https://github.com/dlang-community/configy
An automatic YAML to struct configuration parser for dlang
https://github.com/dlang-community/configy
configuration dlang metaprogramming yaml
Last synced: 6 months ago
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An automatic YAML to struct configuration parser for dlang
- Host: GitHub
- URL: https://github.com/dlang-community/configy
- Owner: dlang-community
- License: mit
- Created: 2021-09-07T13:45:47.000Z (almost 5 years ago)
- Default Branch: v3.x.x
- Last Pushed: 2025-10-01T15:32:28.000Z (9 months ago)
- Last Synced: 2025-10-01T15:32:41.325Z (9 months ago)
- Topics: configuration, dlang, metaprogramming, yaml
- Language: D
- Homepage:
- Size: 307 KB
- Stars: 4
- Watchers: 6
- Forks: 5
- Open Issues: 6
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Configy: Simple, efficient YAML -> `struct` converter
## Why (would I use this) ?
Any decently-sized application needs to eventually be configured.
When an application's complexity is past the threshold where its options can be
managed by command line arguments alone, one need to add a configuration file.
Enter a myriad of questions:
- What format do I use ?
- How do I document it ?
- What are sensible default values ?
- How do I accurately report errors ?
And so on. This framework provide an opiniated answer to all those questions.
## How (do I use this) ?
Let's start with an hello world:
```D
module helloworld;
import configy.easy;
import std.stdio;
import std.typecons;
import core.thread;
struct Config
{
/// The name to greet
string name;
/// Other people to greet
SetInfo!(string[]) extra_names;
/// How often to greet the user
Duration frequency = 1.seconds;
/// How many times should we repeat the greeting (0: no limit)
@Optional size_t limit;
}
int main (string[] args)
{
// `parseConfigFileSimple` will print to `stderr` if an error happened
Nullable!Config configN = parseConfigFileSimple!Config("config.yaml");
if (configN.isNull())
return 1;
auto config = configN.get();
// Your program goes here
for (size_t i = 0; config.limit == 0 || i < config.limit; ++i)
{
writeln("Hello World to you ", config.name);
if (config.extra_names.set)
writefln("And to you too, %-(%s, %)", config.extra_names.value);
Thread.sleep(config.frequency);
}
return 0;
}
```
This code can be found [here](examples/helloworld/), along with the associated configuration:
```YAML
name: "Lord Commander Tenant"
extra_names:
- The Gary
- Mooncake
```
This demonstrate a few important properties of the config parser:
- Any field with an initializer (different from `.init`) is considered optional;
- Fields can be set to optional through to `Optional` UDA if their `init` value should be their default;
- Using `SetInfo` allows on to have optional fields that carry whether they were set or not;
- `Duration` is natively parsed;
## Full documentation
The full, up-to-date API documentation can be found [here](https://dlang-community.github.io/configy/).
A list of example for common use cases can be found [here](doc/FAQ.md).
## Rich error reporting
Because humans make mistakes, and configuration are aimed towards humans, special care is given to errors.
Using the [helloworld](examples/helloworld) example, here are some of the errors that would be reported:
```YAML
# Missing required option `name`
limit: 1
```
```YAML
# Wrong key: Should be `name`, not `username`
username: "Lord Commander Tenant"
```
This error is optional, but enabled by default. See `strict mode` in documentation.