LpConstraint name is not set on initialisation

[christiansegercrantz]

Details for the issue

Somewhere in #750 it seems the ability to set the name for LpConstraints has been lost. It's also obvious from the code that the name for the constraint is not set, it's at maximum set for the LpAffineExpression. @MBradbury I assume this wasn't intentional, or? If it wasn't, we should probably add back the possibility to give the constraint a name. I'm happy to do it as long as I get some guidance on how to do it. I'd assume, we'd always use the name given as the LpConstraint name and only, as currently, use the same name for the expression if it wasn't a LpAffineExpression to start with.

What did you do?

from pulp import (
    LpAffineExpression,
    LpConstraint,
)

test = LpAffineExpression(1)
print(f"{test.name=}")

test2 = LpConstraint(test, name="Test2")
print(f"{test2.name=}")

print(f"{test2.expr.name=}")

What did you expect to see?

test.name=None
test2.name="Test2"
test2.expr.name=None

What did you see instead?

test.name=None
test2.name=None
test2.expr.name=None

Additionally

from pulp import (
    LpAffineExpression,
    LpConstraint,
)

test = LpAffineExpression(1, name="Test1")
print(f"{test.name=}")

test2 = LpConstraint(test, name="Test2")
print(f"{test2.name=}")

print(f"{test2.expr.name=}")

produces

from pulp import (
    LpAffineExpression,
    LpConstraint,
)

test = LpAffineExpression(1, name="Test1")
print(f"{test.name=}")

test2 = LpConstraint(test, name="Test2")
print(f"{test2.name=}")

print(f"{test2.expr.name=}")

Useful extra information

What operating system are you using?

• Windows: ( version: ___ )
• Linux: ( distro: ___ )
• Mac OS: macOS Sequoia 15.3 (24D60)
• Other: ___

I'm using python version:

• 3.7
• 3.8
• 3.9
• 3.10
• 3.11
• Other: [email protected]

I installed PuLP via:

• pypi (python -m pip install pulp)
• github (python -m pip install -U git+https://github.com/coin-or/pulp)
• Other: rye add pulp --git https://github.com/coin-or/pulp

Did you also

• Tried out the latest github version: https://github.com/coin-or/pulp
• Searched for an existing similar issue: https://github.com/coin-or/pulp/issues?utf8=%E2%9C%93&q=is%3Aissue%20

[MBradbury]

I have a fix for this on another branch (https://github.com/MBradbury/pulp/tree/typehints), have extracted it out and made #806.

For your test I now get:

test.name=None
test2.name='Test2'
test2.expr.name=None

test.name='Test1'
test2.name='Test2'
test2.expr.name='Test1'