Wrt. the proposed dupe: Since this here queston suggests the opposite of the linked question, I'd rather like to think it is not a dupe.
First, I did read What is the best practice for “Copy Local” and with project references? (also this) and I'll have to try this out anyway, but getting general feedback on this seems necessary as the docs on this stuff are horrible and I'm only on VS2010 and maybe they changed something in newer versions that'll be nice to know.
Second, I'm only interested in project references for this question as I've read that assemblies from the GAC are handled differently and the GAC is irrelevant for my problem.
Third, after reading the suggested dupe, but more so the nice answer here by #Albireo, it would also appear that it is important to differentiate file dependencies, where the dependency references a dll assembly file and project dependencies (i.e. what I'm asking about), where the dependency references a project and implicitly the output file of that project.
Anyway, here's the situation, somewhat peculiar I think, but still:
2 C# executable projects
n C# dll assembly projects
The 2 executables have different output directories as they will be deployed separately and that way they're also separate on the developer machine
The 2 executables have dependencies on some of the DLL assemblies (which may depend on each other)
There are three output directories:
/x1 for executable 1 project
/x2 for executable 2 project
/lib for all the dll assemblies
The DLL assemblies all have Copy Localset to false for their project references, as they all build to the same output directory.
The 2 executable projects have set Copy Local to true for all the DLL assembly project references they reference directly, so that the DLLs will be copied into /x1 /x2 respectively.
The question now is wrt. to DLLs that are not directly referenced by an executable project, but only transitively through a referenced assembly: Will assemblies, that are only referenced transitively through another assembly, be copied into the output folder of the executable, when "Copy Local" is set to true on the first assembly?
Example:
x1.csproj (e.g.Output = x1/one.exe)
Reference: dlA.csproj ( e.g. Output = lib/a.dll) with Copy Local = *true*
(no direct reference on b.dll)
dlA.csproj ( e.g. Output = lib/a.dll)
Reference: dlB.csproj ( e.g. Output = lib/b.dll) with Copy Local = **false**
(no direct reference on c.dll)
dlC.csproj ( e.g. Output = lib/c.dll)
(no further relevant references)
Thus, we have a logical dependency of one.exe -> a.dll -> b.dll -> c.dll, where only a.dll with obviously be copied to the output directory of one.exe. Will the other two dlls also be copied to the output directory? Is this documented somewhere?
And, yes, I tried it. And, yes, it seems to work, but I haven't poked it hard enough yet and anyway there maybe something more to it that I may have missed. (And also there's the question wrt. any official docs.)
it would also appear that it is important to differentiate file dependencies, where the dependency references a dll assembly file and project dependencies (i.e. what I'm asking about), where the dependency references a project and implicitly the output file of that project.
Not really, no.
MSBuild doesn't really care if the reference points to another project in the solution or to a DLL.
If ProjectA depends on ProjectB to build ProjectA ProjectB must be already built (and up-to-date), MSBuild will then pull its DLL (not its C# code) and link it to ProjectA.
Adding a project reference instead of a DLL is "syntactic sugar" for your convenience: this way MSBuild knows it must pick the output of the referenced project, whatever the output is.
Otherwise, you'll have to manually pre-build the dependency, find its DLL and link it to the project, repeating the process whenever you switch build configuration, move or rename things. Not really practical.
Will the other two dlls also be copied to the output directory?
If any kind of element from a dependency is used directly from the project where the assembly is referenced, that reference will be copied.
An example could be this solution layout:
MySolution
MySolution.ConsoleApplication
MySolution.FirstDependency
MySolution.SecondDependency
MySolution.ThirdDependency
MySolution.FourthDependency
With this dependency chain:
MySolution.ConsoleApplication
MySolution.FirstDependency
MySolution.SecondDependency
MySolution.ThirdDependency
MySolution.FourthDependency
If you build this solution you'll notice that in MySolution.ConsoleApplication output directory there will be the DLLs for MySolution.FirstDependency, MySolution.SecondDependency and MySolution.ThirdDependency but no DLL for MySolution.FourthDependency.
