Improve gno run

[moul]

The gno run command is presently in a pre-alpha phase and may not perform reliably due to its specific requirements for package and function naming.

Its primary objective is to facilitate a smooth transition for developers from Go by allowing them to start with a basic main function. Additionally, it aims to provide utility tools for those who are forking or reviewing a package.

To enhance its usability and commence documentation in guides, two primary enhancements are urgently needed:

1. The inclusion of argument passing support akin to os.Args, enabling more dynamic results from a single main function based on various parameters.
2. Increased flexibility in the package PKGPATH specification, making it easier to add a main function and execute gno run on a package without having to specify a file (related to issue Allow *_test.gno file to run pkg with _test as suffix #768).

Addresses #972

[ajnavarro]

Starting with the implementation of the first enhancement (os.Args).

[ajnavarro]

I refactored the RunMain() method to accept a slice of arguments. Apart from that, I added the os package into the stdlibs gnovm folder.

stdlib is loaded when using VMKeeper but RunMain() is on the Machine struct, so it looks a bit strange that to make Args work, you need to use the VM through the VMKeeper.

I'm having some problems injecting the Args into a var inside a package, waiting for #859 which should make the process simpler.

If someone has some insights about how to move forward, I'd be willing to chat with you about it.

[moul]

Do you already have a PR for your work? can you share, the link?

[ajnavarro]

@moul I don't. Because I wasn't able to make it work, I just discarded the changes. I can recreate and add them to a draft PR.

[moul]

Yes please, a draft PR may be useful to help you.

[ajnavarro]

@moul This is what I was trying to do: #982

[salihdhaifullah]

I have a question how is the arguments will be parsed ?
currently when you try to pass arguments after/before the file name it will be treated as a file, for example when i run

gno run main.gno hello

I get stat hello: no such file or directory
how do you want to handle this, do you want to handle this using a flag for example

gno run main.gno  --args="Hello World"

or put the files under a flag

gno run  --files="main.gno test.gno" Hello World

[thehowl]

I discussed with @moul how to have os.Args in a "nice" way. Thanks for your contribution @salihdhaifullah, but actually direct access to os.Args is a non-goal.

Essentially we want main() as a way to access a realm / package from the GnoVM in an "interactive" way from the command line. There is already a way to have this - using gno run -expr, which allows to pass in an arbitrary expression to execute in place of main(); but we can "evolve" the usage of main to become a CLI "inspector" tool. Possibly in conjuction with #2989.

So, we're thinking of changing the functioning of gno run to be as follows:

gno run <PATH> [<ARGUMENT>...]

instead of supporting multiple file arguments.

Then, if arguments are passed, they are given in to the main function; in a fashion similar to what we have for maketx call. For example:

gno run . hello world

func main(arg1, arg2 string) {
    println(arg1, arg2)
}

will print hello world.