[Python-Dev] def ... decorate (original) (raw)
Roman Suzi rnd at onego.ru
Fri Aug 13 18:24:21 CEST 2004
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On Fri, 13 Aug 2004, Skip Montanaro wrote:
with
def pstatementexpr: staticmethod grammarrule('statement : expression') version("Added in 2.4") deprecatedmethod type(None) decorate (self, p): """docstring here""" print p[1]
Bingo!
Just replace decorate with "from" and the nice syntax is found:
def f:
staticmethod
grammarrule('statement : expression')
version("Added in 2.4")
deprecatedmethod
type_(None)
from self, p:
"""docstring here"""
print p[1]- doesn't surprise Python programmer, because it is like try-except, etc
- reads a natural language (with implicit "with" after "f")
- doesn't require any new keywords or symbols and "prefix" operators
- is explicit about transformation
- no additional indentation
- grepping for defs now require more effort, so probably second name should be allowed after "from" or exactly this.
As a variant, docstring could be moved to the upper part.
I'd also liked being able to write:
def f: staticmethod; grammarrule('statement : expression') version("Added in 2.4"); deprecatedmethod; type_(None) from x, y: pass #...
and:
def f: staticmethod from x, y: return x+y
It seems different enough from other solutions that I thought it worth tossing out. I didn't see it mentioned in the PythonDecorators moin page.
Read it something like "define a function named pstatementexpr using a bunch of functions to decorate the basic function". It solves a couple problems: 1. "def" introduces the function definition instead of an arbitrary number of @-expressions. 2. There is no extra indentation of the main body. 3. The name of the function is known early on. 4. "def"/"decorate" pair up visually much the same as "try"/"except" or "if"/"then", though they don't represent alternative blocks of code to be executed. On the minus side it introduces a vertical separation between the function name and parameter list and introduces a new keyword, "decorate".
From a parsing standpoint I think it will work. You'll see either a colon or a left paren after the function name to distinguish between the two types of function definition. I'm not sure if a token needs to be used to separate the various decorator functions or if requiring a newline and indentation is sufficient. Skip
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Sincerely yours, Roman Suzi
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