very small fix to _BinaryExpression.compare

[Former user]

Comparing two _BinaryExpressions have not considered that one of them could be reversed, i.e (Column, _BindParamClause) equals (_BindParamClause,Column) patch is simple.

I have found it looking at strange lazy load queries.

[Mike Bayer]

can you please describe something which you've seen fail without this patch ? some example code would be best.

[Mike Bayer]

not to mention that not all BinaryExpressions are commutative, awareness of this would need to be added.

[Former user]

Replying to zzzeek:

not to mention that not all BinaryExpressions are commutative, awareness of this would need to be added.

Heh! My fault. Of course, this patch should be used only for commutative operators, like '='.

[Former user]

I noticed that some simple lazy loads do not query database, if instance already in session, while others, very similar, still do.

The bug is that some lazy properties have use_get == False in LazyLoader.init because of uncorrect comparing of BinaryExpressions, where first BinaryExpression is

left: Column
operator: '='
right: _BindParamClause

and second is

left:_BindParamClause
operator: '='
right:Column

and Columns are the same.

It's seems evedent to me, that for commutative operators, comparing should be commutative too.

[Former user]

Fix now works only for '=' operator

[Mike Bayer]

OK i was looking for a test case here since those are generally needed for all checkins, but i managed to create one myself. fix is in changeset:2958, changeset:2959