CODEWITHSUNDEEP
visual-studiomsbuild
Alan
Alan

Reputation: 2178

code reuse for file existence test in a Visual Studio vcxproj file

I have a vcxproj file that contains explicit Windows shell commands in the NMakeBuildCommandLine section:

<NMakeBuildCommandLine Condition="'$(Configuration)|$(Platform)'=='Debug|x64'">
move file1 file2
</NMakeBuildCommandLine>

I'm using MSBuild to execute the vcxproj, either directly or via a sln file. The problem is that when file1 does not exist, the output is very unhelpful and doesn't even list the file's name:

The system cannot find the file specified.

My naive solution is to replace move file1 file2 with:

if exist file1 (move file1 file2) else (echo file1 does not exist &amp;&amp; exit 1)

(Note that I need to write &amp;&amp; instead of &&.)

This works, but it's error-prone because I need to type file1 three times per line and make sure they all match. file1 is only one of many files that need to be moved. Furthermore, the series of commands is virtually identical across the various build configurations.

How can I avoid repeating myself both within a command line and across build configurations? I thought that the UserMacros property group might help me, but I couldn't figure out how to write such a macro via the IDE. (Right-clicking on the project in Visual Studio doesn't show a field for entering user macros.) Nor could I find any discussion of the syntax of this section on the Internet, so I didn't know how to write macros with a text editor (which I would actually prefer).

There may be yet a better way within a vcxproj file to identify files that need to exist, so I'm open to any alternatives.

Upvotes: 0

Views: 294

Answers (1)

stijn
stijn

Reputation: 35901

MsBuild has 'variables' like most other programming languages called properties. You declare one in a PropertyGroup element in the project file xml and then reuse it using the $(PropertyName) syntax. Example for your case:

<PropertyGroup>
  <Src>/path/to/my/src</Src>
  <Dst>/path/to/my/dst</Dst>
</PropertyGroup>

<NMakeBuildCommandLine>
if exist $(Src) (move $(Src) $(Dst)) else (echo $(Src) does not exist &amp;&amp; exit 1)
</NMakeBuildCommandLine>

If you want to use the IDE, which might get tedious if you have lots of values, you can indeed use so-called UserMacros but you have to declare those in a proprty sheet. Go to View->Property Manager, right-click on your project and select 'Add new Property Sheet'. Doubleclick on it, go to 'User Macros' and add key/value pairs there. If you save everything and look in the generated files you'll see the vcxproj now Imports the propertysheet, and the propertysheet itself has a PropertyGroup just like shown above - but editable thgough the IDE.

As an alternative which might be better (less duplication, easier to automate) in the long run you can use MsBuild code for checking file existence and moving files which has the benefit you only have to write the move command once as you can have MsBuild loop over items. Those are declared in an ItemGroup. Explaining everything here is a bit out of scope but an example should make things clear:

<Target Name="BatchMove">
  <ItemGroup>
    <SrcFiles Include="file1">
      <Dest>file2</Dest>
    </SrcFiles>
    <SrcFiles Include="file3">
      <Dest>file4</Dest>
    </SrcFiles>
  </ItemGroup>
  <Warning Text="Source file %(SrcFiles.Identity) does not exist" Condition="!Exists(%(SrcFiles.Identity))" />
  <Move SourceFiles="%(SrcFiles.Identity)" DestinationFiles="%(SrcFiles.Dest)" Condition="Exists(%(SrcFiles.Identity))" />
</Target>

This declares 2 source files file1/file3 and their respective destination files file2/file4. If the source does not exists (using standard MsBuild Exists check) a message is shown, else it is moved to the destination. Those % characters will make the line they occur in loop over each element of the SrcFiles collection. To add more files, just add to the ItemGroup. Last step is to get this target invoked from the nmake command line which is done simply by calling msbuild on the file itself and telling it to run the target:

<NMakeBuildCommandLine>
msbuild $(MSBuildThisFile) /t:BatchMove
</NMakeBuildCommandLine>

Upvotes: 1

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