Option to support configure the Item likes property

[WeihanLi]

For property, we could use -property:<name>=<value>, is there any plan to introduce an option for item? maybe something likes -item:<name>=<value>? Which could produce

-item:Using=System.Net =>

<ItemGroup>
  <Using Include="System.Net" />
</ItemGroup>

For attribute, maybe -item:<name>=<value>,@<attrName>=<attrValue>

-item:Using=System.Net.IPNetwork,@Alias=SysIPNetwork =>

<ItemGroup>
  <Using Include="System.Net.IPNetwork" Alias="SysIPNetwork" />
</ItemGroup>

[KalleOlaviNiemitalo]

If a property is specified on the command line, then it is a global property, and MSBuild doesn't let it be changed in PropertyGroup (unless it's listed in the Project/@TreatAsLocalProperty attribute, or in the RemoveProperties parameter of the MSBuild task). AFAIK there is no similar concept of global items. Should there be?

[baronfel]

In order to take this, we would need to define

• the syntax for constructing the Items (and metadata)
• how globbing would work (and how shell globbing could impact this)
• the semantics of the added Items
  • should they be created once and injected only into the 'primary project' (even if that primary project is a generated solution metaproject?)
  • should they be created once and injected into every evaluated project that is part of the build?
  • some other otion I'm not thinking of
• how projects would opt out of this modification (similar to RemoveProperties and friends as @KalleOlaviNiemitalo points out)

To me, there are no clear answers to any of these points. We would need a detailed design before this would be approved. I'd encourage folks that want this to discuss and build that design (with input/guidance from the team as necessary) but there is no strong desire for this from the MSBuild team itself at this time.

[WeihanLi]

the syntax for constructing the Items (and metadata)

How does the proposal look?

-item:Using=System.Net.IPNetwork,@Alias=SysIPNetwork =>

<ItemGroup>
  <Using Include="System.Net.IPNetwork" Alias="SysIPNetwork" />
</ItemGroup>

how globbing would work (and how shell globbing could impact this)

Maybe we could just reject the globbing usage if there's no good practice so far

the semantics of the added Items

Think it should work like the property way, align with the property.

how projects would opt out of this modification (similar to RemoveProperties and friends as KalleOlaviNiemitalo points out)

How about beginning with a special character? Likes -item=-Using=System.Net means the <Using Include="System.Net" /> should be removed from the items.

[rainersigwald]

Can you expand a bit on what you'd use this functionality for?

[WeihanLi]

example use case like run file support: dotnet/sdk#49820