Good news! You can have this right now in Perl:
$[ = 1;
$[ = 1;
The older I get the more Larry Wall strikes me as like a really well intentioned hippy type; when in God's green earth has it been a good idea to allow a five character statement change the truth values of nearly every for loop in a body of code?
Perl always claimed it gave you enough rope to hang yourself, but this goes far, far beyond that. This is like building the scaffolding and marking it like "Young developers, play here! Ropes are fun!"
How about this in C(and thousand others): #define if while
I am pretty sure I can find something to horrify you in almost any language.
#define break continue
irb(main):001:0> if 0
irb(main):002:1> print "True!"
irb(main):003:1> end
True!=> nil
>>> import sys
>>> import ctypes
>>> pyint_p = ctypes.POINTER(ctypes.c_byte*sys.getsizeof(5))
>>> five = ctypes.cast(id(5), pyint_p)
>>> 2 + 2 == 5
False
>>> five.contents[five.contents[:].index(5)] = 4
>>> 2 + 2 == 5
TrueHere's a small snippet that let you add methods to built-ins:
def inject(cls, wrapper=lambda x: x, name=None):
def _builtin_hack(name):
import ctypes as c
_get_dict = c.pythonapi._PyObject_GetDictPtr
_get_dict.restype = c.POINTER(c.py_object)
_get_dict.argtypes = [c.py_object]
return _get_dict(name).contents.value
def wrap(method):
name_ = name or method.func_name
method = wrapper(method)
try:
setattr(cls, name_, method)
except:
_builtin_hack(cls)[name_] = method
return wrap
@inject(dict)
def extend(self, new_dict):
return dict(self, **new_dict)
print {'a':2}.extend({'b':3})I think I discovered the hack when I found out about the id() function, and hex(id(5)) looked suspiciously like a pointer value. (And http://docs.python.org/library/functions.html#id confirms.) http://docs.python.org/library/ctypes.html has usually been pretty useful. Apart from that, just play.
$ python -c "import ctypes; ctypes.memset(0, 0, 42)"
Segmentation fault2) As of Perl 5+ it's evaluated at compile-time rather than run-time, which is not as bad as if you could flip back and forth at runtime. Though you can use 'local' to lexically scope its effects -- hilarity ensues as you hand off said code to someone else for maintenance.
3) It's from a different era. As per the docs:
Default is 0, but you could theoretically set
it to 1 to make Perl behave more like awk (or
Fortran)
[ Though the core of SciPy/NumPy is notably written in Fortran. Not quite as dead as some would have you believe. ]