I'm trying to run down when a particular bug was created, but wading through the history is pretty time consuming. Is anyone familiar with a command line method to get a list of revisions where a line or range of lines changed?
svn and vault evangelists: I know, right....but you can't always pick the environment....
I don't think SourceSafe has an easy way to do this.. but I haven't used SourceSafe since version 2005. One method you could try is using a divide and conquer search.
First, pick a date in way in the future, if the bug is there, double the length, until you find a version without the bug.
You just need two known points to work with, one when you know the bug is there, and one where you know the bug isn't there, cut those two in half and check the version in the middle. if the bug is there cut the top half in half, if its not cut the bottom half into half.
This will be way more effective then looking in every file version.
I don't remember if SourceSafe has a version number for each file, if not you could just use the scrollbar as your guide for where the halfway point is.
Related
I'm working on a new weave-based data structure for storing version control history. This will undoubtedly cause some religious wars about whether it's The Right Way Of Doing Things when it comes out, but that isn't my question right now.
My question has to do with what output blame should give. When a line of code has been added, removed, and merged into itself a number of times, it isn't always clear what revision should get blame for it. Notably this means that when a section of code is deleted, all records of it having been there is gone, and there is no blame for the removal. Everyone I've gone over this issue with has said that trying to do better simply isn't worth it. Sometimes people put in the hack that the line after the section which got deleted has its blame changed from whatever it actually was to the revision when the section got deleted. Presumably if the section is at the end then the last line get its blame changed, and if the file winds up empty then the blame really does disappear into the aether, because there's literally nowhere left to put blame information. For various technical reasons I won't be using this hack, but assume that continuing but with this completely undocumented but de facto standard practice will be uncontroversial (but feel free to flame me and get it out of your system).
Moving on to my actual question. Usually in blame for each line you look at the complete history of where it was added and removed in the history and using three-way merge (or, in the case of criss-cross merges, random bullshit) and based on the relationships between those you determine whether the line should have been there based on its history, and if it shouldn't but is then you mark it as new with the current revision. In the case where a line occurs in multiple ancestors with different blames then it picks which one to inherit arbitrarily. Again, I assume that continuing with this completely undocumented but de facto standard practice will be uncontroversial.
Where my new system diverges is that rather than doing a complicated calculation of whether a given line should be in the current revision based on a complex calculation of the whole history, it simply looks at the immediate ancestors, and if the line is in any of them it picks an arbitrary one to inherit the blame from. I'm making this change for largely technical reasons (and it's entirely possible that other blame implementations do the same thing, for similar technical reasons and a lack of caring) but after thinking about it a bit part of me actually prefers the new behavior as being more intuitive and predictable than the old one. What does everybody think?
I actually wrote a one of the blame implementations out there (Subversion's current one I believe, unless someone replaced it in the past year or two). I helped with some others as well.
At least most implementations of blame don't do what you describe:
Usually in blame for each line you look at the complete history of where it was added and removed in the history and using three way merge (or, in the case of criss-cross merges, random bullshit) and based on the relationships between those you determine whether the line should have been there based on its history, and if it shouldn't but is then you mark it as new with the current revision. In the case where a line occurs in multiple ancestors with different blames then it picks which one to inherit arbitrarily. Again, I assume that continuing with this completely undocumented but de facto standard practice will be uncontroversial.
Actually, most blames are significantly less complex than this and don't bother trying to use the relationships at all, but they just walk parents in some arbitrary order, using simple delta structures (usually the same internal structure whatever diff algorithm they have uses before it turns it into textual output) to see if the chunk changed, and if so, blame it, and mark that line as done.
For example, Mercurial just does an iterative depth first search until all lines are blamed. It doesn't try to take into account whether the relationships make it unlikely it blamed the right one.
Git does do something a bit more complicated, but still, not quite like you describe.
Subversion does what Mercurial does, but the history graph is very simple, so it's even easier.
In turn, what you are suggesting is, in fact, what all of them really do:
Pick an arbitrary ancestor and follow that path down the rabbit hole until it's done, and if it doesn't cause you to have blamed all the lines, arbitrarily pick the next ancestor, continue until all blame is assigned.
On a personal level, I prefer your simplified option.
Reason: Blame isn't used very much anyway.
So I don't see a point in wasting a lot of time doing a comprehensive implementation of it.
It's true. Blame has largely turned out to be one of those "pot of gold at the end of the rainbow" features. It looked really cool from those of us standing on the ground, dreaming about a day when we could just click on a file and see who wrote which lines of code. But now that it's widely implemented, most of us have come to realize that it actually isn't very helpful. Check the activity on the blame tag here on Stack Overflow. It is underwhemingly desolate.
