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Please translate this easy snip of C++ to Python

Fredrik Lundh fredrik at effbot.org
Sun Feb 4 15:24:01 EST 2001 
"Phlip" <phlip_cpp at my-deja.com> wrote:
> Ogle this awesome snip of C++:
>
>         #define TRACE_(x) cout << #x ": " << x << endl

That's a preprocessor trick, not a C++ trick.  Replace <<
with printf, and it works just as fine under C.

(iirc, bjarne thinks that real C++ programmers shouldn't
use the preprocessor at all, but what does he know...)

> How do I do that, just as easy to call, in Python?

Run your Python code through C's preprocessor?

Or use something like this:

    def trace(expr):
        # evaluate expression in callers namespace
        import sys
        try:
            raise None
        except:
            frame = sys.exc_info()[2].tb_frame.f_back
        print expr, "=", eval(expr, frame.f_globals, frame.f_locals)

    x = 10
    y = 20
    trace("x + y")

    ## prints:
    ## x + y = 30

Cheers /F

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