[Python-Dev] Benchmarks why we need PEP 576/579/580 (original) (raw)

Jeroen Demeyer J.Demeyer at UGent.be
Mon Jul 23 08:16:00 EDT 2018

On 2018-07-23 00:28, Guido van Rossum wrote:

So does your implementation of the PEP result in a net increase or decrease of the total lines of code?

12 files changed, 918 insertions(+), 704 deletions(-)

That's a net increase, so there is no obvious win here. Still, I have various excuses for this increased number of lines of code:

  1. I'm adding more comments and lines containing only characters from the set " {};". This accounts for about 60% in the increase in number of lines of code. Clearly, this shouldn't count against me.

  2. I still need to support some old ways of doing things. For backwards compatibility, functions and methods are still defined using a PyMethodDef. So I need to convert this old structure to the new protocol. I also keep support for some functions that my PEP makes obsolete, such as PyCFunction_Call(). All this requires code, but that code is simple.

  3. In a few cases, specialized code is replaced by general code. For example, code that needs the name of a function changes from accessing a known field in a C structure (func->m_ml->ml_name) to an actual Python attribute lookup. And Python code like

def qualname(func): name = func.name try: parent_qualname = func.parent.qualname except AttributeError: return name return str(parent_qualname) + "." + name

is conceptually pretty simple, but it becomes 37 lines of C code in my implementation.

  1. The PEP does actually add a completely new feature: the flag CCALL_FUNCARG. That is something that I could easily remove for now, but PEP 580 would be a lot less useful without it. So it's something that I would certainly want to add in a later PEP anyway. It's also required for PEP 573.

Jeroen.

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