Re: [PATCH] help.c: add a compatibility comment to cmd_version()
From: Junio C Hamano gits...@pobox.com Sent: Thursday, April 18, 2013 1:13 AM Philip Oakley philipoak...@iee.org writes: How about * E.g. git gui uses the extended regular expression ^git version [1-9]+(\.[0-9]+)+.* * to check for an acceptable version string. The ERE is from git-gui.sh:L958. That is exactly the kind of guarantee we do _not_ want to give. So you are trying to avoid giving _any_ guarantee about what visible manifestation a user may obtain about a system that passes the test suite we have set out. I was hoping we could give a basic minimum indication of the expected style of the version string for a git which *passes* our tests. But like you say, it doesn't form a real guarantee - caveat emptor still applies. ... Hence my suggestion of the basic test that a passing git would produce a consistent version string. I have been assuming that you are trying to avoid an exchange like this one we had in the past: http://thread.gmane.org/gmane.comp.version-control.git/216923/focus=217007 In a sense yes. As David noted, others do attempt to trust us via our current version string format. I thought it worthwhile (given my earlier 'mistake' in 216923/focus=216925) to suggest such a basic indication of our current string style. I also have been assuming that you are pushing to limit the possible versioning scheme, but I do not know what that extra limitation would achieve in the real world. By sticking to the pattern git gui happens to use, git gui may be able to guess that the next version of Git says it is verison 1.8.3. That is the _only_ thing your test buys. But having parsed the 1.8.3 substring out of it, git gui does not know anything about what 1.8.3 gives it. As far as it is concerned, it is a version whose git version output it has never seen (unless it has been kept up to date with the development of Git). You are focusssing on the wrong side of issue (from my viewpoint). If my earlier patch had gone in, it would have passsed our tests but not played nicely with the community tools. That would have been IMHO a regression, so from my viewpoint I believed it was worth having a test to avoid such a 'regression'. By matching against git version [1-9]+(\.[0-9]+)+, it is accepting that future versions may break assumptions it makes for some known versions (which is warranted) and all future versions (which is unwarranted) of Git. Maybe the version 2.0 of Git adds all changes in the directory d, including removals, when you say git add d, but it may have assumed that with Git version 1.5.0 or newer, saying git add d would result in added and modified inside that directory getting updated in the index, but paths removed from the working tree will stay in the index. If it was a gross incompatibility then (a) we are likley to be signalling it for a while, and (b) other tools would need updating as well, and they would hope that they could 'read' the version in a consistent style. We would also still have the choice of changing our existing string style, which would explicitly signal a change via the test fail. The only thing the scripts that read from the output of git version can reliably tell is if it is interacting with a version of Git it knows about. If it made any unwarranted assumption on the versions it hasn't seen, it has to be fixed in git gui _anyway_. Of course, we would not change the output of git version willy-nilly without good reason, but that is a different topic. Ah. I thought it was the [original] topic. I was calibrating the willy-nillyness ;-) So I do not know what you want to achieve in the real world with that extra limitation on the git version output format. Maybe you are proposing something else. I dunno. I was just using a slightly different philosophical approach. -- Philip -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Re: [PATCH] help.c: add a compatibility comment to cmd_version()
From: Junio C Hamano gits...@pobox.com
Sent: Tuesday, April 16, 2013 11:35 PM
Philip Oakley philipoak...@iee.org writes:
int cmd_version(int argc, const char **argv, const char *prefix)
{
+ /*
+ * The format of this string should be kept stable for
compatibility
+ * with external projects that rely on the output of git version.
This 'tantalizes without telling', the same complaint that is given
often for over-succinct commit messages.
How about
* E.g. git gui uses the extended regular expression ^git version
[1-9]+(\.[0-9]+)+.*
* to check for an acceptable version string.
The ERE is from git-gui.sh:L958.
Shouldn't the expected format of our known external project also be
indicated?
...
printf(git version %s\n, git_version_string);
It is fairly clear from the commented code that the only guarantee
they will be getting is that it begins with a string git version .
I read the code the opposite way. It says This is the code to be
changed if you (anyone doing tweaks) want a special version string.
git_version_string[] has anything of the builder's choice. I am not
sure if there anything more to indicate.
Really, if you run
$ git version
and you get Git Source Code Management Version 3.56 from its
output, it is likely that the version is very different from what
you know, and you should not assume any your assumption would hold.
Again I am reading this from the opposite side. There would be no
assumption of difference if it _passed_ the test scripts. Unfortunately
it wouldn't be friendly to other tools (like git gui). Hence my
suggestion of the basic test that a passing git would produce a
consistent version string. It still allows the supplier's suffixes to be
added, but not the prefixes. The test suite tests that git is 'good
enough for most usages and picks up regressions. No?
Obvious inconsistent special versions would fail in many other places.
Or mention such as git gui?
