On Tue, Apr 19, 2016 at 2:13 AM, Xuancong Wang <xuancon...@gmail.com> wrote:
> Dear Cython developers,
>
> Python supports meta-programming, in which a variable with name
> specified in a string can be created at run-time. One built-in library
> which make use of this is argparse.
>
> For example:
>
> parser.add_argument('-N', '--max_threads', help='maximum number of
> concurrent decoding threads', type=int, default=16)
>
> in this case, the variable max_threads is created from the string
> argument. And then Cython will generate an incorrect C program with
> the following error:
>
> smt.py:78:88: undeclared name not builtin: headtail
> smt.c:1:2: error: #error Do not use this file, it is the result of a
> failed Cython compilation.
Argparse works just fine in Cython
import argparse
parser = argparse.ArgumentParser()
parser.add_argument('-N', '--max_threads', help='maximum number of
concurrent decoding threads', type=int, default=16)
args = parser.parse_args()
print args.max_threads
Could you provide a full example that you think should work? Where is
headtail defined? Is it another argument?
> In comparison, I found that nuitka can convert this kind of Python
> programs sucessfully. I hope Cython can be improved. Thanks!
>
argsparse dynamically adds the attributes to the returned object, which
works fine in Cython. Unless you're doing something like
http://stackoverflow.com/questions/19299635/python-argparse-parse-args-into-global-namespace-or-a-reason-this-is-a-bad-idea
That's one of the few places we diverge, because people strongly preferred
compile-time errors to runtime errors in this case.
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