I've seen this message pop up a couple times when running cabal v1-install with a suggestion to use --force-reinstalls to install anyway. As I don't know that much about cabal, I'm not sure why a package would break due to a reinstall. Could someone please fill me in on the backstory behind this message?
Note for future readers: this discussion is about historical matters. For practical purposes, you can safely ignore all of that if you are using Cabal 3.
The problem had to do with transitive dependencies. For instance, suppose we had the following three packages installed at specific versions:
A-1.0;
B-1.0, which depends on A; and
C-1.0, which depends on B, but not explicitly on A.
Then, we would install A-1.1, which seemingly would work fine:
A-1.1 would be installed, but the older A-1.0 version would be kept around, solely for the sake of other packages built using it;
B-1.0 would keep using A-1.0; and
C-1.0 would keep using B-1.0.
However, there would be trouble if we, for whatever reason, attempted to reinstall B-1.0 (as opposed to, say, update to B-1.1):
A-1.1 and A-1.0 would still be available for other packages needing them;
B-1.0, however, would be rebuilt against A-1.1, there being no way of keeping around a second installation of the same version of B; and
C-1.0, which was built against the replaced B-1.0 (which depended on A-1.0), would now be broken.
v1-install provided a safeguard against this kind of dangerous reinstall. Using --force-reinstalls would disable that safeguard.
For a detailed explanation of the surrounding issues, see Albert Y. C. Lai's Storage and Identification of Cabalized Packages (in particular, the example I used here is essentially a summary of its Corollary: The Pigeon Drop Con section).
While Cabal 1, in its later versions, was able to, in the scenario above, detect that the reinstall changed B even though the version number remained the same (which is what made the safeguard possible), it couldn't keep around the two variants of B-1.0 simultaneously. Cabal 3, on the other hand, is able to do that, which eliminates the problem.
I am using alternative version numbering approach for my projects. I have encountered strange behavior by cabal and stack that does not allow me to fully enjoy benefits of this approach. Both cabal and stack enforce version to be of format Int.Int.Int, which does not cover the case of another version format I use for branches (0.x.x, 1.x.x, 1.0.x, etc).
If I have line version: 0.x.x in my .cabal file, I am getting Parse of field 'version' failed. error when running cabal build or Unable to parse cabal file {PROJECT_NAME}.cabal: NoParse "version" 5 when running stack init.
Is there a way to disable version parsing on cabal and stack commands? Is there a flag for it? Or do I have to request this kind of change (adding flags, disabling version parsing) from the developers of cabal and stack?
Why is there any parsing at all? How does it help with building a package? Does cabal or stack automatically increment build numbers on some event? If yes, where could I read more about this? How could I influence the way version numbering incrementation gets implemented in cabal and stack? I want developers of haskell packages take into account the possibility of alternative version numbering approaches.
PS. For all interested folks, I want to quickly summarize the idea behind "weird" version numbers, such as 0.x.x, 1.x.x, 1.0.x. I use the version numbers with x's to describe streamlines of development that allow code changes while such version numbers as 1.0.0, 1.1.0, 2.35.46 are used to describe frozen states of development (to be precise, they are used for released versions of software). Note that such version numbers as 0.x.0, 1.x.15, 2.x.23 are also possible (used for snapshots/builds of software) and they mean that codebase has been inherited from branches with version numbers 0.x.x, 1.x.x and 2.x.x correspondingly.
Why do I need such version numbers as 0.x.x, 1.x.x and 2.x.x at all? In brief, different number of x's mean branches of different types. For example, version number pattern N.x.x is used for support branches, while pattern N.M.x is used for release branches. Idea behind support branches is that they get created due to incompatibility of the corresponding codebases. Release branches get created due to feature freeze in corresponding codebase. For example, branches 1.0.x, 1.1.x, 1.2.x, ... get created as a result of feature freezes (or releases) in branch 1.x.x.
I know this is all confusing, but I worked hard to establish this version numbering approach and I continue working on awareness about the inconsistencies of version numbering through my presentations and other projects. This all makes sense once you think more about the pitfalls of semver approach (you can find detailed slideshare presentation on the matter following the link). But I do not want to defend it for now. For the time being, I just want cabal and stack to stop enforcing their, as I perceive them, unjustified rules to my project. Hope you can help me with that.
