Hi With my editor cap on, I am working my way through the documentation. The section on lambda, in the python language section of the book, makes me uncomfortable. It says this:
*** The existence of lambda allows re-factoring an existing function in terms of a different set of arguments. cache.ram and cache.disk are web2py caching functions. *** It is implied that the lambda keyword allows currying, when in fact that functionality is provided by standard Python functions. For example (using the example given in the text), >>> def f(a, b): return a + b >>> g = lambda a: f(a, 3) >>> g(2) 5 Could be written without lambda as >>> def f(a,b): return a + b >>> def g(a): return f(a, 3) >>> g(2) 5 The anonymity of lambda means that inline code is allowed, because no prior declaration is needed in order to obtain a reference, as is the case with def, but on the other hand, lambdas are limited to a single expression, whereas def functions are not. Consider the next example: >>> number = 7 >>> print cache.ram(str(number), lambda: isprime(number), seconds) True >>> print cache.ram(str(number), lambda: isprime(number), seconds) True Could be rewritten as >>> number = 7 >>> def isprimecall: return isprime(number) >>> print cache.ram(str(number), isprimecall, seconds) True >>> print cache.ram(str(number), isprimecall, seconds) True In conclusion, the description of lambda in the text is misleading. Comments?
