Error if %s is not present in prompt string format

[fcollonval]

Hey,

I was trying to hide the prompt by setting an empty string to nbsphinx_input_prompt. This results in a TypeError on:

nbsphinx/src/nbsphinx.py

Line 1065 in 77f305b

prompt = prompt_template % (execution_count,)

The blame is the % format. Would you consider switching to format asking user to set the string as "In [{}]" rather than "In [%s]". This will be more robust, see:

In [6]: "hello" % "dummy"
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-6-a2bd27e7e4d9> in <module>
----> 1 "hello" % "dummy"

TypeError: not all arguments converted during string formatting

In [7]: "hello".format("dummy")
Out[7]: 'hello'

In [8]: "hello {}".format(12)
Out[8]: 'hello 12'

Another possibility would be to test for %s.

Note: I use that workaround for my initial purpose.

[mgeier]

Thanks for the suggestion!

This would be a breaking change though, and would make many users angry, so I would need a really good reason to do it.

I was trying to hide the prompt by setting an empty string to nbsphinx_input_prompt.

I wouldn't recommend hiding the prompts in the first place, but if you insist, you still shouldn't do it with nbsphinx_input_prompt.

For a more reliable method, see https://nbsphinx.readthedocs.io/en/latest/custom-css.html.

[fcollonval]

This would be a breaking change though, and would make many users angry, so I would need a really good reason to do it.

Ya I thought so. This is why I suggested testing for %s in the string to make it more robust without breaking change 😉

Thanks for the additional information. You rock at supporting users 🥇

[mgeier]

Thanks!

I don't fully understand your proposal.
Do you mean nbsphinx should check whether nbsphinx_input_prompt contains '%s' and then, depending on that use either % or .format()?

Can you please elaborate?

[mgeier]

Thanks, #446 clears up what you mean!