You can't. The version will be parsed to Version, which is:
data Version = PV0 {-# UNPACK #-} !Word64
| PV1 !Int [Int]
Stack uses Cabal as a library but has its own Version type:
newtype Version =
Version {unVersion :: Vector Word}
deriving (Eq,Ord,Typeable,Data,Generic,Store,NFData)
Neither cabal nor stack have a way to customize the parsing. You have to write your own variant of those programs if you want to use another version type. But then again, you're not winning anything at that point: neither Hackage nor Stackage will recognize your package's version.
So the 1.x.x isn't possible at the moment. You could exchange x with 99999999 or something similar to mitigate the problem. That being said, it's not clear what cabal install should then install. The 99999999 version? Or the latest stable variant?
If you can express the semantics, a discussion on the mailing list as well as a feature request might change the behaviour in the (far away) future, but for now, you either have to patch the programs yourself or use another numbering scheme.
Is there a way to disable version parsing on cabal and stack commands? Is there a flag for it?
No.
Or do I have to request this kind of change (adding flags, disabling version parsing) from the developers of cabal and stack?
You can of course ask, but there are so many outstanding issues that you are unlikely to get any traction. You will have to be very convincing -- convincing enough to overturn more than 20 years of experience that says the current versioning scheme is basically workable. Realistically, if you want this to happen you'll probably have to maintain a fork of these tools yourself, and provide an alternative place to host packages using this scheme.
Why is there any parsing at all? How does it help with building a package?
Packages specify dependencies, and for each dependency, specify what version ranges they work with. The build tools then use a constraint solver to choose a coherent set of package/version pairs to satisfy all the (transitive) dependencies. To do this, they must at a minimum be able to check whether a given version is in a given range -- which requires parsing the version number at least a little bit.
Does cabal or stack automatically increment build numbers on some event? If yes, where could I read more about this?
There is nothing automatic. But you should take a look at the Package Version Policy, which serves as a social contract between package maintainers. It lets one package maintainer say, "I am using bytestring version 0.10.0.1 and it seems to work. I'm being careful about qualifying all my bytestring imports; therefore I can specify a range like >=0.10 && <0.11 and be sure that things will just work, while giving the bytestring maintainer the ability to push security and efficiency updates to my users." without having to pore through the full documentation of bytestring and hope its maintainer had written about what his version numbers mean.
How could I influence the way version numbering incrementation gets implemented in cabal and stack?
As with your previous question about changing the way the community does things, I think modifications to the Package Versioning Policy are going to be quite difficult, especially changes as radical as you seem to be proposing here. The more radical the change, the more carefully motivated it will have to be to gain traction.
I honestly don't know what a reasonable place to take such motivation and discussion would be; perhaps the haskell-cafe mailing list or similar.
For non trivial projects is commonly split it in several packages (in particular, I work usually with Visual Studio C# solutions containing 1-10 projects).
My current Haskell workflow is perform cabal clean && cabal configure && cabal install --force-reinstall for each time I modify some package that is used in another one.
That's works fine but I wish work with several Haskell projects as if only one be (ideally if A and B projects was modified then using ghci A detect changes on B).
The proposed solution (if possible) should work fine too if certain package A (in development) is shared in several "workspaces".
I looked for, but the unique related response (Haskell Cafe, Working with multiple projects 2009) suggest my current workflow as solution.
Any tutorial explaining it (workspaces, shared "in development" packages, ...) will be welcome!
Thanks a lot!!! :)
(I'm working with ghc)
So, basically you can use cabal-dev to make a local sandbox of the packages you want to use for a given project. This is will stop different projects that may have conflicting package requirements from mucking every thing up.
Here is a good post on reddit explaining the basics.
http://www.reddit.com/r/haskell/comments/f3ykj/psa_use_cabaldev_to_solve_dependency_problems/
In Visual Studio 6 the project settings dialog box is not resizable. Is there a reason for it to be so?
I know this is a long shot, but any trick to "fix" this problem?
I know this is a long shot, but any trick to "fix" this problem?
The "trick" is to edit the resources for the executable manually and make the dialog boxes resizable.
But that doesn't actually solve the problem, or someone at Microsoft would surely have done that for one of the many intervening versions of Visual Studio between 6 and 10. In fact, this very thing has been repeatedly suggested on Microsoft Connect and UserVoice (among other places) as a substantial usability problem, and there seems to be general agreement about that fact.
