Subject: Re: [PATCH v2] diff: support anchoring line(s)

From: Junio C Hamano <[email-masked]>
Date: Tue, 28 Nov 2017 10:38:48 +0900

Jonathan Tan <[email-masked]> writes:

> -	else if (!strcmp(arg, "--patience"))
> +	else if (!strcmp(arg, "--patience")) {
> +		int i;
>  		options->xdl_opts = DIFF_WITH_ALG(options, PATIENCE_DIFF);
> -	else if (!strcmp(arg, "--histogram"))
> +		/*
> +		 * Both --patience and --anchored use PATIENCE_DIFF
> +		 * internally, so remove any anchors previously
> +		 * specified.
> +		 */
> +		for (i = 0; i < options->anchors_nr; i++)
> +			free(options->anchors[i]);
> +		options->anchors_nr = 0;

This makes sense, but "--diff-algorithm=patience" would want to do
the same, I suspect, so the loop would want to become a little
helper function "clear_patience_anchors(options)" or something like
that.

> diff --git a/t/t4064-diff-anchored.sh b/t/t4064-diff-anchored.sh
> new file mode 100755
> index 000000000..b3f510f04
> --- /dev/null
> +++ b/t/t4064-diff-anchored.sh
> @@ -0,0 +1,94 @@
> +#!/bin/sh
> +
> +test_description='anchored diff algorithm'
> +
> +. ./test-lib.sh
> +
> +test_expect_success '--anchored' '
> +	printf "a\nb\nc\n" >pre &&
> +	printf "c\na\nb\n" >post &&

This may be too little to matter, but I'd find

	printf "%s\n" a b c >pre

vastly easier to read.  Or perhaps just use

	test_write_lines a b c >pre