I'm trying to use ClauseAdapter.traverse similar to how it's used in your 
old blog post to substitute columns in arbitrary clauses with columns on a 
different selectable that share an 
ancestor: http://techspot.zzzeek.org/archive/2008/01/1/

Even in a simple case using a BinaryExpression, 
ClauseAdapter(selectable).traverse(binaryexpression) is simply returning 
the expression.  When I looked at it with the debugger, it seems the 
expression isn't being traversed, but rather it eventually feeds the entire 
BinaryExpression object into corresponding_column and subsequently returns 
the full expression since obviously the BinaryExpression can't be matched 
to a particular column on the selectable.

selectable.corresponding_column(binaryexpression.left) returns the correct 
column, however ClauseAdapter(selectable).traverse(binaryexpression.left) 
does not.  The discrepancy is found in corresponding_column being called 
with require_embedded=True during traverse, which is hardcoded.  I don't 
know if this behavior causes the behavior I previously described with the 
BinaryExpression being passed to corresponding_column, but it seemed 
noteworthy.

Any ideas for fixes or alternatives?

Thanks



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