Why use NETStandard.Library as a dependency instead of explicitly defining what you use from the BCL (NETStandard.Library)

Chat extract from Slack

https://aspnetcore.slack.com/archives/dotnet-core/p1481195518000050

johnkors [12:11 PM]  
what do I, as a library author, gain by depending on `NETStandard.Library` instead of explicitly _just_ the nugets I need? (edited)

johnkors [12:26 PM]  
- Some do : https://www.nuget.org/packages/xunit.abstractions/ @bradwilson 
- Others don't : https://www.nuget.org/packages/Newtonsoft.Json/9.0.1 , @jamesnk

Wonder what's "better"; or why one would prefer one over the other. (edited)

thomascastiglione [12:48 PM]  
you will soon be semi-required to depend on netstandard.library

[12:48]  
it is becoming an automatic thing that isn't explicitly specified

[12:48]  
microsoft's original plan was that people would use granular deps to reduce deployment sizes

[12:49]  
but after initial release and feedback it turned out this was not very useful for many people and a big hassle

[12:49]  
so the plan these days is to not bother

[12:49]  
except when you REALLY need to

[12:49]  
additional tools are being developed to reduce deployment sizes a different way

[12:49]  
a 'linking' step which removes components of the library that weren't used

tore.lervik [12:56 PM]  
So moving the action from user choice to build automation would be nice.

johnkors [1:18 PM]  
> you will soon be semi-required to depend on netstandard.library
> it is becoming an automatic thing that isn't explicitly specified

How so, exactly..?

[1:19]  
> but after initial release and feedback it turned out this was not very useful for many people and a big hassle
.. because..? the BCL won't change that much? or often?

thomascastiglione [1:23 PM]  
how so: in new-csproj, when you use the netstandardxx tfm, it will automatically reference the NETStandard.Library package

[1:23]  
unless explicitly removed or overridden

johnkors [1:24 PM]  
ah, for _new_ projects. OK

thomascastiglione [1:24 PM]  
yep

[1:24]  
well

[1:24]  
also for existing ones that get migrated!

johnkors [1:24 PM]  
true :smile:

thomascastiglione [1:24 PM]  
it's not a template thing

[1:24]  
it's an actual feature of the sdk

[1:24]  
if you DO want to omit it you still can with the normal msbuild syntax for removing an Item, `<PackageReference Remove="NETStandard.Library"/>`

[1:24]  
but  i don't think many people will do that

[1:24]  
(or even be aware that it is an option)

[1:25]  
you could override the version, similarly, with `<PackageReference Update="NETStandard.Library" Version="whatever.whatever"/>`, so full flexibility will remain

[1:26]  
as for why it wasn't useful, i think it's because most people are running .net core programs on machines with a .net core runtime installed, rather than standalone..

[1:26]  
and the runtime comes with all the packages in the stdlib

[1:26]  
so there was nothing actually gained most of the time

[1:26]  
just complexity added

johnkors [1:28 PM]  
hmm.. So, as a consumer of a nuget, I usually don't care what parts of the BCL is used, because i've most likely installed the runtime where I run my apps...? That's what you're saying?

thomascastiglione [1:28 PM]  
yep

[1:28]  
the whole BCL is generally present on the machine

[1:29]  
(and is not duplicated into the app or anything)

johnkors [1:29 PM]  
:+1:

[1:29]  
so it's only a "issue" if you're creating standalone apps & really care about deploy size..?

thomascastiglione [1:30 PM]  
yeah, at which point you might need to use a more complex project file to remove the implicit reference

[1:30]  
(or wait for the linker tool)

johnkors [1:31 PM]  
ah, so it actually get's harder(-ish) to omit the `NETStandard.Library` at some point as well.

thomascastiglione [1:31 PM]  
i've got to go for now, but here's a github issue where the implicit reference behaviour is being discussed https://github.com/dotnet/sdk/pull/450
 GitHub
Implicitly add PackageReference for NETStandard.Library if targeting .NET Standard by dsplaisted · Pull Request #450 · dotnet/sdk · GitHub
This PR will implicitly add a PackageReference to NETStandard.Library if the project is targeting .NETStandard and there isn't already a PackageReference to NETStandard.Library. This makes project... 
 
 

[1:31]  
not quite a final design as you can see from the discussion there

johnkors [1:33 PM]  
Thx a lot for your time! :slightly_smiling_face:

[1:33]  
subscribing to that issue