The real problem is that you have to write code to get the controls on the dialog box to automatically resize when their container (the dialog) is resized. Since that's non-trivial, it hasn't been done yet for any of the new releases of VS. And there's no way to go back and do it on one of the old versions, since editing code in a compiled executable is something I wouldn't recommend to anyone.
It still might happen in a future version of VS, which should be a compelling reason to upgrade for everyone, much less people that are still using VC++ 6, a product released nearly 15 years ago.
Keep your fingers crossed.
As far as adding it to VC++ 6 now, it's simply not possible. Your best hope would be a third-party extension that replaces the dialog with a resizable one. It won't be exactly equivalent to the built-in dialog, though, and it'll be very hard to find such add-on utilities now, given their age. You'd probably need to visit a museum.
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I distribute software online, and always wonder if there is a proper way to better define version numbers.
Let's assume A.B.C.D in the answers. When do you increase each of the components?
Do you use any other version number tricks such as D mod 2 == 1 means it is an in house release only?
Do you have beta releases with their own version numbers, or do you have beta releases per version number?
I'm starting to like the Year.Release[.Build] convention that some apps (e.g. Perforce) use. Basically it just says the year in which you release, and the sequence within that year. So 2008.1 would be the first version, and if you released another a months or three later, it would go to 2008.2.
The advantage of this scheme is there is no implied "magnitude" of release, where you get into arguments about whether a feature is major enough to warrant a major version increment or not.
An optional extra is to tag on the build number, but that tends to be for internal purposes only (e.g. added to the EXE/DLL so you can inspect the file and ensure the right build is there).
In my opinion, almost any release number scheme can be made to work more or less sanely. The system I work on uses version numbers such as 11.50.UC3, where the U indicates 32-bit Unix, and the C3 is a minor revision (fix pack) number; other letters are used for other platform types. (I'd not recommend this scheme, but it works.)
There are a few golden rules which have not so far been stated, but which are implicit in what people have discussed.
Do not release the same version twice - once version 1.0.0 is released to anyone, it can never be re-released.
Release numbers should increase monotonically. That is, the code in version 1.0.1 or 1.1.0 or 2.0.0 should always be later than version 1.0.0, 1.0.9, or 1.4.3 (respectively).
Now, in practice, people do have to release fixes for older versions while newer versions are available -- see GCC, for example:
GCC 3.4.6 was released after 4.0.0, 4.1.0 (and AFAICR 4.2.0), but it continues the functionality of GCC 3.4.x rather than adding the extra features added to GCC 4.x.
So, you have to build your version numbering scheme carefully.
One other point which I firmly believe in:
The release version number is unrelated to the CM (VCS) system version numbering, except for trivial programs. Any serious piece of software with more than one main source file will have a version number unrelated to the version of any single file.
With SVN, you could use the SVN version number - but probably wouldn't as it changes too unpredictably.
For the stuff I work with, the version number is a purely political decision.
Incidentally, I know of software that went through releases from version 1.00 through 9.53, but that then changed to 2.80. That was a gross mistake - dictated by marketing. Granted, version 4.x of the software is/was obsolete, so it didn't immediately make for confusion, but version 5.x of the software is still in use and sold, and the revisions have already reached 3.50. I'm very worried about what my code that has to work with both the 5.x (old style) and 5.x (new style) is going to do when the inevitable conflict occurs. I guess I have to hope that they will dilly-dally on changing to 5.x until the old 5.x really is dead -- but I'm not optimistic. I also use an artificial version number, such as 9.60, to represent the 3.50 code, so that I can do sane if VERSION > 900 testing, rather than having to do: if (VERSION >= 900 || (VERSION >= 280 && VERSION < 400), where I represent version 9.00 by 900. And then there's the significant change introduced in version 3.00.xC3 -- my scheme fails to detect changes at the minor release level...grumble...grumble...
NB: Eric Raymond provides Software Release Practice HOWTO including the (linked) section on naming (numbering) releases.
I usually use D as a build counter (automatic increment by compiler)
I increment C every time a build is released to "public" (not every build is released)
A and B are used as major/minor version number and changed manually.
I think there are two ways to answer this question, and they are not entirely complimentary.
Technical: Increment versions based on technical tasks. Example: D is build number, C is Iteration, B is a minor release, A is a major release. Defining minor and major releases is really subjective, but could be related things like changes to underlying architecture.
