Support multi-compiler

[lenqwang]

Support multi-compiler from issue #237

When the poi dev command encounters multiple compilers, there are two solutions

• Solution A:

If there are more than one compiler, this PR will take the 1st one as the processing object

• Solution B:

If there are more than one compiler, this PR will terminate and prompt the error message to the user

Now this PR apply Solution A
I don't know how to deal with the more appropriate, please give a feedback

[egoist]

In which case the compiler would be a MultiCompiler?

[lenqwang]

Yeah! If not this PR will do nothing

[egoist]

so why do we need this PR? this.compiler always only contains a single compiler

[lenqwang]

As issue #237 When webpack config is return a multi configs

[egoist]

@qqcome110 Ah I see

[egoist]

Hmm,

If there are more than one compiler, this PR will take the 1st one as the processing object

So why do you return an array of webpack configs in webpack(config) {} in the first place? It only uses the first compiler anyways regarding your PR.

[lenqwang]

When you run poi dev will do this, But poi build & poi watch will be not

[egoist]

they actually should have consistent behavior IMO.

[lenqwang]

You mean that they are all return 1st one compiler?

[egoist]

I don't get it, why do you return multi webpack config and only use the first one.

[lenqwang]

I get your mean, If return multi webpack config can weigh whether to support multiple servers

[lenqwang]

webpack/webpack#1849
webpack/webpack-dev-middleware#151

[allenfantasy]

IMO the main problem of this issue would be: currently Poi could not support multi compiler. And the PR just solve this problem, but we need to confirm:

how Poi should deal with multiple compilers in dev mode

And since webpack-dev-server has already support a multiple compiler config (see the comment here which points out that this PR has solved the problems), IMO we should create multiple webpack-dev-server instances but I haven't got time to verify this theory.

cc @qqcome110

[allenfantasy]

Any ideas about this PR? @egoist