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From Michele Sciabarra <mich...@sciabarra.com>
Subject Re: Interpretation of "main" for GoLang and ActionLoop docker images
Date Mon, 01 Oct 2018 10:51:44 GMT
About  -main "foo.Bar" there are 2 problems doing that.

First thing, I need to "capitalize" the main function name.  So "--main main"  means "Main"
in package "main"

Why? Because In Go there is only one main in package main with signature "()" and I need to
use it for the "startup" code.

So I have use either another name or "main" another package. But if I use for example "main"
in another package... I have the problem that whatever function I use it must be capitalized
anyway because that is the Go way to say "public".  Initially it was "action.Main" the I decided
that just leaving in "main" package was fine no need to specify an arbitrary package. Also
because usually files in "main" package are left in the root while other packages are in subdirectories.

So the simplest solution it to interpret "main" as "main.Main" and "hello" and "main.Hello".

Is it possible to use "-main package.function" ? Well it is but... 

1. I would need to split "package" and "function" then capitalize to "Function" and interpret
as "package.Function" (because for sure Package.function is NOT going to work..."
2. in the startup code I do not have only to replace the function name but also add "import
"package"" somewhere.

Not sure it is worth the effort because it is pretty ease to write a function in main package
that will forward to whatever entry point in inner packages we may want.


If you have better ideas they are welcome.

-- 
  Michele Sciabarra
  michele@sciabarra.com

----- Original message -----
From: Rob Allen <rob@akrabat.com>
To: dev@openwhisk.apache.org
Subject: Re: Interpretation of "main" for GoLang and ActionLoop docker images
Date: Sun, 30 Sep 2018 21:38:49 +0100

Hi Michele,

>From a someone who doesn't use Go, this all seems sensible and predictable to me, though
I have one question that may show my lack of knowledge of the language!

> Case4: sending a zip with source actions. Here is where the current rules turned out
to be very confusing. So I am going to simplify this way:
> 
> You can upload all the files you want in your zip file, they must all have .go extension
and they will be compiled. You must NOT have a main.main function as this will be provided
by the runtime. The name of the main function will be interpreted as in 3: -main main (or
default) => main.Main , -main hello => main.Hello


Does this mean that I can't specify a different module other than main for entry point? e.g.
would  -main foo.Bar work and result in the Bar function in the foo package being the entry
point to the action?

This is on my mind as I'm considering updating the PHP (and Python?) runtimes to support setting
the file as well as the function name and would use the format -name foo.php:bar to run the
bar() function in foo.php as the entry point. (Currently, the filename is hardcoded to index.php).

Regards

Rob




> On 29 Sep 2018, at 09:03, Michele Sciabarra <michele@sciabarra.com> wrote:
> 
> Hello all,
> 
> I need to discuss my plan for simplifying rules for interpreting "main" for Golang. 
> 
> The rules I have used for interpreting the "main" parameter in wsk turned out to be a
bit confusing, so I plan to make them simpler. This is what I plan to implement, please confirm
it is fine OR tell me if there is something I should change. The text below will go in documentation
if it is ok.
> 
> ----
[snip]

-- 
Development thoughts at http://akrabat.com
Daily Jotter for macOS at http://dailyjotter.com


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