Multiplication is not equivalent when multiplying offset units by a float and dimensionless Quantity.

[mile-gepek]

from pint import UnitRegistry

ureg = UnitRegistry(autoconvert_offset_to_baseunit=True)

print(100 == ureg.Quantity(100)) # True

celsius = ureg.Quantity("celsius")

hundred_celsius = 100 * celsius
print(hundred_celsius)  # 100 C

hundred_celsius = ureg.Quantity(100) * celsius
print(hundred_celsius)  # 27414 kelvin

Given Quantity(100) is equal to the int/float 100, I'd expect it to behave the same when multiplying by an offset unit, but it seems to autoconvert to kelvin instead, and only then multiply by a 100.

[dalito]

This is documented and by design for mode autoconvert_offset_to_baseunit = True (the I-insist-to-shoot-in-my-foot option).

Note that you have two different multiplications: float * Quantity and Quantity * Quantity

[mile-gepek]

From https://pint.readthedocs.io/en/latest/api/base.html:

autoconvert_offset_to_baseunit – If True converts offset units in quantities are converted to their plain units in multiplicative context. If False no conversion happens.

Is multiplying by an int/float not a multiplicative context?

I can't find anything about multiplication by a float and dimensionless quantity behaving differently by design.

[dalito]

Is multiplying by an int/float not a multiplicative context?

Yes THIS is the context for which the option was created many years ago. However, multiplying two quantities is another context and different in code path. I think the surprise comes from assuming that a dimensionless quantity is the same as a float/int. The issues/PRs from the time this was added give more background if you want to dive deep.

[mile-gepek]

I think the surprise comes from assuming that a dimensionless quantity is the same as a float/int.

Well, are they not the same if they are equal?

If you have an issue/PR number I'm down to read, I've dug around but I can't find anything on this.