>(hash("reflected_type"));
For what it’s worth, this is likely completely equivalent to:
auto factory = meta::reflect<my_type>(42);
Obviously, human-readable identifiers are more convenient to use and highly
recommended.
Reflection in a nutshell
Reflection always starts from real types (users cannot reflect imaginary types
and it would not make much sense, we wouldn’t be talking about reflection
anymore).
To reflect a type, the library provides the reflect function:
It accepts the type to reflect as a template parameter and an optional
identifier as an argument. Identifiers are important because users can retrieve
meta types at runtime by searching for them by name. However, there are cases
in which users can be interested in adding features to a reflected type so that
the reflection system can use it correctly under the hood, but they don’t want
to allow searching the type by name.
In both cases, the returned value is a factory object to use to continue
building the meta type.
A factory is such that all its member functions returns the factory itself.
It can be used to extend the reflected type and add the following:
Constructors. Actual constructors can be assigned to a reflected type by
specifying their list of arguments. Free functions (namely, factories) can be
used as well, as long as the return type is the expected one. From a client’s
point of view, nothing changes if a constructor is a free function or an
actual constructor.
Use the ctor member function for this purpose:
Destructors. Free functions can be set as destructors of reflected types.
The purpose is to give users the ability to free up resources that require
special treatment before an object is actually destroyed.
Use the dtor member function for this purpose:
A function should neither delete nor explicitly invoke the destructor of a
given instance.
Data members. Both real data members of the underlying type and static and
global variables, as well as constants of any kind, can be attached to a meta
type. From a client’s point of view, all the variables associated with the
reflected type will appear as if they were part of the type itself.
Use the data member function for this purpose:
This function requires as an argument the identifier to give to the meta data
once created. Users can then access meta data at runtime by searching for them
by name.
Data members can be set also by means of a couple of functions, namely a
setter and a getter. Setters and getters can be either free functions, member
functions or mixed ones, as long as they respect the required signatures.
Refer to the inline documentation for all the details.
Member functions. Both real member functions of the underlying type and free
functions can be attached to a meta type. From a client’s point of view, all
the functions associated with the reflected type will appear as if they were
part of the type itself.
Use the func member function for this purpose:
This function requires as an argument the identifier to give to the meta
function once created. Users can then access meta functions at runtime by
searching for them by name.
Base classes. A base class is such that the underlying type is actually
derived from it. In this case, the reflection system tracks the relationship
and allows for implicit casts at runtime when required.
Use the base member function for this purpose:
From now on, wherever a base_type is required, an instance of derived_type
will also be accepted.
Conversion functions. Actual types can be converted, this is a fact. Just
think of the relationship between a double and an int to see it. Similar
to bases, conversion functions allow users to define conversions that will be
implicitly performed by the reflection system when required.
Use the conv member function for this purpose:
meta::reflect<double>().conv<int>();
That’s all, everything users need to create meta types and enjoy the reflection
system. At first glance it may not seem that much, but users usually learn to
appreciate it over time.
Also, do not forget what these few lines hide under the hood: a built-in,
non-intrusive and macro-free system for reflection in C++. Features that are
definitely worth the price, at least for me.
Any as in any type
The reflection system comes with its own meta any type. It may seem redundant
since C++17 introduced std::any, but it is not.
In fact, the type returned by an std::any is a const reference to an
std::type_info, an implementation defined class that’s not something everyone
wants to see in a software. Furthermore, the class std::type_info suffers from
some design flaws and there is even no way to convert an std::type_info into
a meta type, thus linking the two worlds.
A meta any object provides an API similar to that of its most famous counterpart
and serves the same purpose of being an opaque container for any type of
value.
It minimizes the allocations required, which are almost absent thanks to SBO
techniques. In fact, unless users deal with fat types and create instances of
them though the reflection system, allocations are at zero.
A meta any object can be created by any other object or as an empty container
to initialize later:
// a meta any object that contains an int
meta::any any{0};
// an empty meta any object
meta::any empty{};
It takes the burden of destroying the contained instance when required.
Moreover, it can be used as an opaque container for unmanaged objects if needed:
int value;
meta::any any{std::ref(value)};
In other words, whenever any intercepts a reference_wrapper, it acts as a
reference to the original instance rather than making a copy of it. The
contained object is never destroyed and users must ensure that its lifetime
exceeds that of the container.