I do not see what it would buy us. It is not like it is OK as long
as we upadte Git gui at the same time.
Philip
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Re: [PATCH] help.c: add a compatibility comment to cmd_version()
Philip Oakley philipoak...@iee.org writes: How about * E.g. git gui uses the extended regular expression ^git version [1-9]+(\.[0-9]+)+.* * to check for an acceptable version string. The ERE is from git-gui.sh:L958. That is exactly the kind of guarantee we do _not_ want to give. ... Hence my suggestion of the basic test that a passing git would produce a consistent version string. I have been assuming that you are trying to avoid an exchange like this one we had in the past: http://thread.gmane.org/gmane.comp.version-control.git/216923/focus=217007 I also have been assuming that you are pushing to limit the possible versioning scheme, but I do not know what that extra limitation would achieve in the real world. By sticking to the pattern git gui happens to use, git gui may be able to guess that the next version of Git says it is verison 1.8.3. That is the _only_ thing your test buys. But having parsed the 1.8.3 substring out of it, git gui does not know anything about what 1.8.3 gives it. As far as it is concerned, it is a version whose git version output it has never seen (unless it has been kept up to date with the development of Git). By matching against git version [1-9]+(\.[0-9]+)+, it is accepting that future versions may break assumptions it makes for some known versions (which is warranted) and all future versions (which is unwarranted) of Git. Maybe the version 2.0 of Git adds all changes in the directory d, including removals, when you say git add d, but it may have assumed that with Git version 1.5.0 or newer, saying git add d would result in added and modified inside that directory getting updated in the index, but paths removed from the working tree will stay in the index. The only thing the scripts that read from the output of git version can reliably tell is if it is interacting with a version of Git it knows about. If it made any unwarranted assumption on the versions it hasn't seen, it has to be fixed in git gui _anyway_. Of course, we would not change the output of git version willy-nilly without good reason, but that is a different topic. So I do not know what you want to achieve in the real world with that extra limitation on the git version output format. Maybe you are proposing something else. I dunno. -- To unsubscribe from this list: send the line unsubscribe git in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
[PATCH] help.c: add a compatibility comment to cmd_version()
External projects have been known to parse the output of
git version. Help prevent future authors from changing
its format by adding a comment to its implementation.
Signed-off-by: David Aguilar dav...@gmail.com
---
help.c | 4
1 file changed, 4 insertions(+)
diff --git a/help.c b/help.c
index 1dfa0b0..02ba043 100644
--- a/help.c
+++ b/help.c
@@ -397,6 +397,10 @@ const char *help_unknown_cmd(const char *cmd)
int cmd_version(int argc, const char **argv, const char *prefix)
{
+ /*
+* The format of this string should be kept stable for compatibility
+* with external projects that rely on the output of git version.
+*/
printf(git version %s\n, git_version_string);
return 0;
}
--
1.8.2.1.652.ge104b5e
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Re: [PATCH] help.c: add a compatibility comment to cmd_version()
From: David Aguilar dav...@gmail.com
Sent: Tuesday, April 16, 2013 9:33 PM
External projects have been known to parse the output of
git version. Help prevent future authors from changing
its format by adding a comment to its implementation.
Signed-off-by: David Aguilar dav...@gmail.com
---
help.c | 4
1 file changed, 4 insertions(+)
diff --git a/help.c b/help.c
index 1dfa0b0..02ba043 100644
--- a/help.c
+++ b/help.c
@@ -397,6 +397,10 @@ const char *help_unknown_cmd(const char *cmd)
int cmd_version(int argc, const char **argv, const char *prefix)
{
+ /*
+ * The format of this string should be kept stable for compatibility
+ * with external projects that rely on the output of git version.
Shouldn't the expected format of our known external project also be
indicated?
Or mention such as git gui?
+ */
printf(git version %s\n, git_version_string);
return 0;
}
--
1.8.2.1.652.ge104b5e
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Re: [PATCH] help.c: add a compatibility comment to cmd_version()
Philip Oakley philipoak...@iee.org writes:
int cmd_version(int argc, const char **argv, const char *prefix)
{
+ /*
+ * The format of this string should be kept stable for compatibility
+ * with external projects that rely on the output of git version.
Shouldn't the expected format of our known external project also be
indicated?
...
printf(git version %s\n, git_version_string);
It is fairly clear from the commented code that the only guarantee
they will be getting is that it begins with a string git version .
git_version_string[] has anything of the builder's choice. I am not
sure if there anything more to indicate.
Really, if you run
$ git version
and you get Git Source Code Management Version 3.56 from its
output, it is likely that the version is very different from what
you know, and you should not assume any your assumption would hold.
Or mention such as git gui?
I do not see what it would buy us. It is not like it is OK as long
as we upadte Git gui at the same time.
--
To unsubscribe from this list: send the line unsubscribe git in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
