Example of Lisp Macros

Just don't upmod it. If you're lucky it will go away.

That said, there are many who are interested in the topic (me included) as demonstrated by the comments.

Relax and upmod the submissions that you like. News is only as relevant as the community decides. :)

(with-input-file (in "myfile.txt") (do-something in))

In Python, this might look like

withInputFile in "myfile.txt": doSomething(in)

(hey, I told you I was rusty on my Python...especially my totally made up Python!)

So maybe the feature came built-in to Python, in which case you're lucky--Guido happened to decide to implement this feature. But what if he hadn't? Well, just write your own abstraction. Obviously, Python can open files and do stuff with the file's contents. So it seems logical that you should be able to create an abstraction which saves you from writing the same boilerplate that you do every time you open an input file. Unfortunately, there are some abstractions that *you just can't write* in most languages (including Python). This file open example is a good one. Here's another example, in the form of a programming challenge:

In Python, create an abstraction called "debugExpr" that consumes an expression E, and then does two things: 1) prints "Expression E = V", where E is the given expression, and V is the value E evaluates to. 2) returns the value V.

For example,

%python% 6 * debugExpr(2+3)

Expression 2+3 = 5

30

I'm betting you can't implement debugExpr in Python. So assuming Guido didn't extend the language to implement this feature, you're pretty much SOL. It's a shame because debugExpr, I think, is pretty darn useful. It means that you can take any expression in your code and "inspect it", without worrying about adjusting the structure of your program, and without affecting its semantics. Without debugExpr, I'd have to change my example code to be something like this to get the same result:

print "Expression 2+3 ="

tmp = 2+3

print tmp

6 * tmp

YUCK!