[API Proposal]: StringSyntaxAttribute.Guid

[NN---]

Background and motivation

There is already StringSyntaxAttribute.GuidFormat but there is no syntax for GUID.

a proposal is to add StringSyntaxAttribute.Guid which expects GUID in one of allowed formats which Guid.Parse understands: B, D, X.

API Proposal

namespace System.Collections.Generic;

public class MyFancyCollection<T> : IEnumerable<T>
{
    public void Fancy(T item);
}

API Usage

void f([StringSyntaxAttribute.Guid)] string guid){}

Alternative Designs

No response

Risks

No risk

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Tagging subscribers to this area: @tommcdon
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Issue Details

---

Background and motivation

There is already StringSyntaxAttribute.GuidFormat but there is no syntax for GUID.

a proposal is to add StringSyntaxAttribute.Guid which expects GUID in one of allowed formats which Guid.Parse understands: B, D, X.

API Proposal

namespace System.Collections.Generic;

public class MyFancyCollection<T> : IEnumerable<T>
{
    public void Fancy(T item);
}

API Usage

void f([StringSyntaxAttribute.Guid)] string guid){}

Alternative Designs

No response

Risks

No risk

Author:	NN---
Assignees:	-
Labels:	api-suggestion, area-System.Diagnostics, untriaged
Milestone:	-

[tommcdon]

@ericstj @karelz

[ericstj]

It looks like this is related to #62505 and #65634

GuidFormat is only for specifying the format specifiers and we don't have anything that would validate a string for actual GUID syntax.

@stephentoub @CyrusNajmabadi it looks like you were involved with this feature during 7.0 - any thoughts on the request?

[stephentoub]

I'd be interested in seeing some examples where we expect this would be used, e.g. beyond Guid.Parse and friends, what APIs are taking guids as strings rather than Guids (and why)? But assuming there's a reasonable number of them, it'd be reasonable to add this.

[NN---]

If it was possible to specify the validation using regular expression and not by only predefined types, this feature would be generic enough to cover almost any need.

E.g.
[StringSyntax(@"\d{4}-\d{4}")] string twoNumbers

[CyrusNajmabadi]

So, from the roslyn perspective, what we're working on is making this an extensible system. For example, the ASP.Net 'route syntax' support is provided through a plugin provided by the asp.net team. This takes the costs off of us, and allows API owners to determine if they want to invest in this space.

We are committed to Regex and Json, but we're not likely to add more languages ourselves. In a case like this, we would just expose the same extensibility point and let the Guid owners decide if they wanted to add anything here.

[Joe4evr]

beyond Guid.Parse and friends, what APIs are taking guids as strings rather than Guids (and why)?

S.R.IS.GuidAttribute? Or did you already count that as a "friend"?

[stephentoub]

Or did you already count that as a "friend"?

I was thinking of it as a "friend". Mainly I'm wondering about use outside of the core libraries.