I have run across dozens of "blame-worthy" scenarios in recent months alone, and in most cases I have attempted to use blame first, and found it either cumbersome or utterly unhelpful. Instead, I found the information I needed by doing a simple filtered changelog on the file in question. In some cases, I could have found the information using Blame as well, had I been persistent, but it would have taken much longer.
The main problem is code formatting changes. The first-tier blame for almost everything was listed as... me! Why? Because I'm the one responsible for fixing newlines and tabs, re-sorting function order, splitting functions into separate utility modules, fixing comment typos, and improving or simplifying code flow. And if it wasn't me, someone else had done a whitespace or block-move somewhere along-the-way as well. In order to get a meaningful blame on anything dating back to a time before I can already remember without the help of blame, I had to roll back revisions and re-blame. And re-blame again. And again.
So in order for a blame to actually be a useful time saver for more than the most lucky of situations, the blame has to be able to heuristicly make its way past newline, whitespace, and ideally block copy/move changes. That sounds like a very tall order, especially when scouring the changelog for a single file, most of the time, it won't yield many diffs anyway and you can just sift through by hand fairly quickly. (The notable exception being, perhaps, badly engineered source trees where 90% of the code is stuffed in one or two ginormous files... but who these days in a collaborative coding environment does much of that anymore?).
Conclusion: Give it a bare-bones implementation of blame, because some people like to see "it can blame!" on the features list. And then move on to things that matter. Enjoy!
The line-merge algorithm is stupider than the developer. If they disagree, that just indicates that the merger is wrong rather than indicating a decision point. So, the simplified logic should actually be more correct.
I have two data files. They're both 5000 lines long, and each row is ~10000 characters wide. They are nearly identical, except a few characters on some lines are different. Is there any tool that will jump both vertically and horizontally to the disagreements for both sides, so I can see what's different?
I'm using OSX, but I could use Linux or windows if it was absolutely necessary. I've tried:
FileMerge
KDiff3
DiffMerge
command line diff
Now trying to install meld
vimdiff, or even better its graphical twin gvimdiff, would work if there is at most two edits per line. It highlights the part between the first and last changed character on a line. It also collapses the parts of the files which are identical.
These are part of Vim; I have no idea whether the MacOS versions contain (g)vimdiff.
Note that in my experience Vim sometimes becomes slow with long lines, so that might hurt you for this specific use case.
Araxis Merge may do what you're after (it does character-diffs within lines), and there's an OSX version. It's not cheap, and I've never tried it on 10,000 character wide lines, though.
I have a lot of HTML files (10,000's and GBs worth) scraped from a server and I want to check to make sure the server produces the same results after some modifications but ignore kinds of differences that don't matter, e.g. whitespace, missing newlines, timestamps, small changes in some kinds of number, etc.
Does anyone know of a tool for doing this? I'd really rather not do more filtering than I have to.
(Oh and it needs to run under linux)
You might consider using a clone detector such as our CloneDR. This tool parses large sets of computer program (HTML is special case) files, builds abstract syntax trees representing the essential structure of each files, and compares programs for similarity.
Because it is comparing essential program structure, it ignores inessential differences such as comments and whitespace, and deterimines that two code segments are either identical or one can be obtained from the other by substituting other blocks of code. The latter allows the recognition of code that has been modified in various ways. You can see samples of clone detection runs on a variety of computer languages at the web site.
In your case, what you would be looking for are files in system A which are essentially clones (exact or near misses) of files in system B. As a general rule, if a file a is a variant of file b (e.g., with a few changes) the CloneDr will report it as a clone and show the exact differences.
At the scale of 20,000 files, I can see why you want a tool, and I can see why you want near-miss matches rather than exact matches.
Doesn't run under Linux, but I assume your problem is hard to enough to solve so that isn't what you are optimizing.
I use winmerge alot in windows and from what i can see some people enjoy meld in linux, so perhaps that could do the trick for you
http://meld.sourceforge.net/
Other examples i saw from a quick googling was Kompare,xxdiff.sourceforge.net, and kdiff3.sourceforge.net
(could only post 1 link so wrote the adresses to xxdiff and kdiff3 as text)
Beyond Compare is purchased software that is actually worth the money (I never thought I'd hear myself typing that!). It is GUI based but handles thousands of files very well. It will allow you to specify unimportant changes with regular expressions as well as whitespace (beginning, middle and end of line). The feature set is very extensive, check out a trial download.
I do not work for this company, I just use Beyond Compare every day at work and enjoy it every time!
I'm a TDDer and often have a need to refactor out common or similar code. Similar code is not always a result of copy and paste.