A meta any object has a type member function that returns the meta type of the
contained value, if any. The member functions try_cast, cast and convert
are used to know if the underlying object has a given type as a base or if it
can be converted implicitly to it.
Enjoy the runtime
Once the web of reflected types has been constructed, it’s a matter of using it
at runtime where required.
To search for a reflected type there are two options: by type or by name. In
both cases, the search can be done by means of the resolve function:
// search for a reflected type by type
meta::type by_type = meta::resolve<my_type>();
// search for a reflected type by name
meta::type by_name = meta::resolve(hash("reflected_type"));
There exits also a third overload of the resolve function to use to iterate
all the reflected types at once:
resolve([](meta::type type) {
// ...
});
In all cases, the returned value is an instance of type. This type of objects
offer an API to know the runtime identifier of the type, to iterate all the
meta objects associated with them and even to build or destroy instances of the
underlying type.
Refer to the inline documentation for all the details.
The meta objects that compose a meta type are accessed in the following ways:
Meta constructors. They are accessed by types of arguments:
The returned type is ctor and may be invalid if there is no constructor that
accepts the supplied arguments or at least some types from which they are
derived or to which they can be converted.
A meta constructor offers an API to know the number of arguments, the expected
meta types and to invoke it, therefore to construct a new instance of the
underlying type.
Meta destructor. It’s returned by a dedicated function:
The returned type is dtor and may be invalid if there is no custom
destructor set for the given meta type.
All what a meta destructor has to offer is a way to invoke it on a given
instance. Be aware that the result may not be what is expected.
Meta data. They are accessed by name:
meta::data data = meta::resolve<my_type>().data(hash("member"));
The returned type is data and may be invalid if there is no meta data object
associated with the given identifier.
A meta data object offers an API to query the underlying type (ie to know if
it’s a const or a static one), to get the meta type of the variable and to set
or get the contained value.
The returned type is func and may be invalid if there is no meta function
object associated with the given identifier.
A meta function object offers an API to query the underlying type (ie to know
if it’s a const or a static function), to know the number of arguments, the
meta return type and the meta types of the parameters. In addition, a meta
function object can be used to invoke the underlying function and then get the
return value in the form of meta any object.
Meta bases. They are accessed through the name of the base types:
meta::base base = meta::resolve<derived_type>().base(hash("base"));
The returned type is base and may be invalid if there is no meta base object
associated with the given identifier.
Meta bases aren’t meant to be used directly, even though they are freely
accessible. They expose only a few methods to use to know the meta type of the
base class and to convert a raw pointer between types.
Meta conversion functions. They are accessed by type:
The returned type is conv and may be invalid if there is no meta conversion
function associated with the given type.
The meta conversion functions are as thin as the meta bases and with a very
similar interface. The sole difference is that they return a newly created
instance wrapped in a meta any object when they convert between different
types.
All the objects thus obtained as well as the meta types can be explicitly
converted to a boolean value to check if they are valid:
Furthermore, all meta objects with the exception of meta destructors can be
iterated through an overload that accepts a callback through which to return
them. As an example:
A meta type can also be used to construct or destroy actual instances of the
underlying type.
In particular, the construct member function accepts a variable number of
arguments and searches for a match. It returns a any object that may or may
not be initialized, depending on whether a suitable constructor has been found
or not. On the other side, the destroy member function accepts instances of
any as well as actual objects by reference and invokes the registered
destructor if any.
Be aware that the result of a call to destroy may not be what is expected. The
purpose is to give users the ability to free up resources that require special
treatment and not to actually destroy instances.
Meta types and meta objects in general contain much more than what is said: a
plethora of functions in addition to those listed whose purposes and uses go
unfortunately beyond the scope of this document.
I invite anyone interested in the subject to look at the code, experiment and
read the official documentation to get the best out of this powerful tool.
Policies: the more, the less
Policies are a kind of compile-time directives that can be used when recording
reflection information.
Their purpose is to require slightly different behavior than the default in some
specific cases. For example, when reading a given data member, its value is
returned wrapped in a any object which, by default, makes a copy of it. For
large objects or if the caller wants to access the original instance, this
behavior isn’t desirable. Policies are there to offer a solution to this and
other problems.
