VS2010 custom build tool for generating .h file - c++

Question

I'm trying to integrate a custom build tool in VS2010 that generates a .h-file from a source file. I've created a .xml, .targets and .props for the step. The XML is mostly copy-pasted from the MASM-file and ends with:
<ItemType Name="FOO" DisplayName="Foo compiler" />
<FileExtension Name="*.foo" ContentType="FOO" />
<ContentType Name="FOO" DisplayName="Foo compiler" ItemType="FOO" />
This maps all my .foo files to the Foo compiler that's defined in the .props:
<?xml version="1.0" encoding="utf-8"?>
<Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
<ItemGroup>
<PropertyPageSchema Include="$(MSBuildThisFileDirectory)$(MSBuildThisFileName).xml" />
<AvailableItemName Include="FOO">
<Targets>FooCompile</Targets>
</AvailableItemName>
</ItemGroup>
<UsingTask TaskName="FOO" TaskFactory="XamlTaskFactory" AssemblyName="Microsoft.Build.Tasks.v4.0">
<Task>$(MSBuildThisFileDirectory)$(MSBuildThisFileName).xml</Task>
</UsingTask>
<Target Name="FooCompile" BeforeTargets="$(FOOBeforeTargets)" AfterTargets="$(FOOAfterTargets)" Condition="'#(FOO)' != ''" Outputs="%(FOO.Outputs)" Inputs="%(FOO.Identity);%(FOO.AdditionalDependencies);$(MSBuildProjectFile)" DependsOnTargets="_SelectedFiles">
<Message Importance="High" Text="#(FOO)" />
<FOO Condition="'#(FOO)' != '' and '%(FOO.ExcludedFromBuild)' != 'true'"
CommandLineTemplate="%(FOO.CommandLineTemplate)"
OutputFileName="%(FOO.OutputFileName)"
Inputs="%(FOO.Identity)" />
</Target>
</Project>
When I compile my project it successfully identifies and compiles my foo files:
1>FooCompile:
1> apa.foo
1>FooCompile:
1> banan.foo
1>ClCompile:
1> test.cpp
1> main.cpp
My question is why does it print "FooCompile:" once for each file while the ClCompile doesn't? Is there any way to change this?
If I change a cpp file and build, I'll also get this output once for each file, which I want to avoid:
1>FooCompile:
1>Skipping target "FooCompile" because all output files are up-to-date with respect to the input files.
1>FooCompile:
1>Skipping target "FooCompile" because all output files are up-to-date with respect to the input files.

Answer 1

The FooCompile target is using "target batching" which causes the target to iterate once for each item in the array specified for the Outputs attribute, %(Foo). The ClCompile target on the other hand operates using the entire item array #(ClCompile).
You can alter the verbosity of the logger to avoid the messages, specify /v:minimal, but of course you may be filtering out other information as well.