When I am in the Python or IPython console, what is called when I am returned an output?

Question

For example,

python
>> x = 1
>> x
1

I\'m curious about what method/function on x is returning 1. I\'m asking beca

Answer 1

The other answer addresses repr in a vanilla Python REPL, but it neglected to answer about IPython, which works quite differently and has many more features (and complexity) in regards to REPL printing.

Here's an example discrepancy:

# vanilla python:
>>> type([])


# in IPython:
>>> type([])
list

IPython has a custom pretty printer and public hooks for customizing repr within IPython. One such hook is _repr_pretty_ (single underscores!) and here's a basic example:

>>> class Widget:
...     def __repr__(self):
...         "vanilla"
...     def _repr_pretty_(self, p, cycle):
...         p.text("chocolate, strawberry")
...         
>>> Widget()
chocolate, strawberry

For more features, see "Integrating your objects with IPython" in the docs, in particular the Rich display section.