Champion "CallerArgumentExpression"

[gafter]

Allow developers to capture the expressions passed to a method, to enable better error messages in diagnostic/testing APIs and reduce keystrokes.

• Proposal added caller-argument-expression.md
• Discussed in LDM 2017-05-16
• Decision in LDM
• Finalized: Done
• Spec'ed

See #205

[HaloFour]

If expansion of the supported caller info attributes is going to be discussed in the LDM is there a chance that some quantity of #87 be mentioned as well?

[CyrusNajmabadi]

@HaloFour I think that would be reasonable. If we're going to do more in this space, we probably want to do it all at once.

[jamesqo]

Related corefx proposal that would take advantage of this feature: dotnet/corefx#17068

[jamesqo]

@CyrusNajmabadi

I think that would be reasonable. If we're going to do more in this space, we probably want to do it all at once.

Do I need to modify the proposal I'm working on to include his suggestions, or will they be reviewed just by looking at the issue?

[gafter]

My intent is to bring up this one request to the design group. It sounds like @CyrusNajmabadi will bring up the others in that discussion.

[alrz]

Related: #443

void M(object param, [CallerArgumentExpression(nameof(param))] string arg = null) {}

[jamesqo]

@alrz I agree with the proposal, but it isn't strictly necessary for this to move forward. The end user will not have to touch this attribute. Only a handful of methods in the framework will use it, and for those it's fine to simply hard-code the string.