Hello,
Is there any way to have fast dispatch based on the type of a variable?
I'm talking about code of the form:
t = type(var)
if t is int:
i(v)
elif t is long:
l(v)
elif t is float:
f(v)
elif t is str:
s(v)
elif t is unicode:
u(v)
...
I have tried these ideas:
- Having the types as keys in a dict and the functions as lambdas.
- Creating a list from min(type_hashes) to max(type_hashes) (with
lambdas as list values) and indexing in it with hash(var_type) -
min(type_hashes)
But both were slower than the multiple ifs.
The ideal case would be to have an optimization like C/C++ compilers do
to switch statements, where they would create a binary search over the
multiple cases like below:
Assuming that:
hash(int) < hash(long) < hash(float) ....
t=hash(type(var))
if t < hash(float):
if t < hash(long):
i(v)
else:
l(v)
else:
if t< hash(unicode):
s(v)
else:
u(v)
The problem in Python is that the order of type_hashes is not constant.
So it is not possible to create the binary search code.
Kind regards,
l.
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