optional | style extensions and reference support | Reactive Programming library
kandi X-RAY | optional Summary
kandi X-RAY | optional Summary
Single header implementation of std::optional with functional-style extensions and support for references.
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Currently covering the most popular Java, JavaScript and Python libraries. See a Sample of optional
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optional Examples and Code Snippets
Lines of Code : 14
License : No License
Copymeta = self._download_json(url, video_id)
{
...
"summary": "some fancy summary text",
...
}
description = meta.get('summary') # correct
description = meta['summary'] # incorrect
description = self._search_regex(
r']+id="titl def _enable_get_next_as_optional(strategy, dataset, cardinality):
"""Returns whether to enable using partial batch handling."""
# TODO(b/133073708): we currently need a flag to control the usage because
# there is a performance difference betwe def _convert_optional_get_value(pfor_input):
handle = pfor_input.stacked_input(0)
output_types = pfor_input.get_attr("output_types")
original_output_shapes = pfor_input.get_attr("output_shapes")
output_shapes = []
for shape in original_outp def _create_none_optionals(func_graph, n):
"""Creates `n` `None` optionals in func_graph.
Args:
func_graph: FuncGraph.
n: `int` the number of `None` optionals to make.
Returns:
A list of tensors in func_graph.
"""
with func_gr Community Discussions
Trending Discussions on optional
QUESTION
Is it possible to install Vue 3, but still do things the "Vue 2" way? In other words, I see that Vue 3 has the new Composition API, but is that optional or the required way of doing things in Vue 3?
For some reason, I was thinking that Vue 3 still allowed you to do things the Vue-2 way, using the Options API instead. Is that not the case? Thanks.
...ANSWER
Answered 2022-Mar-07 at 03:01Vue 3 does not require using the Composition API. The Options API is still available and will not be removed, as explained by two Vue core team members:
Thorsten Lünborg in Vue 3: Data down, Events up (19-MAY-2020):
IMPORTANT: The composition API is additive, it’s a new feature, but it doesn’t and will not replace the good ole “Options API” you know and love from Vue 1 and 2. Just consider this new API as another tool in your toolbox that may come in handy in certain situations that feel a little clumsy to solve with the Options API.
Ben Hong in Enjoy the Vue #48: "New in Vue 3: The Composition API" (19-JAN-2021):
[00:01:03]T: Yeah. Well, the first thing I remember hearing was that it was replacing the options API.
[00:01:08]BH: Big disclaimer. That isn’t happening. Big disclaimer.
...
[00:09:10]BH: [...] this is not something you need to go and rewrite your app in. [...] the composition API is not like, drop the options do composition. It's an additive thing that when you have a problem that it can solve, it's really great for that.
An early RFC for the Composition API had only considered deprecating the Options API:
A previous draft of this RFC indicated that there is the possibility of deprecating a number of 2.x options in a future major release, which has been redacted based on user feedback.
The Vue docs also confirm this:
Will Options API be deprecated?No, we do not have any plan to do so. Options API is an integral part of Vue and the reason many developers love it. We also realize that many of the benefits of Composition API only manifest in larger-scale projects, and Options API remains a solid choice for many low-to-medium-complexity scenarios.
QUESTION
Constructor injection of a logger into Startup works in earlier versions of ASP.NET Core because a separate DI container is created for the Web Host. As of now only one container is created for Generic Host, see the breaking change announcement.
Startup.cs
ANSWER
Answered 2021-Oct-05 at 16:00If you are using NLog the easiest way to log in you startup.cs is to add private property.
QUESTION
[I ran into the issues that prompted this question and my previous question at the same time, but decided the two questions deserve to be separate.]
The docs describe using destructuring assignment with my and our variables, but don't mention whether it can be used with has variables. But Raku is consistent enough that I decided to try, and it appears to work:
ANSWER
Answered 2022-Feb-10 at 18:47This is currently a known bug in Rakudo. The intended behavior is for has to support list assignment, which would make syntax very much like that shown in the question work.
I am not sure if the supported syntax will be:
QUESTION
C++23 std::optional is finally getting some very useful additions.
