kj wrote:
>
>
> Consider the following Python snippet:
>
> SEPARATOR = '+'
>
> def spam(ham, eggs):
> """Return a hash of ham and eggs.
>
> The variables ham and eggs are tuples of strings. The returned
> "hash" is a dict made from the pairs returned by zip(ham, eggs).
> If ham contains repeated keys, the corresponding values in eggs
> are concatenated using the string "SEPARATOR".
>
> For example, spam(('a', 'b', 'a'), ('x', 'y', 'z')) returns
> {'a': 'xSEPARATORz', 'b': 'y'}."""
>
> # implementation follows...
>
>
> Of course, as written, the docstring above is no good. All
> occurrences of the string "SEPARATOR" in it should be replaced with
> the actual value of the global variable SEPARATOR, which in this
> case is the string '+'.
>
> My first attempt at achieving this effect was the following:
>
> SEPARATOR = '+'
>
> def spam(ham, eggs):
> """Return a hash of ham and eggs.
>
> The variables ham and eggs are tuples of strings. The returned
> "hash" is a dict made from the pairs returned by zip(ham, eggs).
> If ham contains repeated keys, the corresponding values in eggs
> are concatenated using the string "%(SEPARATOR)s".
>
> For example, spam(('a', 'b', 'a'), ('x', 'y', 'z')) returns
> {'a': 'x%(SEPARATOR)sz', 'b': 'y'}.""" % globals()
>
> # implementation follows...
>
>
> ...which, of course (in retrospect), does not work, since only a
> string literal, and not any ol' string-valued expression, at the
> beginning of a function's body can serve as a docstring.
>
> What's the best way to achieve what I'm trying to do?
A simple way is
spam.__doc__ = spam.__doc__ % globals()
which can easily be turned into a decorator:
def update_doc(f):
f.__doc__ = f.__doc__ % f.func_globals
return f
@update_doc
def spam(...):
...
Peter
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