[Python-Dev] Optimization of Python ASTs: How should we deal with constant values? (original) (raw)

"Martin v. Löwis" martin at v.loewis.de
Wed Apr 30 22:36:36 CEST 2008

This leaves us with a few options:

  1. Reuse/Abuse Num(object) for arbitrary constants. AFAICT, this should work out of the box.

1. A new AST expr node for constant values for types other than Str/Num

I imagine this to be something like Const(PyObject* v), which is effectively translated to a "LOADCONST v" by the compiler. This trades the purity of the AST for a little practicality. A "Const" node has no real source representation, it would exist solely for the purpose of injecting PyObject constants into the AST.

I think this is the way to go. It doesn't violate purity: it is an abstract syntax, meaning that there doesn't need to be a 1:1 relationship to source syntax. However, it is still possible to reproduce source code from this Const node.

I also don't worry about Jython conflicts. The grammar has a version number precisely so that you can refer to a specific version if you need to.

Regards, Martin

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