reducing compile time deps

[chungwong]

I have a few files are having their own module for sending out emails(modular structure)

lib/hello_world/a/email.ex
lib/hello_world/b/email.ex
lib/hello_world/c/email.ex
lib/hello_world/d/email.ex
...

All of those files contain

 use Phoenix.Swoosh, view: HelloWordWeb.EmailView, layout: {HelloWordWeb.LayoutView, :email}

Before removing use Phoenix.Swoosh, it would take

chung@debian:$ time mix compile
Compiling 33 files (.ex)

real	0m8.528s
user	0m19.535s
sys	0m0.990s

after removing use Phoenix.Swoosh

chung@debian:$ time mix compile
Compiling 24 files (.ex)

real	0m8.206s
user	0m16.695s
sys	0m0.888s

it would reduce the compile time by 1-2 seconds.

I tried to resort to put_layout/2 and put_view/2. However, use Phoenix.Swoosh requires a view to be defined, so
use Phoenix.Swoosh, view: HelloWordWeb.EmailView is the minimal requirement. With this change combined with put_layout, surprisingly the compile time didn't make a difference at all.

[princemaple]

The view is only kept as a name/alias, there is no function call on the view module so there shouldn't be any compile time dependency. Have you done any in-depth profiling & comparison?

[chungwong]

I haven't done any profiling(have no clue how to get it started).

However, the only comparison I have done was mentioned above(removing use Phoenix.Swoosh, view: HelloWordWeb.EmailView).

The compile time difference in my comparison could be because the compiling time actually fluctuated between 1-2 seconds. That is my pure guess though.

Does it mean although there is a compile time dependency, the overhead will be very very small? just like what behaviour is doing?

[princemaple]

The impact of compile time dependency is only about re-compilation. A compile time dependency causes extra recompilation when a dependency is changed. During a full compile, it makes no difference.