On Wednesday, September 20, 2017 at 10:31:04 PM UTC-7, Massimo Di Pierro wrote: > > In web2py, and in general in code that runs multithreaded you should not > define variables in modules at top level and then import them because they > are cached and then shared by multiple threads. That is not thread safe and > will cause all kind of problems. Modules should define functions and > classes, not objects. You should only import those functions and classes. > > I think it is a bit extreme to say that modules can only define functions and classes. Clearly they can also contain, for instance, "constant declarations" like "something = 2". My question is whether there is a way to define a query constraint as a "constant" in a similar way.
An expression like "db.MyTable.myfield > 2" does not conceptually need to know anything about the field, the table, or even the database at the time it is created. In this situation "query = db.MyTable.myfield > 2" would be no different from a constant assignment like "MY_CONSTANT = 7". There is no reason why the expression itself needs access to any thread state. It is only when the query is actually executed that it needs to be attached to a live database connection --- but that may be at a later time. What I'm asking is if there is a way to use the syntactic sugar of the DAL without any connection to an actual database, just to create a query expression that can be LATER attached to a database object. It appears the answer is no. Is that what you are saying? -- Resources: - http://web2py.com - http://web2py.com/book (Documentation) - http://github.com/web2py/web2py (Source code) - https://code.google.com/p/web2py/issues/list (Report Issues) --- You received this message because you are subscribed to the Google Groups "web2py-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to web2py+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
