You may want to check out web2py. The windows executable includes python and does run without installation for example from a usb drive, like portable python. But it includes more goodies such as a web server, web based editor and plug and play web applications.
web2py is stable (currently version 1.46)
web2py exposes a python shell
web2py.exe -S yourappname -M
There is also a web based python shell available.
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It is an old post, so am wondering if the above Is still true, that I can use web2py to run scripts, etc?
Can I assume the web based python shell is similar to Idle?
Thank you.