Code examples of plugins

[Booker Bense]

My project elixgrep has the ability to use plugins, but I'm not very happy with the way it works. 

It basically reads the plugin name from the cmd line and recompiles and swaps in a new version 

of an existing module. 

I'm pretty sure Behaviours is where I want to start, but I was wondering if there are code examples out

there of how to load code at run time and call function X from that module.  

thanks 

- Booker C. Bense 

[Vincent Siliakus]

Not an actual example, but assuming that a plugin is a single file, I think Code.load_file/2 would be best suited for this.

I'm not sure if behaviours will help ensuring that a plugin/module exports the expected functions, because when a module fails to correctly implement a behaviour, the compiler just emits a warning, that you, afaik, can't catch when calling Code.load_file/2. An alternative would be using MyPlugin.__info__(:functions) and check if the module exports the expected functions.

-vincent

[Booker Bense]

On Tuesday, April 14, 2015 at 2:49:28 AM UTC-7, Vincent Siliakus wrote:

Not an actual example, but assuming that a plugin is a single file, I think Code.load_file/2 would be best suited for this

I'm currently using Code.require_file. 

 

I'm not sure if behaviours will help ensuring that a plugin/module exports the expected functions, because when a module fails to correctly implement a behaviour, the compiler just emits a warning, that you, afaik, can't catch when calling Code.load_file/2. An alternative would be using MyPlugin.__info__(:functions) and check if the module exports the expected functions.

I think Mix.Tasks provides most of what I'm looking for as an example. I was mostly interested in how you go from 

a string to a Module that you can query. What I do currently is have each plugin simply reimplement the same Module. 

- Booker C. Bense 

[José Valim]

Doesn't Code.require_file returns the modules that were loaded in the file? If so, you can use this information to find out which modules were defined. Then you could traverse them looking up for some module that implements your particular function with function_exported?/3 and fail if you got none or more than one.

José Valim

www.plataformatec.com.br

Skype: jv.ptec

Founder and Lead Developer

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[Booker Bense]

On Tuesday, April 14, 2015 at 2:10:54 PM UTC-7, José Valim wrote:

Doesn't Code.require_file returns the modules that were loaded in the file? If so, you can use this information to find out which modules were defined. Then you could traverse them looking up for some module that implements your particular function with function_exported?/3 and fail if you got none or more than one.

Yes, that's exactly what I need to do. I was just hoping that someone had already done the dirty work for me... 

- Booker C. Bense 

[Booker Bense]

I have implemented a first pass at this in 

https://github.com/bbense/pluginator

Comments are welcome. 

- Booker C. Bense

[Gabriele Lana]

On Sun, Apr 19, 2015 at 7:14 PM, Booker Bense <bbe...@gmail.com> wrote:
> I have implemented a first pass at this in
>
> https://github.com/bbense/pluginator

That’s cool +1

> Comments are welcome.

Would be nice to have a function that loads every module that is
compliant with a signature in a directory

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Gabriele Lana
https://github.com/gabrielelana
https://twitter.com/gabrielelana

[Booker Bense]

On Monday, April 20, 2015 at 8:50:28 AM UTC-7, Gabriele Lana wrote:

Would be nice to have a function that loads every module that is
compliant with a signature in a directory

I can do load every .exs file in a directory and of those files return a list of the modules that

match a signature. However all the modules would be loaded, not just those that match. 

- Booker C. Bense 

[Gabriele Lana]

You can unload them :-) see code:delete and code:purge (if I remember correctly) in Erlang docs

 

- Booker C. Bense 

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