Re: [boost-ext] DI questions

From: Andrzej Krzemienski (akrzemi1_at_[hidden])
Date: 2021-02-19 20:27:12

czw., 18 lut 2021 o 20:58 Krzysztof Jusiak via Boost <boost_at_[hidden]>
napisał(a):

> Hi,
>
> I just wanted to share, potentially useful for the Boost and C++ community,
> libraries and ask if anyone would be willing to become a Review Manager for
> any of them?
>
> [boost-ext] (https://github.com/boost-ext) is a collection of C++
> libraries
> with aspirations to be included in Boost. Libraries can be characterized
> by:
> * Modern C++ (>= C++14)
> * Header/Single Module only
> * No dependencies
>
> ATM, [boost::ext] consists of four core libraries:
>
> * DI - Dependency Injection Library
>     overview:
>       standard: C++14
>       single header with no dependencies (neither STL nor Boost is
> required)
>       release: 1.2.0 (first release - 2014)
>       key features:
>         - supports macro-free constructor injection
>         - supports templates injection
>         - quick compilation-times
>         - highly optimized code generation
>     try it online: https://godbolt.org/z/5qTKhf
>     source code: https://github.com/boost-ext/di
>     documentation: https://boost-ext.github.io/di/

Regarding the DI library, I read the introduction and the tutorial part,
and it does not help me understand what problem this library solves or why
I should use it. Is there some other way to explain what this library is
for?
Or maybe I need to switch my mindset to Java-like OO patterns a la GoF in
order to appreciate this?
Is there a lot of theory that I have to learn prior to be able to
understand what it is for?

The docs give this example:

auto injector = di::make_injector();
  injector.create<app>();

Does this create a temporary object of type `app` that vanishes
momentarily? Or is there some magical object lifetime management going on
behind the scenes?

Also, it looks like it will only work if the leaves of this dependency tree
are default-constructible and if I am happy with calling default
constructors. But usually I am not: I need to pass arguments to my objects,
even if they are leaves in the dependency tree.

I would appreciate help in understanding the motivation.

Regards,
&rzej;

>
>
> * SML - State Machine Library
>     overview:
>       standard: C++14
>       single header with no dependencies (neither STL nor Boost is
> required)
>       release: 1.1.4 (first release - 2016)
>       key features:
>         - much faster compilation-times than Boost.MSM (up to 60x faster)
>         - highly optimized and customizable code generation
>         - suitable for embedded systems
>     try it online: https://godbolt.org/z/y99L50
>     source code: https://github.com/boost-ext/sml
>     documentation: https://boost-ext.github.io/sml/
>
> * UT - Unit Testing Framework
>     overview:
>       standard: C++20
>       single header with no dependencies (STL required)
>       release: 1.1.8 (first release - 2019)
>       key features:
>         - macro-free
>         - minimal boilerplate
>         - fast compilation-times and execution
>     try it online: https://godbolt.org/z/Jqb5Ye
>     source code: https://github.com/boost-ext/ut
>     documentation: https://boost-ext.github.io/ut
>
> * TE - Run-time polymorphism (type erasure) library
>     overview:
>       standard: C++17
>       single header with no dependencies (STL required)
>       release: -
>       key features:
>         - simple interface
>         - highly optimized code generation
>     try it online: https://godbolt.org/z/xY9MEq
>     source code: https://github.com/boost-ext/te
>     documentation: https://github.com/boost-ext/te
>
> All libraries (except TE) were successfully deployed in the production
> systems.
> Some, such as DI and SML are used by well known/big IT companies as well.
>
> If anyone is interested in becoming a Review Manager for any of
> the libraries, I'd really appreciate it and I'll more than happy to address
> any issues/requests before the review as well as help with any
> process-related tasks.
>
> Thank you very much,
> -Kris
>
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