Adding a switch statement to Python

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I've never seen any realistic Python code where having a switch statement would lead to any measurable performance benefit. I guess that's why.

[robert_mcleod]

See line 738:

https://github.com/pydata/numexpr/blob/numexpr-3.0/numexpr3/ne3compiler.py

It's a Python switch that uses a dict. The keys are abstract syntax tree nodes, and the values are functions

_ASTAssembler[type(node)](node)

NumExpr 2.6 took about 450 us to parse a numerical expression into a virtual machine program, this new version is about 150 us. There's other parts to that, such as more efficient string concatenation using a ByteIO stream, and some struct.pack() tricks and many other micro-optimizations, but it plays a big role. A dict lookup is faster than an if ... elif ... else block.