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List:       python-list
Subject:    Re: map/filter/reduce/lambda opinions and background unscientific
From:       Steven Bethard <steven.bethard () gmail ! com>
Date:       2005-07-06 23:17:45
Message-ID: admdnV08AI8E-1HfRVn-hQ () comcast ! com
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Daniel Schüle wrote:
> Removing lamdba would be reduce readability of Python, I think here
> for examble of code like
> 
> class App:
>     ....
>     ....
>     def drawLines(self, event):
>         from random import randint
>         r = lambda : randint(1, 100)
>         self.canvas.create_line(r(), r(), r(), r())
> 
> defining one extra function would only confuse and

But you just did define one extra function!!

If you're really afraid of two lines, write it as:

     def r(): randint(1, 100)

This is definitely a bad case for an anonymous function because it's not 
anonymous!  You give it a name, r.

> and what about creating one liner factories like
> from math import log10
> log = lambda basis: lambda x: log10(x) / log10(basis)
> log2 = log(2)
> log2(2**10) -> 10.0

This is slightly better, because at least one of your functions really 
is anonymous.  I'm not really sure I'm convinced that it's any better 
than this though:

     def log(base):
         def log_in_base(x):
             return log10(x)/log10(base)
         return log_in_base

because when I first read the code, I didn't catch the second, nested 
lambda.  Of course, with a syntax-highlighting editor, I probably would 
have.

Again though, to fix your abuse of anonymous function syntax for 
non-anonymous functions, you should write this as:

     def log(basis):
         return lambda x: log10(x) / log10(basis)

Or if you're afraid of multiple lines:

     def log(basis): return lambda x: log10(x) / log10(basis)

STeVe
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