As best I can tell, the anonymous blocks are used to take care of boilerplate code without changing the scope -- exactly what macros are used for. The only difference I see is that in this case, the macros are limited to entire (possibly compound) statements. To make this more concrete, Guido:
in synchronized(the_lock): BODY
Nick Coghlan:
s/in/with/ to get PEP 310. ...
Guido's recent screed crystallised the idea of writing resources as two-part generators: ...
[Adding Reinhold Birkenfeld's suggestion of a blank yield]
def my_resource(): print "Hi!" # Do entrance code yield # Go on with the contents of the 'with' block print "Bye!" # Do exit code
The macro itself looks reasonable -- so long as there is only ever one changing block inside the macro. I'm not sure that is a reasonable restriction, but the alternative is ugly enough that maybe passing around locals() starts to be just as good. What about a block that indicates the enclosed namespaces will collapse a level? defmacro myresource(filename): <make explicit calls to named callback "functions", but within the same locals() scope.> with myresource("thefile"): def reader(): ... def writer(): ... def fn(): .... Then myresource, reader, writer, and fn would share a namespace without having to manually pass it around. -jJ