Since my knowledge of FP is very primitive I am wondering what is the syntax for the following two operations(that according to my googling are 2 basic monadic operations):
- monadic bind
- monadic return
My best guesses are:
monadic bind is transform
monadic return is just C++17 std::optional constructor(8)
ANSWER
Answered 2022-Jan-06 at 16:58Not quite.
In Haskell syntax, bind is of the form m a -> (a -> m b) -> m b, which corresponds to satisfying this concept (for all A, B, F)
QUESTION
It seems that SSL connection is required to use MySQL Workbench, and I don't think this is the case with previous versions.
I remember SSL connections used to be optional. After I updated it, all options are locked to require SSL.
How do I bypass this? I'm just a student and setting up SSL is out of my reach.
...ANSWER
Answered 2021-Nov-02 at 19:29I don't know if it may be the right approach for you, but what I did is downgrade my version of MySQL Workbench to 6.3 and uninstalled the previous version and it will then give you the "if available" option for SSL. As you are right, it is not the case for previous versions, however you do lose a few more modern features in the process.
https://downloads.mysql.com/archives/workbench/
Another solution as well is to connect to connect to the database in 6.3 and since the configuration saves are in same location, upgrade to 8.0 where it will still have the old configuration file and won't use SSL due to backwards compatibility.
QUESTION
I'm trying to use a function with a parameter of namedTuple which has default values. I tried this. Is that somehow possible?
...ANSWER
Answered 2021-Dec-21 at 02:46Rename your print() function, first you're using the built-in function name print which is bad style, secondly then you make a recursive call to print() inside print() (and I'm sure you meant to call the actual built-in print() inside function's body).
Second, use collection.namedtuple class to implement actual type of tuple, like following:
Also type annotations are not needed.
QUESTION
the below method compiles without problems:
...ANSWER
Answered 2021-Dec-21 at 14:14Compatibility with the return type Stream> in the first case is not obtained by virtue of numbers.map(Optional::of) returning a Stream> on its own; it's the compiler inferring the return type of numbers.map(...) due to it being a generic method:
QUESTION
Last week, I had a discussion with a colleague in understanding the documentation of C++ features on cppreference.com. We had a look at the documentation of the parameter packs, in particular the meaning of the (optional) marker:
(Another example can be found here.)
I thought it means that this part of the syntax is optional. Meaning I can omit this part in the syntax, but it is always required to be supported by the compiler to comply with the C++ standard. But he stated that it means that it is optional in the standard and that a compiler does not need to support this feature to comply to the standard. Which is it? Both of these explanations make sense to me.
I couldn't find any kind of explanation on the cppreference web site. I also tried to google it but always landed at std::optional...
ANSWER
Answered 2021-Aug-21 at 20:22It means that particular token is optional. For instance both these declarations work:
QUESTION
Some ranges adaptors such as filter_view, take_while_view and transform_view use std::optional's cousin copyable-box to store the callable object:
ANSWER
Answered 2021-Oct-09 at 14:20All the algorithms require copy-constructible function objects, and views are basically lazy algorithms.
Historically, when these adaptors were added, views were required to be copyable, so we required the function objects to be copy_constructible (we couldn't require copyable without ruling out captureful lambdas). The change to make view only require movable came later.
It is probably possible to relax the restriction, but it will need a paper and isn't really high priority.
QUESTION
To the internal content of an optional, doesn't the optional require placement new in order to reconstruct the internal in place storage or union? Is there some new feature like placement new in C++ 20 that allows for constexpr assignment of std::optional?
...ANSWER
Answered 2021-Dec-26 at 03:03To the internal content of an optional, doesn't the optional require placement new in order to reconstruct the internal in place storage or union?
For assignment, yes it does.
But while we still cannot do actual placement new during constexpr time, we did get a workaround for its absence: std::construct_at (from P0784). This is a very limited form of placement new, but it's enough to get optional assignment working.
The other change was that we also needed to be able to actually change the active member of a union - since it wouldn't matter if we could construct the new object if we couldn't actually switch. That also happened in C++20 (P1330).
Put those together, and you get a functional implementation of optional assignment: P2231. An abbreviated implementation would look like this:
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