I'm not looking for tools to identify the regions or suspected duplications, there are a number of tools to do that. And if the code is exactly the same there is no big problem, Eclipse can almost always do that by itself.
I am looking for tools to visualize differences of sections of code that are radically different, but my human eye can see the structural similarities, and could possibly be made even more similar, so that the common code eventually could be factored out.
It would be very handy if there was a possibility to mark two regions and get Eclipse (or some other tool) to mark the differences. With this information it would be much simpler to iteratively move the regions closer until they are the same and then activate the Extract Method refactoring.
It can be done in Emacs of course, but I'd like to have this readily available from Eclipse. Any pointers?
Seems there was somewhat usable answers in this question, a question articulating the same need. But, again those answers focus on finding duplications, not vizualising it.
Two suggestions that works are KDiff3 and Diffuse. Both allow you to open up the same file twice or paste different sections in the panes. There seems to be no way to use them from Eclipse though.
I don not know of a way to mark regions and diff them in eclipse, but you can diff two files. In that way you might get what you are looking for by copying out the parts you want to diff in two paste files, at least 90%?
Select the two files you want to diff in the project tree and right-click -> select compare with -> each other.
cheers,
Jørgen
What source control products have a "diff" facility that ignores white space, braces, etc., in calculating the difference between checked-in versions? I seem to remember that Clearcase's diff did this but Visual SourceSafe (or at least the version I used) did not.
The reason I ask is probably pretty typical. Four perfectly reasonable developers on a team have four entirely different ways of formatting their code. Upon checking out the code last changed by someone else, each will immediately run some kind of program or editor macro to format things the way they like. They make actual code changes. They check-in their changes. They go on vacation. Two days later that program, which had been running fine for two years, blows up. The developer assigned to the bug does a diff between versions and finds 204 differences, only 3 of which are of any significance, because the diff algorithm is lame.
Yes, you can have coding standards. Most everyone finds them dreadful. A solution where everyone can have their cake and eat it too seems far more preferable.
=========
EDIT: Thanks to everyone for some great suggestions.
What I take away from this is:
(1) A source control system with plug-in type diffs is preferable.
(2) Find a diff with suitable options.
(3) Use a good source formatting program and settle on a check-in standard.
Sounds like a plan. Thanks again.
Git does have these options:
--ignore-space-at-eol
Ignore changes in whitespace at EOL.
-b, --ignore-space-change
Ignore changes in amount of whitespace. This ignores whitespace at line end, and considers all other sequences of one or more
whitespace characters to be equivalent.
-w, --ignore-all-space
Ignore whitespace when comparing lines. This ignores differences even if one line has whitespace where the other line has
none.
I am not sure if brace changes can be ignored using Git's diff.
If it is C/C++ code, you can define Astyle rules and then convert the source code's brace style to the one that you want, using Astyle. A git diff will then produce sane output.
Choose one (dreadful) coding standard, write it down in some official coding standards document, and get on with your life, messing with whitespace is not productive work.
And remember you are a professional developer, it's your job to get the project done, changing anything in the code because of a personal style preference hurts the project - it wont only make diff-ing more difficult, it can also introduce hard to find problems if your source formatter or compiler has bugs (and your fancy diff tool won't save you when two co-worker start fighting over casing).
And if someone just doesn't agree to work with the selected style just remind him (or her) that he is programming as a profession not as an hobby, see http://www.ericsink.com/entries/No_Great_Hackers.html
Maybe you should choose one format and run some indentation tool before checking in so that each person can check out, reformat to his/her own preferences, do the changes, reformat back to the official standard and then check in?
A couple of extra steps but they already use indentation tools when working. Maybe it can be a triggered check-in script?
Edit: this would perhaps also solve the brace problem.
(I haven't tried this solution myself, hence the "perhapes" and "maybes", but I have been in projects with the same problems, and it is a pain to try to go through diffs with hundreds of irrelevant changes that are not limited to whitespace, but includes the formatting itself.)
As explained in Is it possible for git-merge to ignore line-ending differences?, it is more a matter to associate the right diff tool to your favorite VCS, rather than to rely on the right VCS option (even if Git does have some options regarding whitespace, like the one mentioned in Alan's answer, it will always be not as complete as one would like).
DiffMerge is the more complete on those "ignore" options, as it can not only ignore spaces but also other "variations" based on the programming language used in a given file.
Subversion apparently supports this, either natively in the latest versions, or by using an alternate diff like Gnu Diff.
Beyond Compare does this (and much much more) and you can integrate it either in Subversion or Sourcesafe as an external diff tool.