RE strings (was: Variable Interpolation - status of PEP 215)

[Fredrik Lundh]

and while I'm at it:

> # match $$ and $var and ${var}
> _dosub = sre.compile(r'\$(?:\$|(\w+)|\{([^}]*)\})').sub

how about adding "re" strings (where the "e" tells Python
to run the string through the RE compiler):

    re"[-+]\d+"
    re"(\d+)\.(\d+)\.(\d+)\.(\d+)"
    _dosub = re'\$(?:\$|(\w+)|\{([^}]*)\})'.sub
    ishex = re'0[xX][\dA-Fa-f]'.match
    # etc

(or maybe a ".re" method that does the same thing, but
with an optional flag argument ?)

</F>