var: add GIT_SEQUENCE_EDITOR variable

From: Sean Allred <[email protected]>

Provides the same benefits to scripts as exposing GIT_EDITOR, but allows distinguishing the 'sequence' editor from the 'core' editor.

See also 44fcb4977cbae67f4698306ccfe982420ceebcbf.

---
var: add GIT_SEQUENCE_EDITOR variable

In my case, I'm overriding the sequence editor in git rebase -i to do some pre-processing on the todo file, but I'd still like to open up the editor for further manipulation/verification of the todo steps. Just using GIT_EDITOR here will clobber folks' expectations that their custom-built sequence editor pops up (e.g. VSCode or Git Cola).

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1424%2Fvermiculus%2Fsa%2Fgit-var-sequence-editor-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1424/vermiculus/sa/git-var-sequence-editor-v1
Pull-Request: https://github.com/gitgitgadget/git/pull/1424

 Documentation/git-var.txt |  7 +++++++
 builtin/var.c             | 11 +++++++++++
 t/t0007-git-var.sh        | 38 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 56 insertions(+)

index 6aa521fab23..764a94b2a1f 100644
@@ -49,6 +49,13 @@ ifdef::git-default-editor[]
     The build you are using chose '{git-default-editor}' as the default.
 endif::git-default-editor[]
 
+GIT_SEQUENCE_EDITOR::
+    Text editor for use by Git sequencer commands. Like `GIT_EDITOR`,
+    the value is meant to be interpreted by the shell when it is used.
+    The order of preference is the `$GIT_SEQUENCE_EDITOR` environment
+    variable, then `sequence.editor` configuration, and then the value
+    of `git var GIT_EDITOR`.
+
 GIT_PAGER::
     Text viewer for use by Git commands (e.g., 'less').  The value
     is meant to be interpreted by the shell.  The order of preference

index 491db274292..9a2d31dc4aa 100644
@@ -19,6 +19,16 @@ static const char *editor(int flag)
 	return pgm;
 }
 
+static const char *sequence_editor(int flag)
+{
+	const char *pgm = git_sequence_editor();
+
+	if (!pgm && flag & IDENT_STRICT)
+		die("Terminal is dumb, but EDITOR unset");
+
+	return pgm;
+}
+
 static const char *pager(int flag)
 {
 	const char *pgm = git_pager(1);

@@ -41,6 +51,7 @@ static struct git_var git_vars[] = {
 	{ "GIT_COMMITTER_IDENT", git_committer_info },
 	{ "GIT_AUTHOR_IDENT",   git_author_info },
 	{ "GIT_EDITOR", editor },
+	{ "GIT_SEQUENCE_EDITOR", sequence_editor },
 	{ "GIT_PAGER", pager },
 	{ "GIT_DEFAULT_BRANCH", default_branch },
 	{ "", NULL },

index e56f4b9ac59..3199285fa7b 100755
@@ -47,6 +47,44 @@ test_expect_success 'get GIT_DEFAULT_BRANCH with configuration' '
 	)
 '
 
+test_expect_success 'get GIT_SEQUENCE_EDITOR without configuration' '
+	(
+		sane_unset GIT_SEQUENCE_EDITOR &&
+		git var GIT_EDITOR >expect &&
+		git var GIT_SEQUENCE_EDITOR >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get GIT_SEQUENCE_EDITOR with configuration' '
+	test_config sequence.editor foo &&
+	(
+		sane_unset GIT_SEQUENCE_EDITOR &&
+		echo foo >expect &&
+		git var GIT_SEQUENCE_EDITOR >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get GIT_SEQUENCE_EDITOR with environment variable' '
+	(
+		sane_unset GIT_SEQUENCE_EDITOR &&
+		echo bar >expect &&
+		GIT_SEQUENCE_EDITOR=bar git var GIT_SEQUENCE_EDITOR >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get GIT_SEQUENCE_EDITOR with configuration and environment variable' '
+	test_config sequence.editor foo &&
+	(
+		sane_unset GIT_SEQUENCE_EDITOR &&
+		echo bar >expect &&
+		GIT_SEQUENCE_EDITOR=bar git var GIT_SEQUENCE_EDITOR >actual &&
+		test_cmp expect actual
+	)
+'
+
 # For git var -l, we check only a representative variable;
 # testing the whole output would make our test too brittle with
 # respect to unrelated changes in the test suite's environment.

base-commit: a0789512c5a4ae7da935cd2e419f253cb3cb4ce7

gitgitgadget

Why should we ;-)?

If you explain why "git var GIT_SEQUENCE_EDITOR" is useful in a more direct way, you do not even have to refer to a long hexadecimal string which by itself does not mean anything to sane human beings.