There are a few alternatives available at the moment:
The as-is policy, associated with the type meta::as_is_t.
This is the default policy. In general, it should never be used explicitly,
since it’s implicitly selected if no other policy is specified.
In this case, the return values of the functions as well as the properties
exposed as data members are always returned by copy in a dedicated wrapper and
therefore associated with their original meta types.
The as-void policy, associated with the type meta::as_void_t.
Its purpose is to discard the return value of a meta object, whatever it is,
thus making it appear as if its type were void.
If the use with functions is obvious, it must be said that it’s also possible
to use this policy with constructors and data members. In the first case, the
constructor will be invoked but the returned wrapper will actually be empty.
In the second case, instead, the property will not be accessible for
reading.
The as-alias policy, associated with the type meta::as_alias_t
It allows to build wrappers that act as aliases for the objects used to
initialize them. Modifying the object contained in the wrapper for which the
aliasing was requested will make it possible to directly modify the instance
used to initialize the wrapper itself.
This policy works with constructors (for example, when objects are taken from
an external container rather than created on demand), data members and
functions in general (as long as their return types are lvalue references).
Some uses are rather trivial, but it’s useful to note that there are some less
obvious corner cases that can in turn be solved with the use of policies.
Named constants and enums
A special mention should be made for constant values and enums. It wouldn’t be
necessary, but it will help distracted readers.
As mentioned, the data member function can be used to reflect constants of any
type among the other things.
This allows users to create meta types for enums that will work exactly like any
other meta type built from a class. Similarly, arithmetic types can be enriched
with constants of special meaning where required.
Personally, I find it very useful not to export what is the difference between
enums and classes in C++ directly in the space of the reflected types.
All the values thus exported will appear to users as if they were constant data
members of the reflected types.
Exporting constant values or elements from an enum is as simple as ever:
It goes without saying that accessing them is trivial as well. It’s a matter of
doing the following, as with any other data member of a meta type:
my_enum value = meta::resolve<my_enum>().data(hash("a_value")).get({}).cast<my_enum>();
int max = meta::resolve<int>().data(hash("max_int")).get({}).cast<int>();
As a side note, remember that all this happens behind the scenes without any
allocation because of the small object optimization performed by the meta any
class.
Properties and meta objects
Sometimes (for example, when it comes to creating an editor) it might be useful
to be able to attach properties to the meta objects created. Fortunately, this
is possible for most of them.
To attach a property to a meta object, no matter what as long as it supports
properties, it is sufficient to provide an object at the time of construction
such that std::get<0> and std::get<1> are valid for it. In other terms, the
properties are nothing more than key/value pairs users can put in an
std::pair. As an example:
The meta objects that support properties offer then a couple of member functions
named prop to iterate them at once and to search a specific property by key:
// iterate all the properties of a meta type
meta::resolve<my_type>().prop([](meta::prop prop) {
// ...
});
// search for a given property by name
meta::prop prop = meta::resolve<my_type>().prop(hash("tooltip"));
Meta properties are objects having a fairly poor interface, all in all. They
only provide the key and the value member functions to be used to retrieve
the key and the value contained in the form of meta any objects, respectively.
Unregister types
A type registered with the reflection system can also be unregistered. This
means unregistering all its data members, member functions, conversion functions
and so on. However, the base classes won’t be unregistered, since they don’t
necessarily depend on it. Similarly, implicitly generated types (as an example,
the meta types implicitly generated for function parameters when needed) won’t
be unregistered.
To unregister a type, users can use the unregister function from the global
namespace:
meta::unregister<my_type>();
This function returns a boolean value that is true if the type is actually
registered with the reflection system, false otherwise.
The type can be re-registered later with a completely different name and form.
Contributors
Requests for features, PR, suggestions ad feedback are highly appreciated.
If you find you can help me and want to contribute to the project with your
experience or you do want to get part of the project for some other reasons,
feel free to contact me directly (you can find the mail in the
profile).
I can’t promise that each and every contribution will be accepted, but I can
assure that I’ll do my best to take them all seriously.
If you decide to participate, please see the guidelines for
contributing before to create issues or pull
requests.
Take also a look at the
contributors list to
know who has participated so far.
License
Code and documentation Copyright (c) 2018-2019 Michele Caini.