How to assign the result of the previous expression to a variable?
.Last.value is an answer. It was answered once but you have better title.
built-in
How to add builtin functions?
In short, it is technically possible to add things to Python’s builtins†, but it is almost never necessary (and generally considered a very bad idea). In longer, it’s obviously possible to modify Python’s source and add new builtins, keywords, etc… But the process for doing that is a bit out of the scope of the … Read more
Naming conflict with built-in function
Step one: rebind the list to a different name lst = list Step two: delete the list variable del list Step three: don’t do it again I prefer this over __builtins__.list simply because it saves the typing, and you aren’t still left with a variable named list. However, it is always best to avoid the … Read more
What is the difference between a language construct and a “built-in” function in PHP?
(This is longer than I intended; please bear with me.) Most languages are made up of something called a “syntax”: the language is comprised of several well-defined keywords, and the complete range of expressions that you can construct in that language is built up from that syntax. For example, let’s say you have a simple … Read more
Performance of built-in types : char vs short vs int vs. float vs. double
Float vs. integer: Historically, floating-point could be much slower than integer arithmetic. On modern computers, this is no longer really the case (it is somewhat slower on some platforms, but unless you write perfect code and optimize for every cycle, the difference will be swamped by the other inefficiencies in your code). On somewhat limited … Read more
What’s the function like sum() but for multiplication? product()?
Actually, Guido vetoed the idea: http://bugs.python.org/issue1093 But, as noted in that issue, you can make one pretty easily: from functools import reduce # Valid in Python 2.6+, required in Python 3 import operator reduce(operator.mul, (3, 4, 5), 1)
How is the ‘is’ keyword implemented in Python?
Testing strings with is only works when the strings are interned. Unless you really know what you’re doing and explicitly interned the strings you should never use is on strings. is tests for identity, not equality. That means Python simply compares the memory address a object resides in. is basically answers the question “Do I … Read more
What is the purpose of the : (colon) GNU Bash builtin?
Historically, Bourne shells didn’t have true and false as built-in commands. true was instead simply aliased to :, and false to something like let 0. : is slightly better than true for portability to ancient Bourne-derived shells. As a simple example, consider having neither the ! pipeline operator nor the || list operator (as was … Read more