The editor program used by Git when editing the sequencer "todo" file is determined by examining a few environment variables and also affected by configuration variables. Introduce "git var GIT_SEQUENCE_EDITOR" that gives users an access to the final result of the logic without having to know the exact detail.

This is very similar in spirit to 44fcb497 (Teach git var about GIT_EDITOR, 2009-11-11) that introduced "git var GIT_EDITOR".

or something like that, perhaps?

I must admit I struggled quite a bit with a useful commit message, so I greatly appreciate the suggestion :-) I've incorporated your suggestion for a future v2.

That's a good point; I hadn't considered that as a potential source of confusion -- prefering instead to future-proof the docs at the cost of understandability :-)

I've incorporated your suggestion. It's possibly worth noting that I had wanted to prefer prose ('interactive rebase') over a specific invocation ('git rebase -i'), but I see existing precedent for referring to it as the latter in documentation (and release notes especially). I suppose this practice is intended (either consciously or otherwise) to make it more straightforward to cross-reference different pieces of the documentation?

I'm glad you brought this up. To be perfectly honest, I'm not confident I know what IDENT_STRICT is even supposed to mean -- it looks to be undocumented in cache.h. Here's what I *think* I've been able to piece together based on what you've said and some commit history:

f9bc573fdaeaf8621008f3f49aaaa64869791691 suggests that setting IDENT_STRICT is intended to be 'more upset' about 'things' (the commit I mention is specifically talking about identities -- which explains the IDENT_* prefix) that aren't well-defined. In porcelain code, we want to quit immediately if there's nothing available since you can't really open up COMMIT_MSG, e.g., without a well-defined editor. Better to die early with a semi-useful message than to let the issue propagate downstream.

This does not apply to git-var since the purpose of this command is not to invoke an editor, but to inspect configuration state via well-defined API. In this context, it's not necessary/appropriate to die early since, for the purposes of git-var, 'no configuration' is a perfectly valid (albeit confusing) state to be in.

I'd like to confirm this / understand more about what's going on here before making the code change on this one. If I can understand what's going on here well enough to write an informed commit message, I can remove this vestigial code from editor() in a separate patch.

--
Sean Allred

From: Sean Allred <[email protected]>

The editor program used by Git when editing the sequencer "todo" file is determined by examining a few environment variables and also affected by configuration variables. Introduce "git var GIT_SEQUENCE_EDITOR" to give users access to the final result of the logic without having to know the exact details.

This is very similar in spirit to 44fcb497 (Teach git var about GIT_EDITOR, 2009-11-11) that introduced "git var GIT_EDITOR".

---
var: add GIT_SEQUENCE_EDITOR variable

In my case, I'm overriding the sequence editor in git rebase -i to do some pre-processing on the todo file, but I'd still like to open up the editor for further manipulation/verification of the todo steps. Just using GIT_EDITOR here will clobber folks' expectations that their custom-built sequence editor pops up (e.g. VSCode or Git Cola).

Changes since v1:

* rebased on current main
* following new, simplified patterns from my previous pull-request merged in d8184580

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1424%2Fvermiculus%2Fsa%2Fgit-var-sequence-editor-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1424/vermiculus/sa/git-var-sequence-editor-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/1424

Range-diff vs v1:

1: aa5ac73ab39 ! 1: c9683fabf3d var: add GIT_SEQUENCE_EDITOR variable
@@ Metadata
## Commit message ##
var: add GIT_SEQUENCE_EDITOR variable

- Provides the same benefits to scripts as exposing GIT_EDITOR, but
- allows distinguishing the 'sequence' editor from the 'core' editor.
+ The editor program used by Git when editing the sequencer "todo" file
+ is determined by examining a few environment variables and also
+ affected by configuration variables. Introduce "git var
+ GIT_SEQUENCE_EDITOR" to give users access to the final result of the
+ logic without having to know the exact details.

- See also 44fcb4977cbae67f4698306ccfe982420ceebcbf.
+ This is very similar in spirit to 44fcb497 (Teach git var about
+ GIT_EDITOR, 2009-11-11) that introduced "git var GIT_EDITOR".