Marketing: Increment versions based on how many "new" or "useful" features are being provided to your customers. You may also tie the version numbers to an update policy...Changes to A require the user to purchase an upgrade license, whereas other changes do not.
The bottom line, I think, is finding a model that works for you and your customers. I've seen some cases where even versions are public releases, and odd versions are considered beta, or dev releases. I've seen some products which ignore C and D all together.
Then there is the example from Micrsoft, where the only rational explanation to the version numbers for the .Net Framework is that Marketing was involved.
Our policy:
A - Significant (> 25%) changes or
additions in functionality or
interface.
B - small changes or
additions in functionality or
interface.
C - minor changes that
break the interface.
D - fixes to a
build that do not change the
interface.
People tend to want to make this much harder than it really needs to be. If your product has only a single long-lived branch, just name successive versions by their build number. If you've got some kind of "minor bug fixes are free, but you have to pay for major new versions", then use 1.0, 1.1 ... 1.n, 2.0, 2.1... etc.
If you can't immediately figure out what the A,B,C, and D in your example are, then you obviously don't need them.
The only use I have ever made of the version number was so that a customer could tell me they're using version 2.5.1.0 or whatever.
My only rule is designed to minimize mistakes in reporting that number: all four numbers have to be 1 digit only.
1.1.2.3
is ok, but
1.0.1.23
is not. Customers are likely to report both numbers (verbally, at least) as "one-one-two-three".
Auto-incrementing build numbers often results in version numbers like
1.0.1.12537
which doesn't really help, either.
A good and non-technical scheme just uses the build date in this format:
YYYY.MM.DD.BuildNumber
Where BuildNumber is either a continuous number (changelist) or just starts over at 1 each day.
Examples: 2008.03.24.1 or 2008.03.24.14503
This is mainly for internal releases, public releases would see the version printed as 2008.03 if you don't release more often than once a month. Maintenance releases get flagged as 2008.03a 2008.03b and so on. They should rarely go past "c" but if it does it's a good indicator you need better QA and/or testing procedures.
Version fields that are commonly seen by the user should be printed in a friendly "March 2008" format, reserve the more technical info in the About dialog or log files.
Biggest disadvantage: just compiling the same code on another day might change the version number. But you can avoid this by using the version control changelist as last number and checking against that to determine if the date needs to be changed as well.
In the github world, it has become popular to follow Tom Preston-Werner's "semver" spec for version numbers.
From http://semver.org/ :
Given a version number MAJOR.MINOR.PATCH, increment the:
MAJOR version when you make incompatible API changes, MINOR version
when you add functionality in a backwards-compatible manner, and PATCH
version when you make backwards-compatible bug fixes. Additional
labels for pre-release and build metadata are available as extensions
to the MAJOR.MINOR.PATCH format.
I use V.R.M e.g. 2.5.1
V (version) changes are a major rewrite
R (revision) changes are significant new features or bug fixes
M (modification) changes are minor bux fixes (typos, etc)
I sometimes use an SVN commit number on the end too.
Its all really subjective at the end of the day and simply up to yourself/your team.
Just take a look at all the answers already - all very different.
Personally I use Major.Minor.*.* - Where Visual Studio fills in the revison/build number automatically. This is used where I work too.
I like Year.Month.Day. So, v2009.6.8 would be the "version" of this post. It is impossible to duplicate (reasonably) and it very clear when something is a newer release. You could also drop the decimals and make it v20090608.
In the case of a library, the version number tells you about the level of compatibility between two releases, and thus how difficult an upgrade will be.
A bug fix release needs to preserve binary, source, and serialization compatibility.
Minor releases mean different things to different projects, but usually they don't need to preserve source compatibility.
Major version numbers can break all three forms.
I wrote more about the rationale here.
For in-house development, we use the following format.
[Program #] . [Year] . [Month] . [Release # of this app within the month]
For example, if I'm releasing application # 15 today, and it's the third update this month, then my version # will be
15.2008.9.3
It's totally non-standard, but it is useful for us.
For the past six major versions, we've used M.0.m.b where M is the major version, m is the minor version, and b is the build number. So released versions included 6.0.2, 7.0.1, ..., up to 11.0.0. Don't ask why the second number is always 0; I've asked a number of times and nobody really knows. We haven't had a non-zero there since 5.5 was released in 1996.