Re: [PATCH v2 4/7] for-each-repo: run subcommands on configured repos

[Junio C Hamano <gitster@pobox.com>]

"Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com> writes:

> +SYNOPSIS
> +--------
> +[verse]
> +'git for-each-repo' --config=<config> [--] <arguments>
> + ...
> +--config=<config>::
> +	Use the given config variable as a multi-valued list storing
> +	absolute path names.

Would it make sense to allow this config to be read from the current
repository, I wonder.  It is probably designed to be written to
either ~/.gitconfig or /etc/gitconfig because it is probably a need
that is not per-repository to list repositories for various purposes
specified by the config key, but I suspect there _might_ be a good
use case for storing some custom list of repositories in the
configuration file local to a repository, but it is not quite
obvious what it is.

If we have a good example, we may want to spell it out---that would
help future readers who wonder about this (just like I am doing now).

Also, if we do read from local config, should there be a way to say
"ah, you may have read values from /etc/gitconfig and ~/.gitconfig,
but please forget them---I have a full list I care when you are
running in this repository", i.e. clear the list.  It is purely a
convention and there is no built-in mechanism for this in the config
API, but often it is signalled by giving an empty string as a value.

By the way, I do not have a good concrete suggestion, but can we use
something better than <config> as the placeholder?  I first thought
this was naming the name of a file that lists repositories, not the
config variable name in our usual config namespace.

> +static int run_command_on_repo(const char *path,
> +			       void *cbdata)

Is that on repo or in repo?  When I saw "-C" on the command line, I
immediately thought of "in repo".

> +{
> +	int i;
> +	struct child_process child = CHILD_PROCESS_INIT;
> +	struct strvec *args = (struct strvec *)cbdata;
> +
> +	child.git_cmd = 1;
> +	strvec_pushl(&child.args, "-C", path, NULL);
> +
> +	for (i = 0; i < args->nr; i++)
> +		strvec_push(&child.args, args->v[i]);

Would strvec_pushv() work, or is args->v[] not NULL terminated?

> +	return run_command(&child);
> +}


> +	values = repo_config_get_value_multi(the_repository,
> +					     config_key);

Not your fault, but it is a bit unsatisfactory that we do not have
special "type" meant for paths in the config API, unlike the
parse-options API where there is a "filename" type that is a bit
richer than a vanilla "string" type by allowing "prefix" handling.
For the purposes of this, as the values are limited to absolute/full
pathnames, it does not hurt as much, though.

Thanks.