Go is boring - Hackdot

Re:Go is boring by icebraining on Friday July 27, 2012 @12:39PM (#4302231)

I don't understand. You can't pickle functions; when you pickle a function, you get a reference to the function, not the actual function code.

E.g., this doesn't work:

    Dump.py:
      def isEven(n):
          return n % 2 == 0
      import pickle
      with open('pickled','w') as dumpfile:
          pickle.dump(isEven, dumpfile)

    Loader.py
      import pickle
      with open('pickled') as loadfile:
          isEven = pickled.load(loadfile)

This throws

    AttributeError: 'module' object has no attribute 'isEven'

What you can do is marshal the function's code:

    import marshal
    marshal.dump(isEven.func_code, file)
    #Then to load
    isEven = types.FunctionType(marshal.load(file), globals())

But you can also dump a lambda's code:

    import marshal
    marshal.dump((lambda n: n % 2 == 0).func_code, file)
    #Loading is the same
    isEven = types.FunctionType(marshal.load(file), globals())
    isEven(4)

So frankly, I don't get the problem with lambdas.

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Re:Go is boring by hythloday on Friday July 27, 2012 @01:12PM (#4302431)

When you pickle a function, you get a reference to the function, not the actual function code.

Right - that's usually what I want. (I've used pickle to store tests against game assets, e.g. that a model has all of its textures checked into perforce, or that a texture for a model does not exceed 128x128, unless otherwise specified). Marshalling functions is usually a non-starter for this, since a) it's complicated to analyse the call graph before execution, and b) native functions can't be marshalled - an awful lot of code executed against this asset pipeline is thin bindings over native/Java/C# code. Maybe I have found the 1% of the Python use-cases where lambdas suck a bit and everywhere else it's fine--it would be great if my experience was exceptional and no-one else had ever had a similar problem doing something else.

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Re:Go is boring by icebraining on Friday July 27, 2012 @01:20PM (#4302474)

Oh, ok. I don't know how Python could pickle a reference to an anonymous function, 'though.

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