I like pull-ups. They are an important part of most athletic training for upper body development. You should never live somewhere you cannot do pull ups. A home without a pull-up bar in the modern world confuses me as much as a home without electricity or running water. Unfortunately, not all landlords agree so before I bought my first house I had to build a solid pull-up bar in my apartments. This mechanism pressure-fits between the studs in a hallway to provide horizontal stability in two directions. Vertical stability is provided by 2x4s which rest on the flooring.
To prevent the plywood from scraping up the wall I recommend taping a sheet of wax paper to the wall, then a towel, then the plywood compression mechanism. The towel provides a cushion and the wax paper prevents the towel from bonding with the paint on the drywall which can happen if the towel is compressed into the paint for months or years.
Hazards If you use a steel bar which is not girthy enough relative to its length to support your weight without bowing, this system will fall apart as you apply your bodyweight. I used a 2" piece of gas pipe across a 4 foot span which easily supported 300 lbs. Design carefully, test carefully, and you should be fine.
I welded the angle and 2.5" 11 guage square together before bolting them to the plywood. This is not necessary as none of the joints between those pieces are under load. The 11 guage square could just as easily be glued to the plywood with epoxy or Gorrilla glue.
[Caption] Pressure-fit pull-up bar plans as dxf. These three components are made from 3/4" plywood. The holes on the right two pieces allow three 1/2" bolts to apply outward pressure against the walls. The central 2.5" square 11 guage sheet metal on the front prevents the pipe from cutting into the plywood under pressure.