Default value for options with ANY

[danimtb]

In options you can define a special value "ANY" as stated in the docs: https://docs.conan.io/en/latest/reference/conanfile/attributes.html#options-default-options

But in the example there is no default_options defined. Doing some tests Conan behaves like this:

• No default value: ERROR

conanfile.py

from conans import ConanFile

class MyConanFile(ConanFile):
    name = "MyConanFile"
    version = "1.0"
    options = {"shared": [True, False], "config": "ANY"}
    default_options = "shared=False",

$ conan create . danimtb/testing
ERROR: MyConanFile/1.0@danimtb/testing: 'config' value not defined

• No assigned value in default_options: WORKS

conanfile.py

from conans import ConanFile

class MyConanFile(ConanFile):
    name = "MyConanFile"
    version = "1.0"
    options = {"shared": [True, False], "config": "ANY"}
    default_options = "shared=False", "config="

$ conan create . danimtb/testing
...
MyConanFile/1.0@danimtb/testing: Package '5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9' created

But the generated conaninfo.txt has config= and conan search returns config: both without value.

• Use None as default value: Works

conanfile.py

from conans import ConanFile

class MyConanFile(ConanFile):
    name = "MyConanFile"
    version = "1.0"
    options = {"shared": [True, False], "config": "ANY"}
    default_options = "shared=False", "config=None"

$ conan create . danimtb/testing
...
MyConanFile/1.0@danimtb/testing: Package '5ab84d6acfe1f23c4fae0ab88f26e3a396351ac9' created

Generates conaninfo.txt with "config=None", conan search returns "config: None" and package ID is NOT affected.

I suggest to use the last option as default, encourage users to use "config": "ANY together with "config=None" default value and do not allow just "config=". Would be breaking but more clear.

[lasote]

I'm not sure why if an option admits any value has to automatically default to anything and not require a default like any other one.

[danimtb]

you could use a defaulted value if you want or even None, but just "config=" is something very weird

[memsharded]

"config=" is indeed weird.

What @lasote suggests is to change the current default behavior, and assign it a None value automatically without having to specify it in the conanfile, did I understand correctly?

[lasote]

You didn't understand correctly. I was asking why we should do that for the ANY options and not for others.
I think the feature should be: raise when "config=" and allow "config=None"

[danimtb]

Yes, that is what I suggested in the original comment. By:

I suggest to use the last option as default, encourage users to use "config": "ANY together with "config=None" default value and do not allow just "config=".

I meant: "I suggest to use the last case indicated above" -> raise when "config=" and allow "config=None"

[ericLemanissier]

Just to be sure, you expect all recipes to handle the "config would be empty" case in the following way:
if self.options.config == "None": instead of the current if self.options.config: ?

[lasote]

@ericLemanissier no, this is not related.

[danimtb]

@ericLemanissier it should be if self.options.config: and default value when "config=None" should be NoneType

[ericLemanissier]

ok, my bad, if self.options.config: takes the else branch when default_options= "config=None"
However str(self.options.config) is equal to the "None" string, instead of being an empty string

[lasote]

@ericLemanissier probably you are right, @danimtb performed some tests and default_options= "config=None" => self.options.config == "None" and self.options.config != None
I think this is a bug but a little dangerous.

[danimtb]

@ericLemanissier at least if you declare:

from conans import ConanFile

class MyConanFile(ConanFile):
    name = "MyConanFile"
    version = "1.0"
    options = {"config": "ANY"}
    default_options = "config=None"

if self.options.config: should be false as you reported. It is evaluated as False.