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None. Standard interpreter automatically compiles modules to bytecode on the first import and stores them in .pyc files. Compiling specific files is also possib

by trwired 11y ago

None. Standard interpreter automatically compiles modules to bytecode on the first import and stores them in .pyc files. Compiling specific files is also possible. I am assuming this project is simply an exercise on the author's part. edit: precision

masklinn 11y ago
Well it might be possible for this one to implement a better bytecode optimiser and a better "stack flow", the standard interpreter only has a fairly simple peephole optimiser so it will e.g. store to locals to immediately reload the same local, or repeatedly load a name from the local or global scope rather than load it once and dup it: >>> @dis.dis ... def foo(): ... print a ... print a ... print a ... 3 0 LOAD_GLOBAL 0 (a) 3 PRINT_ITEM 4 PRINT_NEWLINE 4 5 LOAD_GLOBAL 0 (a) 8 PRINT_ITEM 9 PRINT_NEWLINE 5 10 LOAD_GLOBAL 0 (a) 13 PRINT_ITEM 14 PRINT_NEWLINE 15 LOAD_CONST 0 (None) 18 RETURN_VALUE I don't know how much value the optimised bytecode would bring though, likely not much outside of specific tight loops, and even then it's still only interpreted cpython, for little more cost you can integrate scipy solutions (e.g. numba) which'll likely have a much more significant impact.
- mborch 11y ago
  This is required due to Python's semantics. You can't optimize that away unless the code is written to explicitly turn a global into a local.
  - dalke 11y ago
    Here's an example of why mborch's statement is true: class A: def __init__(self, value=0): self.b = value def __str__(self): if self.b == 0: global a a = A(1) elif self.b == 1: import __builtin__, __main__ __builtin__.a = 2 del __main__.a return str(self.b) a = A() def foo(): print a print a print a foo() This generates: 1 2 3 but it's a different 'a' in all three cases; the last isn't even from the module's namespace.
    - stctgion 11y ago
      pretty sure that produces 0,1,2
      - dalke 11y ago
        Good catch! Yes, the output was from my first version. I rewrote it to be more explicit about changing the 'a' each time, and forgot to update the output section.

by trwired 11y ago

masklinn 11y ago

Well it might be possible for this one to implement a better bytecode optimiser and a better "stack flow", the standard interpreter only has a fairly simple peephole optimiser so it will e.g. store to locals to immediately reload the same local, or repeatedly load a name from the local or global scope rather than load it once and dup it: >>> @dis.dis ... def foo(): ... print a ... print a ... print a ... 3 0 LOAD_GLOBAL 0 (a) 3 PRINT_ITEM 4 PRINT_NEWLINE 4 5 LOAD_GLOBAL 0 (a) 8 PRINT_ITEM 9 PRINT_NEWLINE 5 10 LOAD_GLOBAL 0 (a) 13 PRINT_ITEM 14 PRINT_NEWLINE 15 LOAD_CONST 0 (None) 18 RETURN_VALUE I don't know how much value the optimised bytecode would bring though, likely not much outside of specific tight loops, and even then it's still only interpreted cpython, for little more cost you can integrate scipy solutions (e.g. numba) which'll likely have a much more significant impact.

mborch 11y ago
This is required due to Python's semantics. You can't optimize that away unless the code is written to explicitly turn a global into a local.
- dalke 11y ago
  Here's an example of why mborch's statement is true: class A: def __init__(self, value=0): self.b = value def __str__(self): if self.b == 0: global a a = A(1) elif self.b == 1: import __builtin__, __main__ __builtin__.a = 2 del __main__.a return str(self.b) a = A() def foo(): print a print a print a foo() This generates: 1 2 3 but it's a different 'a' in all three cases; the last isn't even from the module's namespace.
  - stctgion 11y ago
    pretty sure that produces 0,1,2
    - dalke 11y ago
      Good catch! Yes, the output was from my first version. I rewrote it to be more explicit about changing the 'a' each time, and forgot to update the output section.