In article <[EMAIL PROTECTED]>,
Paul McGuire <[EMAIL PROTECTED]> wrote:
>Well, I'm not sure "closure" is the Pythonic way. But in Python, you
>can use functions to dynamically create other functions. Here's an
>example of this feature (although there are far simpler ways to do
>this), tallying vowels and consonants in an input string by calling a
>function looked up in a dictionary. Note that tallyFn creates a
>temporary function that uses the 'key' argument passed into tallyFn,
>and then returns the temporary function. Perhaps this idiom can serve
>in place of your concept of closures for small anonymous functions.
>
>-- Paul
>
>(replace the leading .'s with spaces - I'm posting with Google Groups):
>
># global tally structure
>tally = {}
>tally["consonant"] = 0
>tally["vowel"] = 0
>tally["not sure"] = 0
>tally["none"] = 0
>
># function to construct other functions (instead of closures)
>def tallyFn( key ):
>....def addToTally():
>........tally[key] = tally[key] + 1
>....return addToTally
>
># create dict of functions
>functions = {}
>functions["a"] = tallyFn("vowel")
>functions["b"] = tallyFn("consonant")
>functions["c"] = tallyFn("consonant")
>functions["d"] = tallyFn("consonant")
>functions["e"] = tallyFn("vowel")
>functions["f"] = tallyFn("consonant")
>functions["g"] = tallyFn("consonant")
>functions["h"] = tallyFn("consonant")
>functions["i"] = tallyFn("vowel")
>functions["j"] = tallyFn("consonant")
>functions["k"] = tallyFn("consonant")
>functions["l"] = tallyFn("consonant")
>functions["m"] = tallyFn("consonant")
>functions["n"] = tallyFn("consonant")
>functions["o"] = tallyFn("vowel")
>functions["p"] = tallyFn("consonant")
>functions["q"] = tallyFn("consonant")
>functions["r"] = tallyFn("consonant")
>functions["s"] = tallyFn("consonant")
>functions["t"] = tallyFn("consonant")
>functions["u"] = tallyFn("vowel")
>functions["v"] = tallyFn("consonant")
>functions["w"] = tallyFn("consonant")
>functions["x"] = tallyFn("consonant")
>functions["y"] = tallyFn("not sure")
>functions["z"] = tallyFn("consonant")
>functions[" "] = tallyFn("none")
>functions["."] = tallyFn("none")
>
>testdata = """
>The quick brown fox jumps over the lazy dog.
>Now is the time for all good men to come to.
>Many hands make light work heavy.
>"""
>
>for line in testdata.split("\n"):
>....for c in line.lower():
>........fn = functions[c]
>........fn()
>
>print tally
>
>Gives:
>{'none': 26, 'consonant': 59, 'not sure': 3, 'vowel': 33}
>
Help me. While I recognize you're looking to construct a
pedagogically-meaningful example, all that typing makes me
wonder what lesson we're teaching. To me, it's more in the
spirit of python to have a
if c in "aeiou":
...
elif c in "bcdfghjklmnpqrstvwxz":
...
elif c == "y":
...
in there somewhere. What am I missing about your dictionary
construction?
It's hard for me to type the same variable reference repeatedly.
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