Jan Riechers wrote: > I have one very basic question about speed,memory friendly coding, and > coding style of the following easy "if"-statement in Python 2.7, but Im > sure its also the same in Python 3.x > > Block > #---------------------------------- > if statemente_true: > doSomething() > else: > doSomethingElseInstead() > > #---------------------------------- > > versus this block: > #---------------------------------- > if statement_true: > doSomething() > return > > doSomethingElseInstead() > > #---------------------------------- > > > I understand the first pattern that I tell the interpreter to do:
A common misconception. As a writer of Python source code, (usually) you never tell the (CPython) interpreter anything (but to start working on the source code). Python source code is automatically *compiled* into bytecode by the (CPython) interpreter, and that bytecode is executed by a virtual machine.¹ So at most, you are telling that virtual machine to do something, through the bytecode created from your source code. > Check if the conditional is true, run "doSomething()" else go inside the > else block and "doSomethingElseInstead()". > > while the 2nd does only checks: > doSomething() if statement_true, if not, just go directly to > "doSomethingElseInstead() > > > Now, very briefly, what is the better way to proceed in terms of > execution speed, readability, coding style? Since this is comp.lang.python, you just need to check against the Zen of Python to know what you should do ;-) <http://www.python.org/dev/peps/pep-0020/> For me, this boils down in this case to the common recommendation "return early, return often" as "explicit is better than implicit" and "readability counts". If there is nothing else than the `else' block in the function, there is no use for you to continue in the function, so you should return explicitly at this point. On the other hand, if you can *avoid repeating code* in each branch by _not_ returning in the first branch, you should do that instead ("practicality beats purity"). HTH _____ ¹ This is not unlike in other so-called "scripting languages"; although for reasons that escape me, the software that compiles the source code – the compiler – is called the (C)Python *interpreter*, even in <http://docs.python.org/faq/general.html>. -- PointedEars Please do not Cc: me. / Bitte keine Kopien per E-Mail. -- http://mail.python.org/mailman/listinfo/python-list
