python file API

[Thomas Rachel]

Am 25.09.2012 00:37 schrieb Ian Kelly:
> On Mon, Sep 24, 2012 at 4:14 PM, Chris Angelico<rosuav at gmail.com>  wrote:
>> file.pos = 42 # Okay, you're at position 42
>> file.pos -= 10 # That should put you at position 32
>> foo = file.pos # Presumably foo is the integer 32
>> file.pos -= 100 # What should this do?
>
> Since ints are immutable, the language specifies that it should be the
> equivalent of "file.pos = file.pos - 100", so it should set the file
> pointer to 68 bytes before EOF.

But this is not a "real int", it has a special use. So I don't think it 
is absolutely required to behave like an int.

This reminds me of some special purpose registers in embedded 
programming, where bits can only be set by hardware and are cleared by 
the application by writing 1 to them.

Or some bit setting registers, like on ATxmega: OUT = 0x10 sets bit 7 
and clears all others, OUTSET = 0x10 only sets bit 7, OUTTGL = 0x10 
toggles it and OUTCLR = 0x10 clears it.

If this behaviour is documented properly enough, it is quite OK, IMHO.


Thomas