Array of functions, Pythonically

[MartinRinehart@gmail.com]

My parser has found an expression of the form CONSTANT_INTEGE R
OPERATOR CONSTANT_INTEGE R. I want to fold this into a single
CONSTANT_INTEGE R.

The OPERATOR token has an intValue attribute, '+' == 0, '-'== 1, etc.
In C I'd put functions Add, Subtract, ... into an array and call
ArithmeticFunct ions[ intValue ] to perform the operation. Would I
index into a list of functions in Python, or would IF/ELIF/ELIF ... be
the way to go?

[castironpi@gmail.com]

Re: Array of functions, Pythonically

 { '+': operator.add, '-': operator.sub, ... }

Then EXPR OPER EXPR -ops[ OPER ]( EXPR, EXPR ), right?

[Paul McGuire]

Re: Array of functions, Pythonically

On Feb 25, 11:53 am, castiro...@gmai l.com wrote:

 { '+': operator.add, '-': operator.sub, ... }

>
Then EXPR OPER EXPR -ops[ OPER ]( EXPR, EXPR ), right?

I think this is the most Pythonic idiom. You can even define your own
custom binary operators, such as '$' to convert dollars and cents to a
float:

>>ops = { '+': operator.add, '-': operator.sub, '$' : lambda a,b: a + b/100.0 }
>>ops['$'](1,2) # convert dollars and cents to float

1.02

-- Paul