Subject: Re: [PATCH v2 2/4] ll-merge.c: refactor `read_merge_config()` to use `git_config_string()`

From: Junio C Hamano <[email-masked]>
Date: Wed, 13 Aug 2014 10:07:29 -0700

Tanay Abhra <[email-masked]> writes:

> There is one slight behavior change, previously "merge.default"
> silently ignored a NULL value and didn't raise any error. But,
> in the same function, all other values raise an error on a NULL
> value. So to conform with other call sites in Git, a NULL value
> for "merge.default" raises an error.

Better explained than v1 ;-)

> Signed-off-by: Tanay Abhra <[email-masked]>
> ---
> We cannot easily use the new config-set API here, because
> much of the function is dedicated to processing
> "merge.<name>.variable" which does not easily translate to
> the new API. If it were for variables like,
> "merge.summary", "merge.tool", and "merge.verbosity", we
> could use the new API.

I think this comment belongs to the log message, if only to serve as
a reminder for us that the API needs to be made more usable when the
caller wants to use these three-level names, which are quite common.
This code path knows the name of a low-level merge driver and wants
to learn everything about that driver.  Another code path may know
the name of the branch and may want to scan "branch.<name>.*".

>  ll-merge.c | 23 ++++++-----------------
>  1 file changed, 6 insertions(+), 17 deletions(-)
>
> diff --git a/ll-merge.c b/ll-merge.c
> index fb61ea6..8ea03e5 100644
> --- a/ll-merge.c
> +++ b/ll-merge.c
> @@ -225,11 +225,8 @@ static int read_merge_config(const char *var, const char *value, void *cb)
>  	const char *key, *name;
>  	int namelen;
>
> -	if (!strcmp(var, "merge.default")) {
> -		if (value)
> -			default_ll_merge = xstrdup(value);
> -		return 0;
> -	}
> +	if (!strcmp(var, "merge.default"))
> +		return git_config_string(&default_ll_merge, var, value);
>
>  	/*
>  	 * We are not interested in anything but "merge.<name>.variable";
> @@ -254,12 +251,8 @@ static int read_merge_config(const char *var, const char *value, void *cb)
>  		ll_user_merge_tail = &(fn->next);
>  	}
>
> -	if (!strcmp("name", key)) {
> -		if (!value)
> -			return error("%s: lacks value", var);
> -		fn->description = xstrdup(value);
> -		return 0;
> -	}
> +	if (!strcmp("name", key))
> +		return git_config_string(&fn->description, var, value);
>
>  	if (!strcmp("driver", key)) {
>  		if (!value)
> @@ -285,12 +278,8 @@ static int read_merge_config(const char *var, const char *value, void *cb)
>  		return 0;
>  	}
>
> -	if (!strcmp("recursive", key)) {
> -		if (!value)
> -			return error("%s: lacks value", var);
> -		fn->recursive = xstrdup(value);
> -		return 0;
> -	}
> +	if (!strcmp("recursive", key))
> +		return git_config_string(&fn->recursive, var, value);
>
>  	return 0;
>  }