Why is it so? When MSBuild builds MySolution.SecondDependency it notices that there's a dependency declared to MySolution.FourthDependency, but since it can't find any usage of any kind of element from MySolution.FourthDependency in MySolution.SecondDependency code it decides to perform some "optimization" and omits MySolution.FourthDependency assembly from the output.
This same issue bit me in the past when I added through NuGet AutoMapper to a "deep dependency": adding AutoMapper adds two assembly references, AutoMapper and AutoMapper.Net4, where the second assembly is loaded by the first through reflection when it needs to perform certain kind of action on the new collection objects introduced by the .NET Framework 4. Since the second assembly is loaded through reflection MSBuild thinks it's unused and doesn't bother to copy it around.
So, yes, they will be copied as long as you're using them directly and not through reflection.
Is this documented somewhere?
This behavior seems to be a "feature" of MSBuild, I managed to find a blog post by some folks from Microsoft back when I experienced this issue, but I can't find it again at the moment.
It is very straight forward, doesn't have anything to do with Copy Local. MSBuild looks in the metadata of an assembly to see what the dependencies are for an assembly. So can you, run ildasm.exe on the assembly and double-click the Manifest. Be sure to try this to get insight. You'll see the .assembly directives. Inserted by the compiler when it built the assembly, only the referenced assemblies you actually used in your code will be listed.
If MSBuild can find such an assembly in the same directory then it will automatically copy it. If not then it will silently skip the copy.
From this, you can deduce the failure modes. It cannot copy unmanaged DLLs, they do not appear in the metadata. It cannot copy assemblies that you have an indirect dependency on through Assembly.Load/From(), they don't appear in the metadata either. It cannot copy assemblies that haven't been built yet, a build order problem. And it cannot copy assemblies whose Copy Local property you set to False. Which is normally only a valid choice if the assembly is present in the GAC, no copy required.
For such cases you need to help, XCOPY in a post-build event gets the job done.
Related
I am wondering if there are any heuristics for when to set copy-local=true for references?
If referenced types are only used internally can I set copy-local to true but if referenced types are exposed as parameters or return values I set copy-local to false and indicate that a specific version of the dependency should be referenced when my library should be used?
Can anyone clarify this for me?
Copy local is important for deployment scenarios and tools. As a general rule you should use CopyLocal=True if the reference is not contained within the GAC.
Copy Local essentially means I must manually deploy this DLL in order for my application to work. When it's false it essentially means "I depend on another component which must be installed separately or chained, the DLL will just be there already".
Copy local was implemented really to support local debugging. When you perpare your application for package and deployment you should build your projects to the same output folder and make sure you have all the references you need there.
CopyLocal is especially a pain when building large source trees. There was a related question about how to disable CopyLocal here on SO you can see it at How do I override CopyLocal (Private) setting for references in .NET from MSBUILD. As well as Best practices for large solutions in Visual Studio (2008).
I have written about how to deal with building large source trees in the article MSBuild: Best Practices For Creating Reliable Builds, Part 2.
So in short I would say disable CopyLocal when the file copying is causing your builds to take more time then you are willing to spend for every build.
It's really about the target environment. If copy local is false, you're saying that the assembly will already exist in the target environment (normally in the GAC). Setting it to true ensures it will appear in the output of your build, so makes it easier to deploy to the target environment.
Check out the following MSDN reference which explains CopyLocal behavior in detail.
Project References
Unfortunately there are some quirks and CopyLocal won't necessary work as expected for assembly references in secondary assemblies structured as shown below.
MainApp.exe
MyLibrary.dll
ThirdPartyLibrary.dll (if in the GAC CopyLocal won't copy to MainApp bin folder)
This makes xcopy deployments difficult if you don't plan on installing the third party assembly into the GAC on the target machine.
This option only affects build phase. It just copies the reference to local directory of the built assembly.