@@ Documentation/git-var.txt: ifdef::git-default-editor[]
endif::git-default-editor[]

+GIT_SEQUENCE_EDITOR::
-+ Text editor for use by Git sequencer commands. Like GIT_EDITOR,
-+ the value is meant to be interpreted by the shell when it is used.
-+ The order of preference is the $GIT_SEQUENCE_EDITOR environment
-+ variable, then sequence.editor configuration, and then the value
-+ of git var GIT_EDITOR.
++ Text editor used to edit the 'todo' file while running `git rebase
++ -i. Like GIT_EDITOR`, the value is meant to be interpreted by
++ the shell when it is used. The order of preference is the
++ $GIT_SEQUENCE_EDITOR environment variable, then
++ sequence.editor configuration, and then the value of `git var
++ GIT_EDITOR`.
+
GIT_PAGER::
Text viewer for use by Git commands (e.g., 'less'). The value
@@ Documentation/git-var.txt: ifdef::git-default-editor[]

## builtin/var.c ##
@@ builtin/var.c: static const char *editor(int flag)
- return pgm;
+ return git_editor();
}

+static const char *sequence_editor(int flag) +{
-+ const char *pgm = git_sequence_editor();
-+
-+ if (!pgm && flag & IDENT_STRICT)
-+ die("Terminal is dumb, but EDITOR unset");
-+
-+ return pgm;
++ return git_sequence_editor();
+}
+
static const char *pager(int flag)
@@ builtin/var.c: static struct git_var git_vars[] = {
{ "", NULL },

## t/t0007-git-var.sh ##
-@@ t/t0007-git-var.sh: test_expect_success 'get GIT_DEFAULT_BRANCH with configuration' ' +@@ t/t0007-git-var.sh: test_expect_success 'get GIT_EDITOR with configuration and environment variable
)
'

 Documentation/git-var.txt |  8 ++++++++
 builtin/var.c             |  6 ++++++
 t/t0007-git-var.sh        | 38 ++++++++++++++++++++++++++++++++++++++
 3 files changed, 52 insertions(+)

index 0ab5bfa7d72..f40202b8e3a 100644
@@ -50,6 +50,14 @@ ifdef::git-default-editor[]
     The build you are using chose '{git-default-editor}' as the default.
 endif::git-default-editor[]
 
+GIT_SEQUENCE_EDITOR::
+    Text editor used to edit the 'todo' file while running `git rebase
+    -i`. Like `GIT_EDITOR`, the value is meant to be interpreted by
+    the shell when it is used. The order of preference is the
+    `$GIT_SEQUENCE_EDITOR` environment variable, then
+    `sequence.editor` configuration, and then the value of `git var
+    GIT_EDITOR`.
+
 GIT_PAGER::
     Text viewer for use by Git commands (e.g., 'less').  The value
     is meant to be interpreted by the shell.  The order of preference

index a1a2522126f..a80c1df86fd 100644
@@ -14,6 +14,11 @@ static const char *editor(int flag)
 	return git_editor();
 }
 
+static const char *sequence_editor(int flag)
+{
+	return git_sequence_editor();
+}
+
 static const char *pager(int flag)
 {
 	const char *pgm = git_pager(1);

@@ -36,6 +41,7 @@ static struct git_var git_vars[] = {
 	{ "GIT_COMMITTER_IDENT", git_committer_info },
 	{ "GIT_AUTHOR_IDENT",   git_author_info },
 	{ "GIT_EDITOR", editor },
+	{ "GIT_SEQUENCE_EDITOR", sequence_editor },
 	{ "GIT_PAGER", pager },
 	{ "GIT_DEFAULT_BRANCH", default_branch },
 	{ "", NULL },

index 433d242897c..eeb8539c1bc 100755
@@ -109,6 +109,44 @@ test_expect_success 'get GIT_EDITOR with configuration and environment variable
 	)
 '
 
+test_expect_success 'get GIT_SEQUENCE_EDITOR without configuration' '
+	(
+		sane_unset GIT_SEQUENCE_EDITOR &&
+		git var GIT_EDITOR >expect &&
+		git var GIT_SEQUENCE_EDITOR >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get GIT_SEQUENCE_EDITOR with configuration' '
+	test_config sequence.editor foo &&
+	(
+		sane_unset GIT_SEQUENCE_EDITOR &&
+		echo foo >expect &&
+		git var GIT_SEQUENCE_EDITOR >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get GIT_SEQUENCE_EDITOR with environment variable' '
+	(
+		sane_unset GIT_SEQUENCE_EDITOR &&
+		echo bar >expect &&
+		GIT_SEQUENCE_EDITOR=bar git var GIT_SEQUENCE_EDITOR >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'get GIT_SEQUENCE_EDITOR with configuration and environment variable' '
+	test_config sequence.editor foo &&
+	(
+		sane_unset GIT_SEQUENCE_EDITOR &&
+		echo bar >expect &&
+		GIT_SEQUENCE_EDITOR=bar git var GIT_SEQUENCE_EDITOR >actual &&
+		test_cmp expect actual
+	)
+'
+
 # For git var -l, we check only a representative variable;
 # testing the whole output would make our test too brittle with
 # respect to unrelated changes in the test suite's environment.

base-commit: 57e2c6ebbe7108b35ba30184dcbcb6c34c929ad8

gitgitgadget