tl;dr “Foo” and “bar” as metasyntactic variables were popularised by MIT and DEC, the first references are in work on LISP and PDP-1 and Project MAC from 1964 onwards. Many of these people were in MIT’s Tech Model Railroad Club, where we find the first documented use of “foo” in tech circles in 1959 (and … Read more
From what I’ve been able to figure out, it seems like this is the case: _ is used to indicate that the input variable is a throwaway variable/parameter and thus might be required or expected, but will not be used in the code following it. For example: # Ignore a value of specific location/index for … Read more
While this question borders on being outside the scope of Stack Overflow, I highly recommend the Wikipedia article on the matter: The History of Foobar To give a quick preview: The word foo originated as a nonsense word from the 1930s, the military term FUBAR emerged in the 1940s… The term foo fighter was used … Read more
Yep, _ is a traditional name for “don’t care” (which unfortunately clashes with its use in I18N, but that’s a separate issue;-). BTW, in today’s Python, instead of: _,s = min( (len( values[s]), s) for s in squares if len(values[s]) > 1 ) you might code s = min((s for s in squares if len(values[s])>1), … Read more
_ has 3 main conventional uses in Python: To hold the result of the last executed expression in an interactive interpreter session (see docs). This precedent was set by the standard CPython interpreter, and other interpreters have followed suit For translation lookup in i18n (see the gettext documentation for example), as in code like raise … Read more