Add an option to not panic on value*of() of non valid arguments

[lu-zero]

Please complete the following tasks

• I have searched the discussions
• I have searched the open and rejected issues

Clap Version

clap-3.1.8

Describe your use case

The cargo feature exposes is_valid() as workaround but it makes quite cumbersome to deal with code that has similar needs.

Describe the solution you'd like

Adding a setting to simply return None would spare quite a bit of boilerplate.

Alternatives, if applicable

Make so the cargo feature re-enable the former behavior.

Additional Context

No response

[epage]

It'd help if you explained why you don't want arguments validated.

Make so the cargo feature re-enable the former behavior.

What does the cargo feature have to do with this request?

[lu-zero]

The use case is the same as cargo's, the cargo feature is already there to accommodate the needs of cargo.

[epage]

The use case is the same as cargo's

Can you go into more detail. What are you doing, how, and why. Understanding what people are trying to accomplish with a request is important for shaping features.

the cargo feature is already there to accommodate the needs of cargo.

The cargo feature is for not for the needs of cargo. In fact, cargo doesn't enable it.

From the README

cargo: Turns on macros that read values from CARGO_* environment variables.

Example of something relying on this feature: https://docs.rs/clap/latest/clap/macro.command.html

[lu-zero]

The use case is the same as cargo's

Can you go into more detail. What are you doing, how, and why. Understanding what people are trying to accomplish with a request is important for shaping features.

cargo has multiple applets and some codepaths are common and they rely now on is_valid() to simulate what previously was simply the use of value_of() and managing the None path.

the cargo feature is already there to accommodate the needs of cargo.

The cargo feature is for not for the needs of cargo. In fact, cargo doesn't enable it.

From the README

Sorry, I meant treat it as the is_valid*() set of functions that cargo uses.

[epage]

cargo has multiple applets and some codepaths are common and they rely now on is_valid() to simulate what previously was simply the use of value_of() and managing the None path.

Yes, I'm the one who ported cargo to clap3 and added is_valid for that purpose.

I'm taking it from your comments that you are depending directly on cargo and are re-using its flag definitions and flag reading?

[lu-zero]

yes.

[epage]

Huh, for some reason I created an issue for finding a longer term solution for cargo but I can't find it. Guess we'll use this for tracking that then.

[lu-zero]

Thank you :)