Years ago, I interviewed the head of a large public housing authority about the mixed-income properties that her agency was developing. I asked to be put in touch with a public housing resident living in one of these new communities. It’s a common request granted to Affordable Housing Finance all the time, but, in this case, the executive balked. She was hesitant because they were creating a place where poor public housing residents lived without stigma next door to middle-income families. No one was supposed to know which neighbors were public housing residents.

A much different attitude has surfaced at a Manhattan ­development. One of the big stories in recent weeks involves the “poor door” at a 33-story development under construction on the Upper West Side. The property will feature pricey condos, with wealthy residents going in and out of the main entrance. The building will also have a segment featuring 55 affordable housing units with a separate door for the low-income families.

The developers haven’t broken the rules. Even so, the idea of separate doors is insensitive at best. At worst, it’s a form of discrimination, an affront to the “melting pot” dynamic that characterizes the Big Apple.

City leaders have pledged to review their housing programs and reconsider what should be allowed in exchange for building desperately needed affordable housing. Of course, they should close loopholes that allow for distasteful poor doors. And, they should continue to support strong inclusionary housing programs that result in mixed-income housing.

Earlier this year, Mayor Bill de Blasio called for the construction or preservation of 200,000 affordable units over the coming decade, and he pledged to help break down financial barriers of entry toward that end.

But this story adds another wrinkle to that effort: It turns out he’ll have to kick down some doors too.