What is the effect of `at` operator?

[a-takahashi223]

• I am on the latest Poetry version.

• I have searched the issues of this repo and believe that this is not a duplicate.

• If an exception occurs when executing a command, I executed it again in debug mode (-vvv option).

• OS version and name: CentOS Stream

• Poetry version: 1.1.13

• Link of a Gist with the contents of your pyproject.toml file: None

Issue

The documentation says

When adding dependencies via poetry add, you can use the @ operator. This is understood similarly to the == syntax, but also allows prefixing any specifiers that are valid in pyproject.toml.

And it shows the example that poetry add django@^4.0.0 will add the line Django = "^4.0.0" to pyproject.toml. But what version is installed (written to poetry.lock) is not shown.
As "@ operator is understood similarly to the == syntax", django 4.0.0 is expected to be installed. But no.

$ poetry show django
name         : django
version      : 4.0.6

This result seems to be the same as poetry add django^4.0.0. What is the difference? What is the effect of @ operator?

#3142 and #5136 is the similar questions, and #5822 says it solved them, but I can't understand the effect of @ operator by reading the documentation.

[a-takahashi223]

I tried some other patterns.

django@4.0.0 is the same as django==4.0.0.
django@latest add the dependency django = "^4.0.6" for now, the same as django (no specifiers). django^latest is not allowed.
django@^latest is not allowed.

So

• django@latest is the same as django (no specifiers)
• django@x.y.z is the same as django==x.y.z
• In other case, @ is simply ignored (as mentioned in What does the @ in poetry add pendulum@^2.0.5 in a docs example mean? #5136 (comment) )

Is there any case that does not follow the rules above?

[finswimmer]

Hello @a-takahashi223,

I think you overlook the ^ in django@^4.0.0. The caret operator is described in the docs. In this case django@^4.0.0 would be equal to django>=4.0.0,<5.0

fin swimmer

[a-takahashi223]

so django>=4.0.0,<5.0 is equal to django^4.0.0, then django@^4.0.0 is equal to django^4.0.0?

[Secrus]

The @ operator is described in docs for version 1.2, as this is the main focus right now.

[github-actions]

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