If another assembly (T) wants to use a method from the assembly you are building (A) which has return type or parameters from another referenced assembly (R), it (T) should be able to access that assembly (R). It might be able to do so without doing anything special if the referenced assembly (R) is installed in GAC. Otherwise, it needs a local copy of that.
Set CopyLocal=false will improve build time, but can cause different issues during deployment time.
My experience with setting CopyLocal=false wasn't successfull. See summary of pro and cons in my blog post "Do NOT Change "Copy Local” project references to false, unless understand subsequences."
Conservative way to set CopyLocal false is to check that the reference is found in the output path of the project. This should allow you to dodge some nasty runtime issues, while still reducing the amount of IO.
In the process I created CopyLocalFixer, which you can run for a folder. I tried this with one large build, but the results weren't that impressive to be honest. I guess it comes down to the folder structure of the project.
I have a project ProjectA in which I am keeping utility classes. I want to use this project in multiple solutions so I do not have to copy files, link files and update files every time I make changes in classes of Project.
But there seems to be a problem: if I am referencing ProjectA in ProjectB, the compiled application of ProjectB can not run unless there's a compiled application from ProjectA next to it. So if the output of ProjectB is ProjectB.exe, ProjectB.exe gives an error upon execution if ProjectA.exe is not next to it. Why is that? I just want to use namespaces from ProjectA in ProjectB, I do not need ProjectA to depend on a compiled version of ProjectB.
Can anyone tell me how to reference ProjectA in ProjectB without needing the output of ProjectA to run the output of ProjectB?
You probably need a shared dll.
You have created utility classes in project A out because they are shared all across project A (Application A?), now you have introduced project B (Application B) and as you state it needs to get hold of the code from projectA.dll/exe.
So create a new project in your solution (Ab.Shared.dll maybe:-)) and move your utiilty classes into it. You can now reference that dll from both project A and project B.
Update: Just read about your comment about sucking code out.
The shared dll is the most common way of sharing the code about, but there are other ways. Theoretically you can simply "include" the same *.cs files in both projects and share them that way (use the drop down on the Add existing item dialog and select Add as link) . However in practice it becomes more awkward maintaining this scenario so most people use a shared dll.
Namespaces are not restricted to one assembly - you can use the same namespace across several assemblies if you wish, and one assembly can contain as many namespaces as you like.
If you are referencing a class/type from another assembly, then that assembly must be present (or locatable) when you run the original assembly. If all you are doing is coding then a simple project reference in your solution will do the trick. If you don't have the source code to Project A then you will need it in its compiled form - without it the CLR cannot inspect it and know what it contains.
In that case add the ProjectA compiled dll in your bin folder and add the reference to that dll from your other project. Do not add reference to your ProjectA project.
When you add reference to the project using Visual studio, Add Reference -> Projects, then it requires the project to be compiled and it copies the dll/exe to the other project bin folder.
Open your csproj file in text editor and insert xml:
<Reference Include="AssemblyName.dll">
<HintPath>$(EnvironmentVariable)\bin\AssemblyName.dll</HintPath>
<Private>False</Private>
</Reference>
If I understand correctly, you have code in ProjectA.exe that you want to use in ProjectB.exe, but at run time, you'd like to run ProjectB.exe without requiring the user to have a copy of ProjectA.exe.
This is not possible. When you use a type from another assembly, that assembly is loaded at run time. The type is not copied from ProjectA to ProjectB.
It sounds to me like you should extract the common utility classes into ProjectUtility.dll, and then reference that from both your ProjectA.exe and ProjectB.exe applications.
EDIT: ILMERGE might be the way to go. See Linking statically in C# for more information.
I have a class library project, lets call it CoreLib.
CoreLib has two references to 3rd party DLL files 1.dll and 2.dll
Because I love reusability so much, I want to be able to use CoreLib in as many places as possible/needed.
So if I had a project called BigProjectA and another project called BigProjectB and they needed to leverage the functionality provided by CoreLib, all I would have to do is add a reference to CoreLib in those projects (BigProjectA and BigProjectB).
That is fine, except when I go to copy over my output folder (bin directory) to another person's computer, I can't guarantee that they have 1.dll and 2.dll on their machines.
For that, I just set Copy Local to True for 1.dll and 2.dll references in the CoreLib project.
When building the CoreLib project I can see 1.dll, 2.dll, and CoreLib.dll files. That is PERFECT!
But in the projects referencing CoreLib, only CoreLib.dll is copied over, not 1.dll and 2.dll.
Am I missing something? Copy Local set to True, but only copies for the CoreLib project. So even though they are in the same solution, and I'm adding CoreLib as a project reference to the other projects, I still dont see 1.dll and 2.dll copying out to the other bin/Debug, bin/Release folders of the other projects (BigProjectA and BigProjectB).
Is there an easy solution?
The easy solution is to either:
reference 1.DLL and 2.DLL in projects which have a binary reference to CoreData.DLL
Add CoreData as a project reference to BigProjectA and BigProjectB instead of as a binary reference
In the first scenario, CoreData's dependencies are not automatically output by the compiler. If the CoreData project is added to the solution, its dependencies will be output. Hence, to use CoreData as a binary reference, you must also reference its dependencies.
There is nothing wrong. In projects BigProjectA and BigProjectB you have a references to only CoreLib, so they "care" about coping only it, cause they have no any clue about it's dependencies. What you can do to resolve these kind of issue, is to add for example PostBuildVEent in your BigProject.. to copy also CoreLib dependencies.
Or add reference to CoreLib project, if you can.
Another solution, is to consider DI like a technique to avoid strong coupling of references. So, if in BigProjectA or B you don't care about functionality provided by 3rd party libraries in CoreLib, for you should be enough to just copy CoreLib.
Good answers guys....but I actually just ended up using ILMerge. Seemed safer/less annoying.
Thank you though
Has anyone experienced this or found a solution? I have tried the following:
Referencing the output dll directly without moving it
Uninstalling the output dll from the GAC
Neither option made a difference. Please note that the generated XML doc has the same name as the dll and is included with it.
Ah ha. I found the reason why this was occurring.
If you referencing your ILMerge project within Visual Studio (i.e. as Add Reference -> Project) then Intellisense will not use the generated XML doc.
To solve: In your post-build step copy your output files to a common directory (e.g. Reference Assemblies) and then link against the DLLs. You can still have the project in the solution, however you must setup the project dependencies so that it will build if you have made changes.
HTH,
I am using a 3rd party API which is defined in 2 DLLs. I have included those DLLs in my project and set references to them. So far so good.
However, these DLLs have at least one dependent DLL which cannot be found at runtime. I copied the missing DLL into the project and set the 'Copy to output' flag but without success.
What should I be doing here to tell the project where it should find the dependent DLL?
Clarification
I tried adding a reference to the missing DLL but as it wasn't recognised as a .Net component. In desperation, I added it directly to the output folder but without success.
Finally, I installed the API on the PC and it all worked. The installation sets the PATH variable and the DLL is found in the installation folder. But how to tell the project to look in one of its internal folders?
It sounds like you need to better understand the third-party library and how it uses its own dependencies. If the installation of the API solves the problem, but copying the files manually does not, then you're missing something. There's either a missing file, or some environment variable or registry entry that's required. Two things that will really help you in this is the depends tool (which is part of the C++ installation) and procmon, which will tell you all the registry keys and files that get used at runtime.
If you're lucky, it's just a file that you're missing. If that's all it is, you can use the "Build Events" section of the project to copy the needed files to the right location on a successful build. If not, you're going to have to solve this some other way - either by requiring the API be installed, or rolling your own installation project.
How are you deploying? Just flat files? If so, it should work as long as the file ends up in the project output directory. Does it?
If you are using another deployment, you will need to tell that engine to include it. This is different for each of msi/ClickOnce/etc.
You can either slowly add the downstream dependencies as references to your project. This is cumbersome, and somewhat fragile
Or your could use a tool like "Depends.exe" from microsoft to inspect your top level assemblies and get a reference list to the dependencies.